android 图片缓存lru,使用新式LruCache取代SoftReference缓存图片，Android异步加载图片...

import java.io.InputStream;

import java.net.URL;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Handler;

import android.os.Message;

import android.support.v4.util.LruCache;

import android.util.Log;

public class AsyncImageLoader {

/**

* 使用新式的LruCache取代SoftReference缓存图片，异步加载图片。

*

* 备注：图片的URL作为缓存图片时LruCache的 Key

* */

private final int CACHE_SIZE = 4 * 1024 * 1024; // 4MiB

private final int MESSAGE_WHAT = 201;

private LruCache mMemoryCache;

public AsyncImageLoader() {

mMemoryCache = new LruCache(CACHE_SIZE) {

@Override

protected int sizeOf(String key, Bitmap value) {

return value.getRowBytes() * value.getHeight();

}};

}

public Bitmap loadBitmap(final String imageUrl, final ImageLoadedListener imageLoadedListener)

{

final Handler handler = new Handler() {

@Override

public void handleMessage(Message message) {

switch(message.what)

{

case MESSAGE_WHAT:

imageLoadedListener.imageLoaded((Bitmap) message.obj, imageUrl);

}

}

};

if (mMemoryCache.get(imageUrl)!=null) {

Log.d(this.getClass().getName(),"发现图片缓存，从缓存中读取！");

Bitmap bmp = mMemoryCache.get(imageUrl);

Message message = handler.obtainMessage();

message.what=MESSAGE_WHAT;

message.obj=bmp;

handler.sendMessage(message);

return bmp;

}

Log.d(this.getClass().getName(),"图片没有缓存，从网络加载！");

new Thread() {

@Override

public void run() {

Bitmap bmp = loadBitmapFromUrl(imageUrl);

mMemoryCache.put(imageUrl, bmp);

Message message = handler.obtainMessage();

message.what=MESSAGE_WHAT;

message.obj=bmp;

handler.sendMessage(message);

}

}.start();

return null;

}

public static Bitmap loadBitmapFromUrl(String url) {

Log.d("AsyncImageLoader.loadBitmapFromUrl()","Loading -> "+url);

InputStream is = null;

try {

is = (InputStream) new URL(url).getContent();

} catch (Exception e) {

e.printStackTrace();

}

Bitmap bmp=BitmapFactory.decodeStream(is);

return bmp;

}

public interface ImageLoadedListener {

public void imageLoaded(Bitmap bitmap, String url);

}

}