Android(安卓)HandlerThread源码解析

作为Android开发者都知道在子线程中使用Handler必须要创建Looper，其实HandlerThread就是在线程中封装了Looper的创建和循环，不用我们开发者自己去创建它，下面我们来看看源码

源码

public class HandlerThread extends Thread {    int mPriority;    int mTid = -1;    Looper mLooper;    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();        }        Process.setThreadPriority(mPriority);        onLooperPrepared();        Looper.loop();        mTid = -1;    }

可以看出它就是一个普通的线程，创建的时候设置优先级，我们来看看它的run方法，挑重点看

 //创建looper，保存到ThreadLocal线程中 Looper.prepare(); synchronized (this) {      //得到创建的Looper      mLooper = Looper.myLooper();      notifyAll();  }  Process.setThreadPriority(mPriority);  onLooperPrepared();  //启动循环Looper中的消息队列  Looper.loop();

很简单，就是创建了Looper并且启动循环消息队列。

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; }

得到刚才创建的Looper对象。

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

释放Looper消息队列里的消息。

到此HandlerThread的源码就解析完了。

源码

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