ImageLoader初始化以及调用

1、首先在当前程序的Application中调用ImageLoader的初始化init()方法

private void initImageLoader() {
        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(this).imageDownloader(
                new BaseImageDownloader(this, 60 * 1000, 60 * 1000)) // connectTimeout超时时间
                .build();
        ImageLoader.getInstance().init(config);
    }

2、下载图片的参数选项配置

 /**
  * 调用该方法下载图片
  * 配置imageLoader图片选项
  * @param iv  显示图片控件
  * @param url  网络或本地图片地址
  * @param defaultPic  默认图片
  * @param isRound  true为圆形，false不处理
  * @param cacheOnDisk true缓存到SD卡，false不缓存到SD卡
  */
public static void displayImages(ImageView iv,String url,int defaultPic,boolean isRound,boolean cacheOnDisk){
//配置一些图片选项
DisplayImageOptions options = new DisplayImageOptions.Builder()
.showImageOnLoading(defaultPic)// 设置图片在下载期间显示的图片
.showImageForEmptyUri(defaultPic)// 设置图片Uri为空或是错误的时候显示的图片
.showImageOnFail(defaultPic)// 设置图片加载/解码过程中错误时候显示的图片
.cacheInMemory(false)// 设置下载的图片是否缓存在内存中
.cacheOnDisk(cacheOnDisk)// 设置下载的图片是否缓存在SD卡中
.considerExifParams(true)//是否考虑JPEG图像EXIF参数（旋转，翻转）
.displayer(isRound ? new CircleBitmapDisplayer() : new SimpleBitmapDisplayer())//FadeInBitmapDisplayer(200)listview加载闪烁问题
.imageScaleType(ImageScaleType.IN_SAMPLE_POWER_OF_2)//图片将降低2倍，直到下一减少步骤，使图像更小的目标大小
.bitmapConfig(Bitmap.Config.RGB_565)//图片色彩565
.build();
imageLoader.displayImage(url, iv, options);

3、扩展，图片显示方式，圆角；CircleBitmapDisplayer()

private static class CircleBitmapDisplayer implements BitmapDisplayer {
            final int margin ;
            public CircleBitmapDisplayer() {
                this(0);
            }
            public CircleBitmapDisplayer(int margin) {
                this.margin = margin;
            }
            @Override
            public void display(Bitmap bitmap, ImageAware imageAware, LoadedFrom loadedFrom) {
                if (!(imageAware instanceof ImageViewAware)) {
                    throw new IllegalArgumentException("ImageAware should wrap ImageView. ImageViewAware is expected.");
                }
                imageAware.setImageBitmap(ToRoundBitmap.toRoundBitmap(bitmap));
            }
     }

4、返回圆形bitmap；toRoundBitmap()

public static  Bitmap toRoundBitmap(Bitmap bitmap) {
         int width = bitmap.getWidth();
         int height = bitmap.getHeight();
         float roundPx;
         float left,top,right,bottom,dst_left,dst_top,dst_right,dst_bottom;
         if (width <= height) {
              roundPx = width / 2;
              top = 0;
              left = 0;
              bottom = width;
              right = width;
              height = width;
              dst_left = 0;
              dst_top = 0;
              dst_right = width;
              dst_bottom = width;
          } else {
              roundPx = height / 2;
              float clip = (width - height) / 2;
              left = clip;
              right = width - clip;
              top = 0;
              bottom = height;
              width = height;
              dst_left = 0;
              dst_top = 0;
              dst_right = height;
              dst_bottom = height;
         }

            Bitmap output = Bitmap.createBitmap(width,height, Config.ARGB_8888);
            Canvas canvas = new Canvas(output);

            final int color = 0xff424242;
            final Paint paint = new Paint();
            final Rect src = new Rect((int)left, (int)top, (int)right, (int)bottom);
            final Rect dst = new Rect((int)dst_left, (int)dst_top, (int)dst_right, (int)dst_bottom);
            final RectF rectF = new RectF(dst);

            paint.setAntiAlias(true);

            canvas.drawARGB(0, 0, 0, 0);
            paint.setColor(Color.WHITE);

            paint.setStrokeWidth(4);
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
            paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
            canvas.drawBitmap(bitmap, src, dst, paint);

            return output ;
        }

5、根据图片uri返回bitmap；此缓存位置为内存

public static Bitmap getBitmapUtils(String imgUri){
        return imageLoader.getMemoryCache().get(imgUri);
    }

6、根据图片uri返回File；此缓存位置为sd卡

public static File getFileUtils(String imgUri){
        return imageLoader.getDiskCache().get(imgUri);
    }

7、获取imageloader缓存所有图片总计大小

public static long getCacheFileSize(){
        File disCacheFile = imageLoader.getDiskCache().getDirectory();
        long size = 0;
        for(int i=0; i<disCacheFile.listFiles().length; i++){
            size += disCacheFile.listFiles()[i].length();
        }
        return size;
    }

8、清除图片缓存

public static void clearImageCache(){
        imageLoader.clearDiskCache();//清除磁盘缓存
        imageLoader.clearMemoryCache();//清除内存缓存
    }

来源： http://blog.csdn.net/u010263943/article/details/52702455

来自为知笔记(Wiz)