又优化了一下Android(安卓)ListView 异步加载图片(续)

之前发表过一篇文章：又优化了一下 Android ListView 异步加载图片
大家反应还行，不过普遍爆出new Thread太多会导致性能和资源浪费的问题，我想了一下的确如此，有人说用AsyncTask会更好点，因为实现的原理是线程池，肯定是比new Thread强，这个我也没有考证，后来根据自己的一套做了一些修改，只是一直没发出来，然后有些同学线下又找我要修改后的源码，我就索性把我修改的发出来给大家分享一下。

其实改动不大，就是把之前的new Thread改成了 Handler Looper Thread的模式，这样在第一次滑动的时候就进入了wait状态，又因为handler里面的runnable是队列执行的，所以handler一直在添加的runnable也在等待，这样就避免了多次new thread的问题，从头到尾就只有一个thread，别的不多说，看修改后的代码。

源码我就不上传了，就添加了一个类，修改了一个类：

package cindy.android.util;import android.os.Handler;import android.os.Looper;import android.os.Message;public class RunInOtherThread {    private static final String LOG_TAG = "RunInOtherThread";        private LooperThread localThread = new LooperThread();        private boolean isRunning = true;    public Handler getHandler(){    return localThread.getHandler();    }        private class LooperThread extends Thread {        private Handler mHandler;        public void run() {            Looper.prepare();            mHandler = new Handler() {                public void handleMessage(Message msg) {                onReceiveMessage(msg.what);                }            };            Looper.loop();        }                Handler getHandler(){        return mHandler;        }       }        public void start(){    localThread.start();    }        public void quit(){    localThread.getHandler().getLooper().quit();    }        public void sendMessage(int what){    getHandler().sendEmptyMessage(what);    }        public Thread getThread(){    return localThread;    }        public void onReceiveMessage(int what){};     }

package cindy.android.util;import java.io.DataInputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.lang.ref.SoftReference;import java.net.URL;import java.util.HashMap;import cindy.android.debug.DebugUtil;import android.graphics.drawable.Drawable;import android.os.Environment;import android.os.Handler;public class SyncImageLoader {private Object lock = new Object();private boolean mAllowLoad = true;private boolean firstLoad = true;private int mStartLoadLimit = 0;private int mStopLoadLimit = 0;final Handler handler = new Handler();private HashMap<String, SoftReference<Drawable>> imageCache = new HashMap<String, SoftReference<Drawable>>();RunInOtherThread runInOutherThread;public SyncImageLoader() {super();runInOutherThread = new RunInOtherThread();runInOutherThread.start();}public interface OnImageLoadListener {public void onImageLoad(Integer t, Drawable drawable);public void onError(Integer t);}public void setLoadLimit(int startLoadLimit, int stopLoadLimit) {if (startLoadLimit > stopLoadLimit) {return;}mStartLoadLimit = startLoadLimit;mStopLoadLimit = stopLoadLimit;}public void restore() {mAllowLoad = true;firstLoad = true;}public void lock() {mAllowLoad = false;firstLoad = false;}public void unlock() {mAllowLoad = true;synchronized (lock) {lock.notifyAll();}}public void loadImage(Integer t, String imageUrl,OnImageLoadListener listener) {final OnImageLoadListener mListener = listener;final String mImageUrl = imageUrl;final Integer mt = t;runInOutherThread.getHandler().post(new Runnable() {@Overridepublic void run() {if (!mAllowLoad) {synchronized (lock) {try {DebugUtil.debug("wait start.....");lock.wait();DebugUtil.debug("wait end.....");} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}if (mAllowLoad && firstLoad) {loadImage(mImageUrl, mt, mListener);}if (mAllowLoad && mt <= mStopLoadLimit && mt >= mStartLoadLimit) {loadImage(mImageUrl, mt, mListener);}}});}private void loadImage(final String mImageUrl, final Integer mt,final OnImageLoadListener mListener) {if (imageCache.containsKey(mImageUrl)) {SoftReference<Drawable> softReference = imageCache.get(mImageUrl);final Drawable d = softReference.get();if (d != null) {handler.post(new Runnable() {@Overridepublic void run() {if (mAllowLoad) {mListener.onImageLoad(mt, d);}}});return;}}try {final Drawable d = loadImageFromUrl(mImageUrl);if (d != null) {imageCache.put(mImageUrl, new SoftReference<Drawable>(d));}handler.post(new Runnable() {@Overridepublic void run() {if (mAllowLoad) {mListener.onImageLoad(mt, d);}}});} catch (IOException e) {handler.post(new Runnable() {@Overridepublic void run() {mListener.onError(mt);}});e.printStackTrace();}}public static Drawable loadImageFromUrl(String url) throws IOException {//DebugUtil.debug(url);if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {File f = new File(Environment.getExternalStorageDirectory()+ "/TestSyncListView/" + MD5.getMD5(url));if (f.exists()) {FileInputStream fis = new FileInputStream(f);Drawable d = Drawable.createFromStream(fis, "src");return d;}URL m = new URL(url);InputStream i = (InputStream) m.getContent();DataInputStream in = new DataInputStream(i);FileOutputStream out = new FileOutputStream(f);byte[] buffer = new byte[1024];int byteread = 0;while ((byteread = in.read(buffer)) != -1) {out.write(buffer, 0, byteread);}in.close();out.close();Drawable d = Drawable.createFromStream(i, "src");return loadImageFromUrl(url);} else {URL m = new URL(url);InputStream i = (InputStream) m.getContent();Drawable d = Drawable.createFromStream(i, "src");return d;}}}

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