HandlerThread分析

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.

1。看source code (省略部分)

 public class HandlerThread extends Thread {

     int mTid = -1;
     Looper mLooper;

       /**
      * Call back method that can be explicitly overridden if needed to execute some
      * setup before Looper loops.
      */
     protected void onLooperPrepared() {                                                  //注意这个方法
     }

     public void run() {
         mTid = Process.myTid();
         Looper.prepare();
         synchronized (this) {
             mLooper = Looper.myLooper();
             notifyAll();
         }
         Process.setThreadPriority(mPriority);
         onLooperPrepared();                                                            //调用上面的方法
         Looper.loop();
         mTid = -1;
     }

     /**
      * This method returns the Looper associated with this thread. If this thread not been started
      * or for any reason is isAlive() returns false, this method will return null. If this thread
      * has been started, this method will block until the looper has been initialized.
      * @return The looper.
      */
     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();
                 } catch (InterruptedException e) {
                 }
             }
         }
         return mLooper;
     }

 }