Android 线程间通信------handler
16lz
2021-01-23
整合代码
//总结：handler 用于 Android 线程之间的通信public class MainActivity extends AppCompatActivity { final static String TAG1 = "Main"; final static String TAG2 = "Sub"; Handler mHandler, subHandler; HandlerThread handlerThread; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); } private void init() { mHandler = new Handler() { @Override public void handleMessage(Message msg) { Log.d(TAG1, msg.what + " -- " + Thread.currentThread().getName()); } }; handlerThread = new HandlerThread("test_handler"); handlerThread.start(); //子线程从 主线程或其他子线程 收消息，再发回到主线程 subHandler = new Handler(handlerThread.getLooper()) { @Override public void handleMessage(Message msg) { Log.d(TAG2, msg.what + " -- " + Thread.currentThread().getName()); //子线程发送到主线程 mHandler.sendEmptyMessage(msg.what); //subHandler.sendEmptyMessageDelayed(4, 1000);//自己调用自己可以达到计时器的效果 } }; //主线程发送消息到子线程 subHandler.sendEmptyMessage(2); //子线程发送消息到子线程 new Thread(new Runnable() { @Override public void run() { subHandler.sendEmptyMessage(3); //子线程中切换到UI线程 new Handler(Looper.getMainLooper()).post(new Runnable() { @Override public void run() { Log.d("NewThread", Thread.currentThread().getName()); } }); //子线程中切换到UI线程 2 //runOnUiThread 当前线程在UI线程则直接run,不是则用handler发布到事件队列的UI线程 runOnUiThread(new Runnable() { @Override public void run() { Log.d("runOnUiThread", Thread.currentThread().getName()); } }); } }).start(); } @Override protected void onDestroy() { super.onDestroy(); handlerThread.quit(); }}运行结果
D/Sub: 2 -- test_handler //主线程发送信息到子线程D/Sub: 3 -- test_handler //子线程发送信息到子线程D/Main: 2 -- main D/Main: 3 -- main //子线程收到信息发送到主线程D/NewThread: main //子线程切换到主线程D/runOnUiThread: main //子线程切换到主线程runOnUiThread 源码解析
public final void runOnUiThread(Runnable action) { if (Thread.currentThread() != mUiThread) { //当前线程不是UI线程 mHandler.post(action); //利用Activity中的Handler发布到UI线程的事件队列中 } else { action.run(); //当前线程为UI线程，则直接执行 } }