又优化了一上Android ListView 异步加载图片(续)

又优化了一下Android 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() {

			@Override
			public void run() {
				if (!mAllowLoad) {
					synchronized (lock) {
						try {
							DebugUtil.debug("wait start.....");
							lock.wait();
							DebugUtil.debug("wait end.....");
						} catch (InterruptedException e) {
							// TODO Auto-generated catch block
							e.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() {
					@Override
					public 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() {
				@Override
				public void run() {
					if (mAllowLoad) {
						mListener.onImageLoad(mt, d);
					}
				}
			});
		} catch (IOException e) {
			handler.post(new Runnable() {
				@Override
				public 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;
		}

	}
}