深入Android HandlerThread 使用及其源码完全解析

HandlerThread handlerThread = new HandlerThread("downloadImage");

//必须先开启线程
 handlerThread.start();

/**
  * 该callback运行于子线程
  */
 class ChildCallback implements Handler.Callback {
  @Override
  public boolean handleMessage(Message msg) {
   //在子线程中进行相应的网络请求
  
   //通知主线程去更新UI
   mUIHandler.sendMessage(msg1);
   return false;
  }
 }

/**
  * 该callback运行于子线程
  */
 class ChildCallback implements Handler.Callback {
  @Override
  public boolean handleMessage(Message msg) {
   //在子线程中进行相应的网络请求
  
   //通知主线程去更新UI
   mUIHandler.sendMessage(msg1);
   return false;
  }
 }

package com.zejian.handlerlooper;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.widget.ImageView;
import com.zejian.handlerlooper.model.ImageModel;
import com.zejian.handlerlooper.util.LogUtils;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
/**
 * Created by zejian on 16/3/5.
 */
public class HandlerThreadActivity extends Activity {
 /**
  * 图片地址集合,图片来自网络.
  */
 private String url[]={
   "http://img.my.csdn.net/uploads/201407/26/1406383299_1976.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383291_6518.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383291_8239.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383290_9329.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383290_1042.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383275_3977.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383265_8550.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383264_3954.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383264_4787.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383264_8243.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383248_3693.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383243_5120.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383242_3127.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383242_9576.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383242_1721.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383219_5806.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383214_7794.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383213_4418.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383213_3557.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383210_8779.jpg",
   "http://img.my.csdn.net/uploads/201407/26/1406383172_4577.jpg"
 };
 private ImageView imageView;
 private Handler mUIHandler = new Handler(){
  @Override
  public void handleMessage(Message msg) {
   LogUtils.e("次数:"+msg.what);
   ImageModel model = (ImageModel) msg.obj;
   imageView.setImageBitmap(model.bitmap);
  }
 };
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_handler_thread);
  imageView= (ImageView) findViewById(R.id.image);
  //创建异步HandlerThread
  HandlerThread handlerThread = new HandlerThread("downloadImage");
  //必须先开启线程
  handlerThread.start();
  //子线程Handler
  Handler childHandler = new Handler(handlerThread.getLooper(),new ChildCallback());
  for(int i=0;i<10;i++){
   //每个1秒去更新图片
   childHandler.sendEmptyMessageDelayed(i,1000*i);
  }
 }
 /**
  * 该callback运行于子线程
  */
 class ChildCallback implements Handler.Callback {
  @Override
  public boolean handleMessage(Message msg) {
   //在子线程中进行网络请求
   Bitmap bitmap=downloadUrlBitmap(url[msg.what]);
   ImageModel imageModel=new ImageModel();
   imageModel.bitmap=bitmap;
   imageModel.url=url[msg.what];
   Message msg1 = new Message();
   msg1.what = msg.what;
   msg1.obj =imageModel;
   //通知主线程去更新UI
   mUIHandler.sendMessage(msg1);
   return false;
  }
 }
 private Bitmap downloadUrlBitmap(String urlString) {
  HttpURLConnection urlConnection = null;
  BufferedInputStream in = null;
  Bitmap bitmap=null;
  try {
   final URL url = new URL(urlString);
   urlConnection = (HttpURLConnection) url.openConnection();
   in = new BufferedInputStream(urlConnection.getInputStream(), 8 * 1024);
   bitmap=BitmapFactory.decodeStream(in);
  } catch (final IOException e) {
   e.printStackTrace();
  } finally {
   if (urlConnection != null) {
    urlConnection.disconnect();
   }
   try {
    if (in != null) {
     in.close();
    }
   } catch (final IOException e) {
    e.printStackTrace();
   }
  }
  return bitmap;
 }
}

/**
 * Handy class for starting a new thread that has a looper. The looper can then be 
 * used to create handler classes. Note that start() must still be called.
 */
public class HandlerThread extends Thread {
 int mPriority;//线程优先级
 int mTid = -1;
 Looper mLooper;//当前线程持有的Looper对象
 public HandlerThread(String name) {
  super(name);
  mPriority = Process.THREAD_PRIORITY_DEFAULT;
 }
 
 /**
  * Constructs a HandlerThread.
  * @param name
  * @param priority The priority to run the thread at. The value supplied must be from 
  * {@link android.os.Process} and not from java.lang.Thread.
  */
 public HandlerThread(String name, int priority) {
  super(name);
  mPriority = priority;
 }
 
 /**
  * Call back method that can be explicitly overridden if needed to execute some
  * setup before Looper loops.
  */
 protected void onLooperPrepared() {
 }

@Override
public void run() {
  mTid = Process.myTid();
  Looper.prepare();
  synchronized (this) {
   mLooper = Looper.myLooper();
   notifyAll(); //唤醒等待线程
  }
  Process.setThreadPriority(mPriority);
  onLooperPrepared();
  Looper.loop();
  mTid = -1;
 }

public Looper getLooper() {
  if (!isAlive()) {
   return null;
  }
  
  // If the thread has been started, wait until the looper has been created.
  synchronized (this) {
   while (isAlive() && mLooper == null) {
    try {
     wait();//等待唤醒
    } catch (InterruptedException e) {
    }
   }
  }
  return mLooper;
 }

public boolean quit() {
  Looper looper = getLooper();
  if (looper != null) {
   looper.quit();
   return true;
  }
  return false;
 }
 public boolean quitSafely() {
  Looper looper = getLooper();
  if (looper != null) {
   looper.quitSafely();
   return true;
  }
  return false;
 }