Android-Universal-Image-Loader三大组件DisplayImageOptions、ImageLoader、ImageLoaderConfiguration详解

一、介绍

 Android-Universal-Image-Loader是一个开源的UI组件程序，该项目的目的是提供一个可重复使用的仪器为异步图像加载，缓存和显示。所以，如果你的程序里需要这个功能的话，那么不妨试试它。因为已经封装好了一些类和方法。我们 可以直接拿来用了。而不用重复去写了。其实，写一个这方面的程序还是比较麻烦的，要考虑多线程缓存，内存溢出等很多方面。

二、具体使用

一个好的类库的重要特征就是可配置性强。我们先简单使用Android-Universal-Image-Loader，一般情况下使用默认配置就可以了。

下面的实例利用Android-Universal-Image-Loader将网络图片加载到图片墙中。

public class BaseActivity extends Activity {
    ImageLoader imageLoader;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
          // Create global configuration and initialize ImageLoader with this configuration
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(getApplicationContext())
            .build();
        ImageLoader.getInstance().init(config);
        super.onCreate(savedInstanceState);
    }
}

public class MainActivity extends BaseActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
  
        ImageLoader imageLoader = ImageLoader.getInstance();

        GridView gridView = (GridView) this.findViewById(R.id.grdvImageWall);
        gridView.setAdapter(new PhotoWallAdapter(Constants.IMAGES));
    }

    static class ViewHolder {
        ImageView imageView;
        ProgressBar progressBar;
    }

    public class PhotoWallAdapter extends BaseAdapter {
        String[] imageUrls;
        ImageLoader imageLoad;
        DisplayImageOptions options;
        LinearLayout gridViewItem;

        public PhotoWallAdapter(String[] imageUrls) {
            assert imageUrls != null;
            this.imageUrls = imageUrls;

            options = new DisplayImageOptions.Builder()
                    .showImageOnLoading(R.drawable.ic_stub) // resource or
                                                            // drawable
                    .showImageForEmptyUri(R.drawable.ic_empty) // resource or
                                                                // drawable
                    .showImageOnFail(R.drawable.ic_error) // resource or
                                                            // drawable
                    .resetViewBeforeLoading(false) // default
                    .delayBeforeLoading(1000).cacheInMemory(false) // default
                    .cacheOnDisk(false) // default
                    .considerExifParams(false) // default
                    .imageScaleType(ImageScaleType.IN_SAMPLE_POWER_OF_2) // default
                    .bitmapConfig(Bitmap.Config.ARGB_8888) // default
                    .displayer(new SimpleBitmapDisplayer()) // default
                    .handler(new Handler()) // default
                    .build();
            this.imageLoad = ImageLoader.getInstance();

        }

        @Override
        public int getCount() {
            return this.imageUrls.length;
        }

        @Override
        public Object getItem(int position) {
            if (position <= 0 || position >= this.imageUrls.length) {
                throw new IllegalArgumentException(
                        "position<=0||position>=this.imageUrls.length");
            }
            return this.imageUrls[position];
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // 判断这个image是否已经在缓存当中，如果没有就下载
            final ViewHolder holder;
            if (convertView == null) {
                holder = new ViewHolder();
                gridViewItem = (LinearLayout) getLayoutInflater().inflate(
                        R.layout.image_wall_item, null);
                holder.imageView = (ImageView) gridViewItem
                        .findViewById(R.id.item_image);
                holder.progressBar = (ProgressBar) gridViewItem
                        .findViewById(R.id.item_process);
                gridViewItem.setTag(holder);
                convertView = gridViewItem;
            } else {
                holder = (ViewHolder) gridViewItem.getTag();
            }
            this.imageLoad.displayImage(this.imageUrls[position],
                    holder.imageView, options,
                    new SimpleImageLoadingListener() {

                        @Override
                        public void onLoadingStarted(String imageUri, View view) {
                            holder.progressBar.setProgress(0);
                            holder.progressBar.setVisibility(View.VISIBLE);
                        }

                        @Override
                        public void onLoadingFailed(String imageUri, View view,
                                FailReason failReason) {
                            holder.progressBar.setVisibility(View.GONE);
                        }

                        @Override
                        public void onLoadingComplete(String imageUri,
                                View view, Bitmap loadedImage) {
                            holder.progressBar.setVisibility(View.GONE);
                        }

                    }, new ImageLoadingProgressListener() {

                        @Override
                        public void onProgressUpdate(String imageUri,
                                View view, int current, int total) {
                            holder.progressBar.setProgress(Math.round(100.0f
                                    * current / total));
                        }
                    }); // 通过URL判断图片是否已经下载
            return convertView;
        }

    }
}

三者的关系

ImageLoaderConfiguration是针对图片缓存的全局配置，主要有线程类、缓存大小、磁盘大小、图片下载与解析、日志方面的配置。

ImageLoader是具体下载图片，缓存图片，显示图片的具体执行类，它有两个具体的方法displayImage(...)、loadImage(...)，但是其实最终他们的实现都是displayImage(...)。

DisplayImageOptions用于指导每一个Imageloader根据网络图片的状态（空白、下载错误、正在下载）显示对应的图片，是否将缓存加载到磁盘上，下载完后对图片进行怎么样的处理。

从三者的协作关系上看，他们有点像厨房规定、厨师、客户个人口味之间的关系。ImageLoaderConfiguration就像是厨房里面的规定，每一个厨师要怎么着装，要怎么保持厨房的干净，这是针对每一个厨师都适用的规定，而且不允许个性化改变。ImageLoader就像是具体做菜的厨师，负责具体菜谱的制作。DisplayImageOptions就像每个客户的偏好，根据客户是重口味还是清淡，每一个imageLoader根据DisplayImageOptions的要求具体执行。

ImageLoaderConfiguration

在上面的示例代码中，我们使用ImageLoaderConfiguration的默认配置，下面给出ImageLoaderConfiguration比较详尽的配置，从下面的配置中，可以看出ImageLoaderConfiguration的配置主要是全局性的配置，主要有线程类、缓存大小、磁盘大小、图片下载与解析、日志方面的配置。

ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(context)
        .memoryCacheExtraOptions(480, 800) // default = device screen dimensions
        .diskCacheExtraOptions(480, 800, null)
        .taskExecutor(...)
        .taskExecutorForCachedImages(...)
        .threadPoolSize(3) // default
        .threadPriority(Thread.NORM_PRIORITY - 1) // default
        .tasksProcessingOrder(QueueProcessingType.FIFO) // default
        .denyCacheImageMultipleSizesInMemory()
        .memoryCache(new LruMemoryCache(2 * 1024 * 1024))
        .memoryCacheSize(2 * 1024 * 1024)
        .memoryCacheSizePercentage(13) // default
        .diskCache(new UnlimitedDiscCache(cacheDir)) // default
        .diskCacheSize(50 * 1024 * 1024)
        .diskCacheFileCount(100)
        .diskCacheFileNameGenerator(new HashCodeFileNameGenerator()) // default
        .imageDownloader(new BaseImageDownloader(context)) // default
        .imageDecoder(new BaseImageDecoder()) // default
        .defaultDisplayImageOptions(DisplayImageOptions.createSimple()) // default
        .writeDebugLogs()
        .build();

ImageLoaderConfiguration的主要职责就是记录相关的配置，它的内部其实就是一些字段的集合（如下面的源代码）。它有一个builder的内部类，这个类中的字段跟ImageLoaderConfiguration中的字段完全一致，它有一些默认值，通过修改builder可以配置ImageLoaderConfiguration。

/*******************************************************************************
 * Copyright 2011-2013 Sergey Tarasevich
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *******************************************************************************/
package com.nostra13.universalimageloader.core;

import android.content.Context;
import android.content.res.Resources;
import android.util.DisplayMetrics;
import com.nostra13.universalimageloader.cache.disc.DiskCache;
import com.nostra13.universalimageloader.cache.disc.naming.FileNameGenerator;
import com.nostra13.universalimageloader.cache.memory.MemoryCache;
import com.nostra13.universalimageloader.cache.memory.impl.FuzzyKeyMemoryCache;
import com.nostra13.universalimageloader.core.assist.FlushedInputStream;
import com.nostra13.universalimageloader.core.assist.ImageSize;
import com.nostra13.universalimageloader.core.assist.QueueProcessingType;
import com.nostra13.universalimageloader.core.decode.ImageDecoder;
import com.nostra13.universalimageloader.core.download.ImageDownloader;
import com.nostra13.universalimageloader.core.process.BitmapProcessor;
import com.nostra13.universalimageloader.utils.L;
import com.nostra13.universalimageloader.utils.MemoryCacheUtils;

import java.io.IOException;
import java.io.InputStream;
import java.util.concurrent.Executor;

/**
 * Presents configuration for {@link ImageLoader}
 *
 * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
 * @see ImageLoader
 * @see MemoryCache
 * @see DiskCache
 * @see DisplayImageOptions
 * @see ImageDownloader
 * @see FileNameGenerator
 * @since 1.0.0
 */
public final class ImageLoaderConfiguration {

    final Resources resources;

    final int maxImageWidthForMemoryCache;
    final int maxImageHeightForMemoryCache;
    final int maxImageWidthForDiskCache;
    final int maxImageHeightForDiskCache;
    final BitmapProcessor processorForDiskCache;

    final Executor taskExecutor;
    final Executor taskExecutorForCachedImages;
    final boolean customExecutor;
    final boolean customExecutorForCachedImages;

    final int threadPoolSize;
    final int threadPriority;
    final QueueProcessingType tasksProcessingType;

    final MemoryCache memoryCache;
    final DiskCache diskCache;
    final ImageDownloader downloader;
    final ImageDecoder decoder;
    final DisplayImageOptions defaultDisplayImageOptions;

    final ImageDownloader networkDeniedDownloader;
    final ImageDownloader slowNetworkDownloader;

    private ImageLoaderConfiguration(final Builder builder) {
        resources = builder.context.getResources();
        maxImageWidthForMemoryCache = builder.maxImageWidthForMemoryCache;
        maxImageHeightForMemoryCache = builder.maxImageHeightForMemoryCache;
        maxImageWidthForDiskCache = builder.maxImageWidthForDiskCache;
        maxImageHeightForDiskCache = builder.maxImageHeightForDiskCache;
        processorForDiskCache = builder.processorForDiskCache;
        taskExecutor = builder.taskExecutor;
        taskExecutorForCachedImages = builder.taskExecutorForCachedImages;
        threadPoolSize = builder.threadPoolSize;
        threadPriority = builder.threadPriority;
        tasksProcessingType = builder.tasksProcessingType;
        diskCache = builder.diskCache;
        memoryCache = builder.memoryCache;
        defaultDisplayImageOptions = builder.defaultDisplayImageOptions;
        downloader = builder.downloader;
        decoder = builder.decoder;

        customExecutor = builder.customExecutor;
        customExecutorForCachedImages = builder.customExecutorForCachedImages;

        networkDeniedDownloader = new NetworkDeniedImageDownloader(downloader);
        slowNetworkDownloader = new SlowNetworkImageDownloader(downloader);

        L.writeDebugLogs(builder.writeLogs);
    }

    /**
     * Creates default configuration for {@link ImageLoader} <br />
     * <b>Default values:</b>
     * <ul>
     * <li>maxImageWidthForMemoryCache = device's screen width</li>
     * <li>maxImageHeightForMemoryCache = device's screen height</li>
     * <li>maxImageWidthForDikcCache = unlimited</li>
     * <li>maxImageHeightForDiskCache = unlimited</li>
     * <li>threadPoolSize = {@link Builder#DEFAULT_THREAD_POOL_SIZE this}</li>
     * <li>threadPriority = {@link Builder#DEFAULT_THREAD_PRIORITY this}</li>
     * <li>allow to cache different sizes of image in memory</li>
     * <li>memoryCache = {@link DefaultConfigurationFactory#createMemoryCache(int)}</li>
     * <li>diskCache = {@link com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiscCache}</li>
     * <li>imageDownloader = {@link DefaultConfigurationFactory#createImageDownloader(Context)}</li>
     * <li>imageDecoder = {@link DefaultConfigurationFactory#createImageDecoder(boolean)}</li>
     * <li>diskCacheFileNameGenerator = {@link DefaultConfigurationFactory#createFileNameGenerator()}</li>
     * <li>defaultDisplayImageOptions = {@link DisplayImageOptions#createSimple() Simple options}</li>
     * <li>tasksProcessingOrder = {@link QueueProcessingType#FIFO}</li>
     * <li>detailed logging disabled</li>
     * </ul>
     */
    public static ImageLoaderConfiguration createDefault(Context context) {
        return new Builder(context).build();
    }

    ImageSize getMaxImageSize() {
        DisplayMetrics displayMetrics = resources.getDisplayMetrics();

        int width = maxImageWidthForMemoryCache;
        if (width <= 0) {
            width = displayMetrics.widthPixels;
        }
        int height = maxImageHeightForMemoryCache;
        if (height <= 0) {
            height = displayMetrics.heightPixels;
        }
        return new ImageSize(width, height);
    }

    /**
     * Builder for {@link ImageLoaderConfiguration}
     *
     * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
     */
    public static class Builder {

        private static final String WARNING_OVERLAP_DISK_CACHE_PARAMS = "diskCache(), diskCacheSize() and diskCacheFileCount calls overlap each other";
        private static final String WARNING_OVERLAP_DISK_CACHE_NAME_GENERATOR = "diskCache() and diskCacheFileNameGenerator() calls overlap each other";
        private static final String WARNING_OVERLAP_MEMORY_CACHE = "memoryCache() and memoryCacheSize() calls overlap each other";
        private static final String WARNING_OVERLAP_EXECUTOR = "threadPoolSize(), threadPriority() and tasksProcessingOrder() calls "
                + "can overlap taskExecutor() and taskExecutorForCachedImages() calls.";

        /** {@value} */
        public static final int DEFAULT_THREAD_POOL_SIZE = 3;
        /** {@value} */
        public static final int DEFAULT_THREAD_PRIORITY = Thread.NORM_PRIORITY - 1;
        /** {@value} */
        public static final QueueProcessingType DEFAULT_TASK_PROCESSING_TYPE = QueueProcessingType.FIFO;

        private Context context;

        private int maxImageWidthForMemoryCache = 0;
        private int maxImageHeightForMemoryCache = 0;
        private int maxImageWidthForDiskCache = 0;
        private int maxImageHeightForDiskCache = 0;
        private BitmapProcessor processorForDiskCache = null;

        private Executor taskExecutor = null;
        private Executor taskExecutorForCachedImages = null;
        private boolean customExecutor = false;
        private boolean customExecutorForCachedImages = false;

        private int threadPoolSize = DEFAULT_THREAD_POOL_SIZE;
        private int threadPriority = DEFAULT_THREAD_PRIORITY;
        private boolean denyCacheImageMultipleSizesInMemory = false;
        private QueueProcessingType tasksProcessingType = DEFAULT_TASK_PROCESSING_TYPE;

        private int memoryCacheSize = 0;
        private long diskCacheSize = 0;
        private int diskCacheFileCount = 0;

        private MemoryCache memoryCache = null;
        private DiskCache diskCache = null;
        private FileNameGenerator diskCacheFileNameGenerator = null;
        private ImageDownloader downloader = null;
        private ImageDecoder decoder;
        private DisplayImageOptions defaultDisplayImageOptions = null;

        private boolean writeLogs = false;

        public Builder(Context context) {
            this.context = context.getApplicationContext();
        }

        /**
         * Sets options for memory cache
         *
         * @param maxImageWidthForMemoryCache  Maximum image width which will be used for memory saving during decoding
         *                                     an image to {@link android.graphics.Bitmap Bitmap}. <b>Default value - device's screen width</b>
         * @param maxImageHeightForMemoryCache Maximum image height which will be used for memory saving during decoding
         *                                     an image to {@link android.graphics.Bitmap Bitmap}. <b>Default value</b> - device's screen height
         */
        public Builder memoryCacheExtraOptions(int maxImageWidthForMemoryCache, int maxImageHeightForMemoryCache) {
            this.maxImageWidthForMemoryCache = maxImageWidthForMemoryCache;
            this.maxImageHeightForMemoryCache = maxImageHeightForMemoryCache;
            return this;
        }

        /**
         * @deprecated Use
         * {@link #diskCacheExtraOptions(int, int, com.nostra13.universalimageloader.core.process.BitmapProcessor)}
         * instead
         */
        @Deprecated
        public Builder discCacheExtraOptions(int maxImageWidthForDiskCache, int maxImageHeightForDiskCache,
                BitmapProcessor processorForDiskCache) {
            return diskCacheExtraOptions(maxImageWidthForDiskCache, maxImageHeightForDiskCache, processorForDiskCache);
        }

        /**
         * Sets options for resizing/compressing of downloaded images before saving to disk cache.<br />
         * <b>NOTE: Use this option only when you have appropriate needs. It can make ImageLoader slower.</b>
         *
         * @param maxImageWidthForDiskCache  Maximum width of downloaded images for saving at disk cache
         * @param maxImageHeightForDiskCache Maximum height of downloaded images for saving at disk cache
         * @param processorForDiskCache      null-ok; {@linkplain BitmapProcessor Bitmap processor} which process images before saving them in disc cache
         */
        public Builder diskCacheExtraOptions(int maxImageWidthForDiskCache, int maxImageHeightForDiskCache,
                BitmapProcessor processorForDiskCache) {
            this.maxImageWidthForDiskCache = maxImageWidthForDiskCache;
            this.maxImageHeightForDiskCache = maxImageHeightForDiskCache;
            this.processorForDiskCache = processorForDiskCache;
            return this;
        }

        /**
         * Sets custom {@linkplain Executor executor} for tasks of loading and displaying images.<br />
         * <br />
         * <b>NOTE:</b> If you set custom executor then following configuration options will not be considered for this
         * executor:
         * <ul>
         * <li>{@link #threadPoolSize(int)}</li>
         * <li>{@link #threadPriority(int)}</li>
         * <li>{@link #tasksProcessingOrder(QueueProcessingType)}</li>
         * </ul>
         *
         * @see #taskExecutorForCachedImages(Executor)
         */
        public Builder taskExecutor(Executor executor) {
            if (threadPoolSize != DEFAULT_THREAD_POOL_SIZE || threadPriority != DEFAULT_THREAD_PRIORITY || tasksProcessingType != DEFAULT_TASK_PROCESSING_TYPE) {
                L.w(WARNING_OVERLAP_EXECUTOR);
            }

            this.taskExecutor = executor;
            return this;
        }

        /**
         * Sets custom {@linkplain Executor executor} for tasks of displaying <b>cached on disk</b> images (these tasks
         * are executed quickly so UIL prefer to use separate executor for them).<br />
         * <br />
         * If you set the same executor for {@linkplain #taskExecutor(Executor) general tasks} and
         * tasks about cached images (this method) then these tasks will be in the
         * same thread pool. So short-lived tasks can wait a long time for their turn.<br />
         * <br />
         * <b>NOTE:</b> If you set custom executor then following configuration options will not be considered for this
         * executor:
         * <ul>
         * <li>{@link #threadPoolSize(int)}</li>
         * <li>{@link #threadPriority(int)}</li>
         * <li>{@link #tasksProcessingOrder(QueueProcessingType)}</li>
         * </ul>
         *
         * @see #taskExecutor(Executor)
         */
        public Builder taskExecutorForCachedImages(Executor executorForCachedImages) {
            if (threadPoolSize != DEFAULT_THREAD_POOL_SIZE || threadPriority != DEFAULT_THREAD_PRIORITY || tasksProcessingType != DEFAULT_TASK_PROCESSING_TYPE) {
                L.w(WARNING_OVERLAP_EXECUTOR);
            }

            this.taskExecutorForCachedImages = executorForCachedImages;
            return this;
        }

        /**
         * Sets thread pool size for image display tasks.<br />
         * Default value - {@link #DEFAULT_THREAD_POOL_SIZE this}
         */
        public Builder threadPoolSize(int threadPoolSize) {
            if (taskExecutor != null || taskExecutorForCachedImages != null) {
                L.w(WARNING_OVERLAP_EXECUTOR);
            }

            this.threadPoolSize = threadPoolSize;
            return this;
        }

        /**
         * Sets the priority for image loading threads. Should be <b>NOT</b> greater than {@link Thread#MAX_PRIORITY} or
         * less than {@link Thread#MIN_PRIORITY}<br />
         * Default value - {@link #DEFAULT_THREAD_PRIORITY this}
         */
        public Builder threadPriority(int threadPriority) {
            if (taskExecutor != null || taskExecutorForCachedImages != null) {
                L.w(WARNING_OVERLAP_EXECUTOR);
            }

            if (threadPriority < Thread.MIN_PRIORITY) {
                this.threadPriority = Thread.MIN_PRIORITY;
            } else {
                if (threadPriority > Thread.MAX_PRIORITY) {
                    this.threadPriority = Thread.MAX_PRIORITY;
                } else {
                    this.threadPriority = threadPriority;
                }
            }
            return this;
        }

        /**
         * When you display an image in a small {@link android.widget.ImageView ImageView} and later you try to display
         * this image (from identical URI) in a larger {@link android.widget.ImageView ImageView} so decoded image of
         * bigger size will be cached in memory as a previous decoded image of smaller size.<br />
         * So <b>the default behavior is to allow to cache multiple sizes of one image in memory</b>. You can
         * <b>deny</b> it by calling <b>this</b> method: so when some image will be cached in memory then previous
         * cached size of this image (if it exists) will be removed from memory cache before.
         */
        public Builder denyCacheImageMultipleSizesInMemory() {
            this.denyCacheImageMultipleSizesInMemory = true;
            return this;
        }

        /**
         * Sets type of queue processing for tasks for loading and displaying images.<br />
         * Default value - {@link QueueProcessingType#FIFO}
         */
        public Builder tasksProcessingOrder(QueueProcessingType tasksProcessingType) {
            if (taskExecutor != null || taskExecutorForCachedImages != null) {
                L.w(WARNING_OVERLAP_EXECUTOR);
            }

            this.tasksProcessingType = tasksProcessingType;
            return this;
        }

        /**
         * Sets maximum memory cache size for {@link android.graphics.Bitmap bitmaps} (in bytes).<br />
         * Default value - 1/8 of available app memory.<br />
         * <b>NOTE:</b> If you use this method then
         * {@link com.nostra13.universalimageloader.cache.memory.impl.LruMemoryCache LruMemoryCache} will be used as
         * memory cache. You can use {@link #memoryCache(MemoryCache)} method to set your own implementation of
         * {@link MemoryCache}.
         */
        public Builder memoryCacheSize(int memoryCacheSize) {
            if (memoryCacheSize <= 0) throw new IllegalArgumentException("memoryCacheSize must be a positive number");

            if (memoryCache != null) {
                L.w(WARNING_OVERLAP_MEMORY_CACHE);
            }

            this.memoryCacheSize = memoryCacheSize;
            return this;
        }

        /**
         * Sets maximum memory cache size (in percent of available app memory) for {@link android.graphics.Bitmap
         * bitmaps}.<br />
         * Default value - 1/8 of available app memory.<br />
         * <b>NOTE:</b> If you use this method then
         * {@link com.nostra13.universalimageloader.cache.memory.impl.LruMemoryCache LruMemoryCache} will be used as
         * memory cache. You can use {@link #memoryCache(MemoryCache)} method to set your own implementation of
         * {@link MemoryCache}.
         */
        public Builder memoryCacheSizePercentage(int availableMemoryPercent) {
            if (availableMemoryPercent <= 0 || availableMemoryPercent >= 100) {
                throw new IllegalArgumentException("availableMemoryPercent must be in range (0 < % < 100)");
            }

            if (memoryCache != null) {
                L.w(WARNING_OVERLAP_MEMORY_CACHE);
            }

            long availableMemory = Runtime.getRuntime().maxMemory();
            memoryCacheSize = (int) (availableMemory * (availableMemoryPercent / 100f));
            return this;
        }

        /**
         * Sets memory cache for {@link android.graphics.Bitmap bitmaps}.<br />
         * Default value - {@link com.nostra13.universalimageloader.cache.memory.impl.LruMemoryCache LruMemoryCache}
         * with limited memory cache size (size = 1/8 of available app memory)<br />
         * <br />
         * <b>NOTE:</b> If you set custom memory cache then following configuration option will not be considered:
         * <ul>
         * <li>{@link #memoryCacheSize(int)}</li>
         * </ul>
         */
        public Builder memoryCache(MemoryCache memoryCache) {
            if (memoryCacheSize != 0) {
                L.w(WARNING_OVERLAP_MEMORY_CACHE);
            }

            this.memoryCache = memoryCache;
            return this;
        }

        /** @deprecated Use {@link #diskCacheSize(int)} instead */
        @Deprecated
        public Builder discCacheSize(int maxCacheSize) {
            return diskCacheSize(maxCacheSize);
        }

        /**
         * Sets maximum disk cache size for images (in bytes).<br />
         * By default: disk cache is unlimited.<br />
         * <b>NOTE:</b> If you use this method then
         * {@link com.nostra13.universalimageloader.cache.disc.impl.ext.LruDiscCache LruDiscCache}
         * will be used as disk cache. You can use {@link #diskCache(DiskCache)} method for introduction your own
         * implementation of {@link DiskCache}
         */
        public Builder diskCacheSize(int maxCacheSize) {
            if (maxCacheSize <= 0) throw new IllegalArgumentException("maxCacheSize must be a positive number");

            if (diskCache != null) {
                L.w(WARNING_OVERLAP_DISK_CACHE_PARAMS);
            }

            this.diskCacheSize = maxCacheSize;
            return this;
        }

        /** @deprecated Use {@link #diskCacheFileCount(int)} instead */
        @Deprecated
        public Builder discCacheFileCount(int maxFileCount) {
            return diskCacheFileCount(maxFileCount);
        }

        /**
         * Sets maximum file count in disk cache directory.<br />
         * By default: disk cache is unlimited.<br />
         * <b>NOTE:</b> If you use this method then
         * {@link com.nostra13.universalimageloader.cache.disc.impl.ext.LruDiscCache LruDiscCache}
         * will be used as disk cache. You can use {@link #diskCache(DiskCache)} method for introduction your own
         * implementation of {@link DiskCache}
         */
        public Builder diskCacheFileCount(int maxFileCount) {
            if (maxFileCount <= 0) throw new IllegalArgumentException("maxFileCount must be a positive number");

            if (diskCache != null) {
                L.w(WARNING_OVERLAP_DISK_CACHE_PARAMS);
            }

            this.diskCacheFileCount = maxFileCount;
            return this;
        }

        /** @deprecated Use {@link #diskCacheFileNameGenerator(com.nostra13.universalimageloader.cache.disc.naming.FileNameGenerator)} */
        @Deprecated
        public Builder discCacheFileNameGenerator(FileNameGenerator fileNameGenerator) {
            return diskCacheFileNameGenerator(fileNameGenerator);
        }

        /**
         * Sets name generator for files cached in disk cache.<br />
         * Default value -
         * {@link com.nostra13.universalimageloader.core.DefaultConfigurationFactory#createFileNameGenerator()
         * DefaultConfigurationFactory.createFileNameGenerator()}
         */
        public Builder diskCacheFileNameGenerator(FileNameGenerator fileNameGenerator) {
            if (diskCache != null) {
                L.w(WARNING_OVERLAP_DISK_CACHE_NAME_GENERATOR);
            }

            this.diskCacheFileNameGenerator = fileNameGenerator;
            return this;
        }

        /** @deprecated Use {@link #diskCache(com.nostra13.universalimageloader.cache.disc.DiskCache)} */
        @Deprecated
        public Builder discCache(DiskCache diskCache) {
            return diskCache(diskCache);
        }

        /**
         * Sets disk cache for images.<br />
         * Default value - {@link com.nostra13.universalimageloader.cache.disc.impl.UnlimitedDiscCache
         * BaseDiscCache}. Cache directory is defined by
         * {@link com.nostra13.universalimageloader.utils.StorageUtils#getCacheDirectory(Context)
         * StorageUtils.getCacheDirectory(Context)}.<br />
         * <br />
         * <b>NOTE:</b> If you set custom disk cache then following configuration option will not be considered:
         * <ul>
         * <li>{@link #diskCacheSize(int)}</li>
         * <li>{@link #diskCacheFileCount(int)}</li>
         * <li>{@link #diskCacheFileNameGenerator(FileNameGenerator)}</li>
         * </ul>
         */
        public Builder diskCache(DiskCache diskCache) {
            if (diskCacheSize > 0 || diskCacheFileCount > 0) {
                L.w(WARNING_OVERLAP_DISK_CACHE_PARAMS);
            }
            if (diskCacheFileNameGenerator != null) {
                L.w(WARNING_OVERLAP_DISK_CACHE_NAME_GENERATOR);
            }

            this.diskCache = diskCache;
            return this;
        }

        /**
         * Sets utility which will be responsible for downloading of image.<br />
         * Default value -
         * {@link com.nostra13.universalimageloader.core.DefaultConfigurationFactory#createImageDownloader(Context)
         * DefaultConfigurationFactory.createImageDownloader()}
         */
        public Builder imageDownloader(ImageDownloader imageDownloader) {
            this.downloader = imageDownloader;
            return this;
        }

        /**
         * Sets utility which will be responsible for decoding of image stream.<br />
         * Default value -
         * {@link com.nostra13.universalimageloader.core.DefaultConfigurationFactory#createImageDecoder(boolean)
         * DefaultConfigurationFactory.createImageDecoder()}
         */
        public Builder imageDecoder(ImageDecoder imageDecoder) {
            this.decoder = imageDecoder;
            return this;
        }

        /**
         * Sets default {@linkplain DisplayImageOptions display image options} for image displaying. These options will
         * be used for every {@linkplain ImageLoader#displayImage(String, android.widget.ImageView) image display call}
         * without passing custom {@linkplain DisplayImageOptions options}<br />
         * Default value - {@link DisplayImageOptions#createSimple() Simple options}
         */
        public Builder defaultDisplayImageOptions(DisplayImageOptions defaultDisplayImageOptions) {
            this.defaultDisplayImageOptions = defaultDisplayImageOptions;
            return this;
        }

        /**
         * Enables detail logging of {@link ImageLoader} work. To prevent detail logs don't call this method.
         * Consider {@link com.nostra13.universalimageloader.utils.L#disableLogging()} to disable
         * ImageLoader logging completely (even error logs)
         */
        public Builder writeDebugLogs() {
            this.writeLogs = true;
            return this;
        }

        /** Builds configured {@link ImageLoaderConfiguration} object */
        public ImageLoaderConfiguration build() {
            initEmptyFieldsWithDefaultValues();
            return new ImageLoaderConfiguration(this);
        }

        private void initEmptyFieldsWithDefaultValues() {
            if (taskExecutor == null) {
                taskExecutor = DefaultConfigurationFactory
                        .createExecutor(threadPoolSize, threadPriority, tasksProcessingType);
            } else {
                customExecutor = true;
            }
            if (taskExecutorForCachedImages == null) {
                taskExecutorForCachedImages = DefaultConfigurationFactory
                        .createExecutor(threadPoolSize, threadPriority, tasksProcessingType);
            } else {
                customExecutorForCachedImages = true;
            }
            if (diskCache == null) {
                if (diskCacheFileNameGenerator == null) {
                    diskCacheFileNameGenerator = DefaultConfigurationFactory.createFileNameGenerator();
                }
                diskCache = DefaultConfigurationFactory
                        .createDiskCache(context, diskCacheFileNameGenerator, diskCacheSize, diskCacheFileCount);
            }
            if (memoryCache == null) {
                memoryCache = DefaultConfigurationFactory.createMemoryCache(memoryCacheSize);
            }
            if (denyCacheImageMultipleSizesInMemory) {
                memoryCache = new FuzzyKeyMemoryCache(memoryCache, MemoryCacheUtils.createFuzzyKeyComparator());
            }
            if (downloader == null) {
                downloader = DefaultConfigurationFactory.createImageDownloader(context);
            }
            if (decoder == null) {
                decoder = DefaultConfigurationFactory.createImageDecoder(writeLogs);
            }
            if (defaultDisplayImageOptions == null) {
                defaultDisplayImageOptions = DisplayImageOptions.createSimple();
            }
        }
    }

    /**
     * Decorator. Prevents downloads from network (throws {@link IllegalStateException exception}).<br />
     * In most cases this downloader shouldn't be used directly.
     *
     * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
     * @since 1.8.0
     */
    private static class NetworkDeniedImageDownloader implements ImageDownloader {

        private final ImageDownloader wrappedDownloader;

        public NetworkDeniedImageDownloader(ImageDownloader wrappedDownloader) {
            this.wrappedDownloader = wrappedDownloader;
        }

        @Override
        public InputStream getStream(String imageUri, Object extra) throws IOException {
            switch (Scheme.ofUri(imageUri)) {
                case HTTP:
                case HTTPS:
                    throw new IllegalStateException();
                default:
                    return wrappedDownloader.getStream(imageUri, extra);
            }
        }
    }

    /**
     * Decorator. Handles <a href="http://code.google.com/p/android/issues/detail?id=6066">this problem</a> on slow networks
     * using {@link com.nostra13.universalimageloader.core.assist.FlushedInputStream}.
     *
     * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
     * @since 1.8.1
     */
    private static class SlowNetworkImageDownloader implements ImageDownloader {

        private final ImageDownloader wrappedDownloader;

        public SlowNetworkImageDownloader(ImageDownloader wrappedDownloader) {
            this.wrappedDownloader = wrappedDownloader;
        }

        @Override
        public InputStream getStream(String imageUri, Object extra) throws IOException {
            InputStream imageStream = wrappedDownloader.getStream(imageUri, extra);
            switch (Scheme.ofUri(imageUri)) {
                case HTTP:
                case HTTPS:
                    return new FlushedInputStream(imageStream);
                default:
                    return imageStream;
            }
        }
    }
}

 Display Options

每一个ImageLoader.displayImage(...)都可以使用Display Options。

DisplayImageOptions options = new DisplayImageOptions.Builder()
        .showImageOnLoading(R.drawable.ic_stub) // resource or drawable
        .showImageForEmptyUri(R.drawable.ic_empty) // resource or drawable
        .showImageOnFail(R.drawable.ic_error) // resource or drawable
        .resetViewBeforeLoading(false)  // default
        .delayBeforeLoading(1000)
        .cacheInMemory(false) // default
        .cacheOnDisk(false) // default
        .preProcessor(...)
        .postProcessor(...)
        .extraForDownloader(...)
        .considerExifParams(false) // default
        .imageScaleType(ImageScaleType.IN_SAMPLE_POWER_OF_2) // default
        .bitmapConfig(Bitmap.Config.ARGB_8888) // default
        .decodingOptions(...)
        .displayer(new SimpleBitmapDisplayer()) // default
        .handler(new Handler()) // default
        .build();

 Display Options的主要职责就是记录相关的配置，它的内部其实就是一些字段的集合（如下面的源代码）。它有一个builder的内部类，这个类中的字段跟DisplayOption中的字段完全一致，它有一些默认值，通过修改builder可以配置DisplayOptions。

public final class DisplayImageOptions {

    private final int imageResOnLoading;
    private final int imageResForEmptyUri;
    private final int imageResOnFail;
    private final Drawable imageOnLoading;
    private final Drawable imageForEmptyUri;
    private final Drawable imageOnFail;
    private final boolean resetViewBeforeLoading;
    private final boolean cacheInMemory;
    private final boolean cacheOnDisk;
    private final ImageScaleType imageScaleType;
    private final Options decodingOptions;
    private final int delayBeforeLoading;
    private final boolean considerExifParams;
    private final Object extraForDownloader;
    private final BitmapProcessor preProcessor;
    private final BitmapProcessor postProcessor;
    private final BitmapDisplayer displayer;
    private final Handler handler;
    private final boolean isSyncLoading;

    private DisplayImageOptions(Builder builder) {
        imageResOnLoading = builder.imageResOnLoading;
        imageResForEmptyUri = builder.imageResForEmptyUri;
        imageResOnFail = builder.imageResOnFail;
        imageOnLoading = builder.imageOnLoading;
        imageForEmptyUri = builder.imageForEmptyUri;
        imageOnFail = builder.imageOnFail;
        resetViewBeforeLoading = builder.resetViewBeforeLoading;
        cacheInMemory = builder.cacheInMemory;
        cacheOnDisk = builder.cacheOnDisk;
        imageScaleType = builder.imageScaleType;
        decodingOptions = builder.decodingOptions;
        delayBeforeLoading = builder.delayBeforeLoading;
        considerExifParams = builder.considerExifParams;
        extraForDownloader = builder.extraForDownloader;
        preProcessor = builder.preProcessor;
        postProcessor = builder.postProcessor;
        displayer = builder.displayer;
        handler = builder.handler;
        isSyncLoading = builder.isSyncLoading;
    }

    public boolean shouldShowImageOnLoading() {
        return imageOnLoading != null || imageResOnLoading != 0;
    }

    public boolean shouldShowImageForEmptyUri() {
        return imageForEmptyUri != null || imageResForEmptyUri != 0;
    }

    public boolean shouldShowImageOnFail() {
        return imageOnFail != null || imageResOnFail != 0;
    }

    public boolean shouldPreProcess() {
        return preProcessor != null;
    }

    public boolean shouldPostProcess() {
        return postProcessor != null;
    }

    public boolean shouldDelayBeforeLoading() {
        return delayBeforeLoading > 0;
    }

    public Drawable getImageOnLoading(Resources res) {
        return imageResOnLoading != 0 ? res.getDrawable(imageResOnLoading) : imageOnLoading;
    }

    public Drawable getImageForEmptyUri(Resources res) {
        return imageResForEmptyUri != 0 ? res.getDrawable(imageResForEmptyUri) : imageForEmptyUri;
    }

    public Drawable getImageOnFail(Resources res) {
        return imageResOnFail != 0 ? res.getDrawable(imageResOnFail) : imageOnFail;
    }

    public boolean isResetViewBeforeLoading() {
        return resetViewBeforeLoading;
    }

    public boolean isCacheInMemory() {
        return cacheInMemory;
    }

    public boolean isCacheOnDisk() {
        return cacheOnDisk;
    }

    public ImageScaleType getImageScaleType() {
        return imageScaleType;
    }

    public Options getDecodingOptions() {
        return decodingOptions;
    }

    public int getDelayBeforeLoading() {
        return delayBeforeLoading;
    }

    public boolean isConsiderExifParams() {
        return considerExifParams;
    }

    public Object getExtraForDownloader() {
        return extraForDownloader;
    }

    public BitmapProcessor getPreProcessor() {
        return preProcessor;
    }

    public BitmapProcessor getPostProcessor() {
        return postProcessor;
    }

    public BitmapDisplayer getDisplayer() {
        return displayer;
    }

    public Handler getHandler() {
        return handler;
    }

    boolean isSyncLoading() {
        return isSyncLoading;
    }

    /**
     * Builder for {@link DisplayImageOptions}
     *
     * @author Sergey Tarasevich (nostra13[at]gmail[dot]com)
     */
    public static class Builder {
        private int imageResOnLoading = 0;
        private int imageResForEmptyUri = 0;
        private int imageResOnFail = 0;
        private Drawable imageOnLoading = null;
        private Drawable imageForEmptyUri = null;
        private Drawable imageOnFail = null;
        private boolean resetViewBeforeLoading = false;
        private boolean cacheInMemory = false;
        private boolean cacheOnDisk = false;
        private ImageScaleType imageScaleType = ImageScaleType.IN_SAMPLE_POWER_OF_2;
        private Options decodingOptions = new Options();
        private int delayBeforeLoading = 0;
        private boolean considerExifParams = false;
        private Object extraForDownloader = null;
        private BitmapProcessor preProcessor = null;
        private BitmapProcessor postProcessor = null;
        private BitmapDisplayer displayer = DefaultConfigurationFactory.createBitmapDisplayer();
        private Handler handler = null;
        private boolean isSyncLoading = false;

        public Builder() {
            decodingOptions.inPurgeable = true;
            decodingOptions.inInputShareable = true;
        }

        /**
         * Stub image will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} during image loading
         *
         * @param imageRes Stub image resource
         * @deprecated Use {@link #showImageOnLoading(int)} instead
         */
        @Deprecated
        public Builder showStubImage(int imageRes) {
            imageResOnLoading = imageRes;
            return this;
        }

        /**
         * Incoming image will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} during image loading
         *
         * @param imageRes Image resource
         */
        public Builder showImageOnLoading(int imageRes) {
            imageResOnLoading = imageRes;
            return this;
        }

        /**
         * Incoming drawable will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} during image loading.
         * This option will be ignored if {@link DisplayImageOptions.Builder#showImageOnLoading(int)} is set.
         */
        public Builder showImageOnLoading(Drawable drawable) {
            imageOnLoading = drawable;
            return this;
        }

        /**
         * Incoming image will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} if empty URI (null or empty
         * string) will be passed to <b>ImageLoader.displayImage(...)</b> method.
         *
         * @param imageRes Image resource
         */
        public Builder showImageForEmptyUri(int imageRes) {
            imageResForEmptyUri = imageRes;
            return this;
        }

        /**
         * Incoming drawable will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} if empty URI (null or empty
         * string) will be passed to <b>ImageLoader.displayImage(...)</b> method.
         * This option will be ignored if {@link DisplayImageOptions.Builder#showImageForEmptyUri(int)} is set.
         */
        public Builder showImageForEmptyUri(Drawable drawable) {
            imageForEmptyUri = drawable;
            return this;
        }

        /**
         * Incoming image will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} if some error occurs during
         * requested image loading/decoding.
         *
         * @param imageRes Image resource
         */
        public Builder showImageOnFail(int imageRes) {
            imageResOnFail = imageRes;
            return this;
        }

        /**
         * Incoming drawable will be displayed in {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} if some error occurs during
         * requested image loading/decoding.
         * This option will be ignored if {@link DisplayImageOptions.Builder#showImageOnFail(int)} is set.
         */
        public Builder showImageOnFail(Drawable drawable) {
            imageOnFail = drawable;
            return this;
        }

        /**
         * {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} will be reset (set <b>null</b>) before image loading start
         *
         * @deprecated Use {@link #resetViewBeforeLoading(boolean) resetViewBeforeLoading(true)} instead
         */
        public Builder resetViewBeforeLoading() {
            resetViewBeforeLoading = true;
            return this;
        }

        /**
         * Sets whether {@link com.nostra13.universalimageloader.core.imageaware.ImageAware
         * image aware view} will be reset (set <b>null</b>) before image loading start
         */
        public Builder resetViewBeforeLoading(boolean resetViewBeforeLoading) {
            this.resetViewBeforeLoading = resetViewBeforeLoading;
            return this;
        }

        /**
         * Loaded image will be cached in memory
         *
         * @deprecated Use {@link #cacheInMemory(boolean) cacheInMemory(true)} instead
         */
        @Deprecated
        public Builder cacheInMemory() {
            cacheInMemory = true;
            return this;
        }

        /** Sets whether loaded image will be cached in memory */
        public Builder cacheInMemory(boolean cacheInMemory) {
            this.cacheInMemory = cacheInMemory;
            return this;
        }

        /**
         * Loaded image will be cached on disk
         *
         * @deprecated Use {@link #cacheOnDisk(boolean) cacheOnDisk(true)} instead
         */
        @Deprecated
        public Builder cacheOnDisc() {
            return cacheOnDisk(true);
        }

        /**
         * Sets whether loaded image will be cached on disk
         *
         * @deprecated Use {@link #cacheOnDisk(boolean)} instead
         */
        @Deprecated
        public Builder cacheOnDisc(boolean cacheOnDisk) {
            return cacheOnDisk(cacheOnDisk);
        }

        /** Sets whether loaded image will be cached on disk */
        public Builder cacheOnDisk(boolean cacheOnDisk) {
            this.cacheOnDisk = cacheOnDisk;
            return this;
        }

        /**
         * Sets {@linkplain ImageScaleType scale type} for decoding image. This parameter is used while define scale
         * size for decoding image to Bitmap. Default value - {@link ImageScaleType#IN_SAMPLE_POWER_OF_2}
         */
        public Builder imageScaleType(ImageScaleType imageScaleType) {
            this.imageScaleType = imageScaleType;
            return this;
        }

        /** Sets {@link Bitmap.Config bitmap config} for image decoding. Default value - {@link Bitmap.Config#ARGB_8888} */
        public Builder bitmapConfig(Bitmap.Config bitmapConfig) {
            if (bitmapConfig == null) throw new IllegalArgumentException("bitmapConfig can't be null");
            decodingOptions.inPreferredConfig = bitmapConfig;
            return this;
        }

        /**
         * Sets options for image decoding.<br />
         * <b>NOTE:</b> {@link Options#inSampleSize} of incoming options will <b>NOT</b> be considered. Library
         * calculate the most appropriate sample size itself according yo {@link #imageScaleType(ImageScaleType)}
         * options.<br />
         * <b>NOTE:</b> This option overlaps {@link #bitmapConfig(android.graphics.Bitmap.Config) bitmapConfig()}
         * option.
         */
        public Builder decodingOptions(Options decodingOptions) {
            if (decodingOptions == null) throw new IllegalArgumentException("decodingOptions can't be null");
            this.decodingOptions = decodingOptions;
            return this;
        }

        /** Sets delay time before starting loading task. Default - no delay. */
        public Builder delayBeforeLoading(int delayInMillis) {
            this.delayBeforeLoading = delayInMillis;
            return this;
        }

        /** Sets auxiliary object which will be passed to {@link ImageDownloader#getStream(String, Object)} */
        public Builder extraForDownloader(Object extra) {
            this.extraForDownloader = extra;
            return this;
        }

        /** Sets whether ImageLoader will consider EXIF parameters of JPEG image (rotate, flip) */
        public Builder considerExifParams(boolean considerExifParams) {
            this.considerExifParams = considerExifParams;
            return this;
        }

        /**
         * Sets bitmap processor which will be process bitmaps before they will be cached in memory. So memory cache
         * will contain bitmap processed by incoming preProcessor.<br />
         * Image will be pre-processed even if caching in memory is disabled.
         */
        public Builder preProcessor(BitmapProcessor preProcessor) {
            this.preProcessor = preProcessor;
            return this;
        }

        /**
         * Sets bitmap processor which will be process bitmaps before they will be displayed in
         * {@link com.nostra13.universalimageloader.core.imageaware.ImageAware image aware view} but
         * after they'll have been saved in memory cache.
         */
        public Builder postProcessor(BitmapProcessor postProcessor) {
            this.postProcessor = postProcessor;
            return this;
        }

        /**
         * Sets custom {@link BitmapDisplayer displayer} for image loading task. Default value -
         * {@link DefaultConfigurationFactory#createBitmapDisplayer()}
         */
        public Builder displayer(BitmapDisplayer displayer) {
            if (displayer == null) throw new IllegalArgumentException("displayer can't be null");
            this.displayer = displayer;
            return this;
        }

        Builder syncLoading(boolean isSyncLoading) {
            this.isSyncLoading = isSyncLoading;
            return this;
        }

        /**
         * Sets custom {@linkplain Handler handler} for displaying images and firing {@linkplain ImageLoadingListener
         * listener} events.
         */
        public Builder handler(Handler handler) {
            this.handler = handler;
            return this;
        }

        /** Sets all options equal to incoming options */
        public Builder cloneFrom(DisplayImageOptions options) {
            imageResOnLoading = options.imageResOnLoading;
            imageResForEmptyUri = options.imageResForEmptyUri;
            imageResOnFail = options.imageResOnFail;
            imageOnLoading = options.imageOnLoading;
            imageForEmptyUri = options.imageForEmptyUri;
            imageOnFail = options.imageOnFail;
            resetViewBeforeLoading = options.resetViewBeforeLoading;
            cacheInMemory = options.cacheInMemory;
            cacheOnDisk = options.cacheOnDisk;
            imageScaleType = options.imageScaleType;
            decodingOptions = options.decodingOptions;
            delayBeforeLoading = options.delayBeforeLoading;
            considerExifParams = options.considerExifParams;
            extraForDownloader = options.extraForDownloader;
            preProcessor = options.preProcessor;
            postProcessor = options.postProcessor;
            displayer = options.displayer;
            handler = options.handler;
            isSyncLoading = options.isSyncLoading;
            return this;
        }

        /** Builds configured {@link DisplayImageOptions} object */
        public DisplayImageOptions build() {
            return new DisplayImageOptions(this);
        }
    }

    /**
     * Creates options appropriate for single displaying:
     * <ul>
     * <li>View will <b>not</b> be reset before loading</li>
     * <li>Loaded image will <b>not</b> be cached in memory</li>
     * <li>Loaded image will <b>not</b> be cached on disk</li>
     * <li>{@link ImageScaleType#IN_SAMPLE_POWER_OF_2} decoding type will be used</li>
     * <li>{@link Bitmap.Config#ARGB_8888} bitmap config will be used for image decoding</li>
     * <li>{@link SimpleBitmapDisplayer} will be used for image displaying</li>
     * </ul>
     * <p/>
     * These option are appropriate for simple single-use image (from drawables or from Internet) displaying.
     */
    public static DisplayImageOptions createSimple() {
        return new Builder().build();
    }
}

参考链接

http://blog.csdn.net/wangjinyu501/article/details/8091623

https://github.com/nostra13/Android-Universal-Image-Loader

http://www.intexsoft.com/blog/item/74-universal-image-loader-part-3.html