[转载]Android开发之读取文件夹下图片生成略缩图并点击显示大图

这是一个简单的Demo，目的是：读取文件夹下图片生成略缩图并点击显示大图。

先新建一个工程，创建一个ThumbnailsWindows的类，继承LinearLayout。代码如下：

package org.winplus.thum.view;  

import java.io.File;  
import java.io.FileInputStream;  
import java.io.FileNotFoundException;  
import java.io.InputStream;  
import java.util.ArrayList;  
import java.util.Collections;  
import java.util.Iterator;  
import java.util.Map;  
import java.util.TreeMap;  

import android.content.Context;  
import android.graphics.Bitmap;  
import android.graphics.BitmapFactory;  
import android.util.AttributeSet;  
import android.view.LayoutInflater;  
import android.view.MotionEvent;  
import android.view.View;  
import android.widget.ImageButton;  
import android.widget.ImageView;  
import android.widget.LinearLayout;  
import org.winplus.thum.R;  

public class ThumbnailsWindows extends LinearLayout {  

private static final String TAG = "ThumbnailsWindows";  
private Context mContext;  
private static ArrayList<String> paths = new ArrayList<String>();  

private ImageView imageView;  

public ThumbnailsWindows(Context context) {  
super(context);  
        mContext = context;  
        setupViews();  
    }  

public ThumbnailsWindows(Context context, AttributeSet attrs) {  
super(context, attrs);  
        mContext = context;  
        setupViews();  
    }  

public void setupViews() {  

/**
         * 显示大图时需要使用，当然可以直接在此类中定义！这样还好控制一些~到时候再改吧，赶这过年呢
         */
final LayoutInflater mLayoutInflater = LayoutInflater.from(getContext());  
        View v = mLayoutInflater.inflate(R.layout.original_photo, null);  
        imageView =  (ImageView) v.findViewById(R.id.original);  

        Map<String,Bitmap> maps = new TreeMap<String, Bitmap>();  
try {  
            maps = buildThum();  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        }  

        Iterator<String> it = maps.keySet().iterator();  
int i = 0;  
while (it.hasNext()) {  
            String path = (String) it.next();    
            Bitmap bm = maps.get(path);    

            ImageButton image = new ImageButton(mContext);   
            image.setImageBitmap(bm);  
            image.setId(i++);  
            addView(image);  
            image.setOnTouchListener(listener);  
        }  

        addView(v);  
    }  

/**
     * 定义按钮控件的Touch事件
     */
    OnTouchListener listener = new OnTouchListener() {  
@Override
public boolean onTouch(View v, MotionEvent event) {  
/**
             * 控件按下的时候显示当前略缩图的大图
             */
if(event.getAction() == MotionEvent.ACTION_DOWN){  
                String path = paths.get(v.getId());  
                InputStream inputStream = null;  
try {  
                    inputStream = new FileInputStream(path);  
                } catch (FileNotFoundException e) {  
                    e.printStackTrace();  
                }  
                Bitmap bitmap = BitmapFactory.decodeStream(inputStream);  
                imageView.setImageBitmap(bitmap);  
            }  
return false;  
        }  
    };  

/**
     * 获取图片地址列表
     * @param file
     * @return
     */
private static ArrayList<String> imagePath(File file) {  
        ArrayList<String> list = new ArrayList<String>();  

        File[] files = file.listFiles();  
for (File f : files) {  
            list.add(f.getAbsolutePath());  
        }  
        Collections.sort(list);  
return list;  
    }  

/**
     * 读取sdcard文件夹中的图片，并生成略缩图
     * @return
     * @throws FileNotFoundException
     */
private Map<String,Bitmap> buildThum() throws FileNotFoundException {  
        File baseFile = new File("/mnt/sdcard/tflash/image/");  
// 使用TreeMap，排序问题就不需要纠结了
        Map<String,Bitmap> maps = new TreeMap<String, Bitmap>();  
if (baseFile != null && baseFile.exists()) {  
            paths = imagePath(baseFile);  

if (!paths.isEmpty()) {  
for (int i = 0; i < paths.size(); i++) {  
                     BitmapFactory.Options options = new BitmapFactory.Options();  
                     options.inJustDecodeBounds = true; // 设置了此属性一定要记得将值设置为false
                     Bitmap bitmap =BitmapFactory.decodeFile(paths.get(i),options);  
                     options.inJustDecodeBounds = false;  
int be = options.outHeight/40;  
if (be <= 0) {  
                         be = 10;  
                     }  
                     options.inSampleSize = be;  
                     bitmap = BitmapFactory.decodeFile(paths.get(i),options);  
                     maps.put(paths.get(i), bitmap);  
                }  
            }  
        }  

return maps;  
    }  
}  

修改mail.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<org.winplus.thum.view.ThumbnailsWindows
android:layout_width="fill_parent"
android:layout_height="fill_parent" />

</LinearLayout>

本Demo还有Bug，稍后在修改吧，看能否经过修改，改成像Ihone图片浏览器一样的效果.好了，本文就写到这里，提前预祝各位春节快乐！

源码下载==》

转载自：http://blog.csdn.net/tangcheng_ok