android中的异步，AsyncTask，HandlerThread

Android除了能用java的Thread创建异步任务
android还提供了以下异步工具
1.AsyncTask。在后工作了，可以自定义发给主线程状态，完成时把结果发给主线程。
2.HandlerThread。是android提供的带消息循环的Thread。
// 创建对象，并启动该线程
HandlerThread mHandlerThread = new HandlerThread("sub_thread");
mHandlerThread.start();
// 一定要传刚创建的线程的Looper，要不然handlermessage不再子线程中执行
Handler mHandler = new Handler(mHandlerThread.getLooper());
3.自定义带消息循环的Thread(就是在run函数中加Looper.prepare();Looper.loop();在这两个被调中间定义handler。退出消息循环用 Looper.myLooper().quit())

new AsyncTask<Integer, Integer, Integer>() {protected void onPreExecute() {Log.i(TAG, "异步子线程开始前");}@Overrideprotected Integer doInBackground(Integer... params) {Log.i(TAG, "doInBackground 传参：" + params[0]);for (int i = 0; i < 10; i++) {publishProgress(i);}return 2;}protected void onProgressUpdate(Integer... values) {Log.i(TAG, "doInBackground 更新进度为：" + values[0]);}protected void onPostExecute(Integer result) {Log.i(TAG, "doInBackground 返回结果为：" + result);}}.execute(1);

 class LooperThread extends Thread {          private Handler mHandler;          private final Object mSync = new Object();            public void run() {              Looper.prepare();//加锁是为了 getHandler()不为空，必须的            synchronized (mSync) {                  mHandler = new Handler(){                      @Override                      public void handleMessage(Message msg) {                          Log.d("CYQ", "--->" + msg);                      }                  };                  mSync.notifyAll();              }              Looper.loop();          }                    public Handler getHandler() {              synchronized (mSync) {                  if (mHandler == null) {                      try {                          mSync.wait();                      } catch (InterruptedException e) {                      }                  }                  return mHandler;              }          }          public void exit() {              getHandler().post(new Runnable(){                  public void run() {                      Looper.myLooper().quit();                  }});          }      }

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