Android异步加载图片并缓存到本地软引用

// FileCache.java
import java.io.File;
import android.content.Context;

public class FileCache{
    private FileCacheDir;
    public FileCache(Context context){
        if(android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
            cacheDir = new File(android.os.Environmet.getExternalStrorageDirectory(),"文件夹名称");
        else
            cacheDir = context.getCacheDir();
        if(!cacheDir.exsts())
            cache.mkdirs();
    }

    public File getFile(String url){
        String fileName = String.valueOf(url.hashCode());
        File file = new File(cacheDir,fileName);
        return file;
    }

    public void clear(){
        File[] files = cacheDir.listFiles();
        if(files == null)
            return;
        for(File file:files)
        {
            file.delete();
        }
    }
}
// HttpUtil.java
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoudException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;

/**
 * Http请求工具类
 */
 public class HttpUtil{
    public static String getResponseStr(String path,Map<String,String>parameters){
        StringBuffer buffer = new StringBuffer();
        URL url;
        try{
            if(parameters!=null&&parameters.isEmpty()){
                for(Map.Entry<String,String>entry:parameters.entrySet()){
                    buffer.append(entry.getKey()).append("=").append(URLEncoder.encode(entry.getValue(),"UTF-8")).append("&");
            }
            buffer.deleteCharAt(buffer.length()-1);
        }
        url = new URL(path);
        HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
        urlConnection.setConnectTimeout(3000);
        urlConnection.SetRequesMethod("POST");
        urlConnection.SetDoInput(true);
        urlConnection.SetDoOutput(true);
        // 
        byte[] mydata = buffer.toString().getBytes();
        urlConnection.setRequesProperty("Content-Type","application.x-www-form-urlencoded");
        urlConnection.setRequesProperty("Content-Length",String.valueOf(mydata.length));
        // 获取输出流，向服务器输出数据
        OutputStream outputStream = urlConnection.getOutputStream();
        outputStream.write(mydata,0,mydata.length());
        outputStream.close();
        int responseCode = urlConnection.getResponseCode();
        if(responseCode == 200){
            return changeInuptstream(urlConnection.getInputStream());
        }catch(UnsupportedEncodingException e){
            e.printStackTrace();
        }catch(MalformedURLException e){
            e.printStackTrace();
        }catch(ProtocolException e){
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }
        retun null;
    }
    private static String changeInputStream(InputStream inputStream){
        ByteArrayOutpoutStream outputStream = new ByteArrayOutputStream();
        byte[] data = new byte[1024];
        int len = 0;
        String result = "";
        if(inputStream != null){
            try{
                while((len = inputStream.read(data)) != -1){
                    outputStream.write(data,0,len);
                }
                result = new String(outputStream.toByteArray(),"UTF-8");
            }catch(IOException){
                e.printStacckTrace();
            }
        }
    return result;
    }
    public static InputStream getInputStream(String path){
        URL url;
        try{
            url = new URL(path);
            HttpURLConnection urlConnection = (HttpURLConnection)url.open.Connection();
            urlConnecation.setConnectTimeout(3000);
            urlConnecation.setRequestMethod("GET");
            urlConnecation.setDoInput(true);
            urlConnecation.connect();
            if(urlConnection.getResponseCode == 200)
                return urlConnection.getInputStream();
        }catch(MalformedURLException e){
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }catch(Exception e){
            e.printStacjTrace();
        }
        return null;
    }
    public satatic byte[] readStream(InputStream inStream)throwsException{
        ByteArrayOutputStream outSteam = newByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;
        while((len = inStream.read(buffer)) != -1){
            outStream.write(buffer,0,len);
        }
        outStream.close();
        inStream.close();
        return outStream.toByteArray();
    }
    public static void copyStream(String url,File f){
        FileOutputStream fileOutputStream = null;
        InputStream inputStream = null;
        try{
            inputStream = getInputStream(url);
            byte[] data = new byte[1024];
            int len = 0;
            fileOutputStream = new FileOutputStream(f);
            while((len = inputStream.read(data)) != -1){
                fileOutputStream.write(data,0,len);
            }
        }catch(FileNotFoundException e){
            e.printStackTrace();
        }catch(IOException e){
            e.printStackTrace();
        }finally{
            if(inputStream != null){
                try{
                    inputStream.close();
                }catch(IOException e){
                    e.printStackTrace();
                }
            }
        }
    }
}
// MemoryCache.java
import java.lang.ref.SoftReference;
import java.util.Collections;
import jave.util.HashMap;
import java.util.Map;
import android.graphics.Bitmap;

public class MemoryCache{
    private Map<String,SoftReference<Bitmap>> cache = Collections.sycnchronizedMap(newHashMap<String,SoftReference<Bitmap>>());//软引用

    public Bitmapget(String id){
        if(!cache.containsKey(id))
            return null;
        SoftReference<Bitmap> ref = cache.get(id);
        return ref.get();
    }
    public void put(String id,Bitmap bitmap){
        cache.put(id,newSoftReferce<Bitmap>(bitmap));
    }
    public void clear(){
        cache.clear();
    }
}
// ImageLoader.java
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.UnsupportedEncodingException;
import java.io.net.URLEncoder;
import java.io.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.grapgics.BitmapFactory;
import android.grapgics.drawable.BitmapDrawable;
import android.widget.ImageView;

public class ImageLoader{
    private MemoryCachemoryCache = new MemoryCache();
    private FileCache fileCache;
    private Map<ImageView,String> imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView,String>());
    private ExecutorService executorService;
    private boolean isSrc;

    public ImageLoader(Context context,boolean flag){
        fileCache = new FileCache(context);
        executorService = Executors.newFixedThreadPool(5);
        isSrc = flag;
    }
    final int stub_id = R.drawable.ic_launcher;
    public void DisplayImage(String url,ImageView imageView){
        String u1 = url.substring(0,url.lastIndexOf("/")+1);
        String u2 = url.substring(url,lastIndexOf("/")+1);
        try{
            u2 = URLEncoder.encode(u2,"UTF-8");
        }catch(UnsupportedEncodingException e){
            e.printStackTrace();
        }
        url = u1 +u2;
        imageViews.put(imageView,rul);
        Bitmap bitmap = memoryCache.get(url);
        if(bitmap != null){
            if(isSrc)
                imageView.setImageBitmap(bitmap);
            else
                imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));
        }else{
            queuePhoto(url,imageView);
            if(isSrc)
                imageView.setImageResouce(stub_id);
            else
                imageView.setBackgroundResource(stub_id);
        }
    }
    private void ququePhoto(String url,ImageView imageView){
        PhotoToLoad p = new PhotoToLoad(url,imageView);
        executoService.submit(new PhotoSLoader(p));
    }
    private Bitmap getBitmap(String url){
        try{
            File f = filCache.getFile(url);
            // SD卡
            Bitmap b = onDecodeFile(f);
            if(b != null)
                return b;
            // 从网络
            Bitmap bitmap = null;
            Sysytem.out.println("ImageLoader-->download");
            HttpUtil.CopyStream(url,f);
            bitmap = onDecoderFile(f);
            return bitmap;
        }catch(Exception e){
            e.printStackTrace();
            return null;
        }
    }
    public Bitmap onDecodeFile(File f){
        try{
            return BitmapFactory.decodeStream(new FileInputStream(f));
        }catch(FileNotFoundException e){
            e.printStackTrace();
        }
        return null;
    }
    // 解码图像用来减少内存消耗
    public Bitmap decodeFile(File f){
        try{
            // 解码图像大小
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(new FileInputStream(f),null,o);
            // 找到正确的刻度值，它应该是2的幂
            final int REQUIRED_SIZE = 70;
            int width_tmp = o.outWidth,height_tmp = o.outHeight;
            int scale = 1;
            while(true){
                if(width_tmp/2 < REQUIRED_SIZE || height_tmp/2 < REQUIRED_SIZE)
                break;
                width_tmp /= 2;
                height_tmp /= 2;
                scale *= 2;
            }
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize = scale;
            return BitmapFactory.decodeStream(new FileInputStream(f),null,o2);
        }catch(FileNotFoundException e){

        }
        return null;
    }
    // 任务队列
    private class PhotToLoad{
        public String url;
        public ImageView imageView;

        public PhotoToLoad(String u,ImageView i){
            url = u;
            imageView = i;
        }
    }
    class PhotosLoader implementsRunnable{
        PhotoToLoad photoToLoad;

        PhotoLoader(PhotoToLoad photoToLoad){
            this.photoToLoad = photoToLoad;
        }
        @Override
        public void run(){
            if(imageViewReused(photoToLoad))
                return;
            Bitmap bmp = getBitMap(photoToLoad.url);
            memoryCache.put(photoToLoade.url.bmp);
            if(imageViewReused(photoToLoade))
                return;
            BitmapDisplayer bd = new BitmapDisplayer(bmp,photoToLoad);
            Activity a = (Activity)photoToLoad.imageView.getContext();
            a.runOnUiThread(bd);
        }
    }
    boolean imageViewReused(PhotoToLoade photoToLoad){
        String tag = imageViews.get(photoToLoad.imageView);
        if(tag == null ||!tag.equals(pgotoToLoad.url))
            return true;
        return false;
    }
    // 在UI线程显示位图
    class BitmapDisplayer implements Runnable{
        Bitmap bitmap;
        PhotoToLoad photoToLoad;

        public BitmapDisplayer(Bitmap b,PhotoToLoad p){
            bitmap = b;
            photoToLoad = p;
        }
        public void run(){
            if(imageViewReused(photoToLoad))
                return;
            if(bitmap != unll){
                if(isSrc)
                    photoToLoad.imageView.setImageResouce(stub_id);
                else
                    photoToLoad.imageView.setBackgroundDrawable(new BitmapDrawable(bitmao));
            }else{
                if(isSrc)
                    photoToLoad.imageView.setImageResouce(stub_id);
                else
                    photoToLoad.imageView.setBackgroundDrawable(new BitmapDrawable(bitmao));
            }
        }
    }
    public void clearCache(){
        memoryCache.clear();
        fileCache.clear();
    }
}