Android使用技巧------Activity中怎么样在子线程和UI线程中来回自如

一个方法:runOnUiThreadrunOnUiThread是Activity内部的一个方法,源码如下:/*** Runs the specified action on the UI thread. If the current thread is the UI* thread, then the action is executed immediately. If the current thread is* not the UI thread, the action is posted to the event queue of the UI thread.** @param action the action to run on the UI thread*/public final void runOnUiThread(Runnable action) {if (Thread.currentThread() != mUiThread) {mHandler.post(action);} else {action.run();}}接收参数是一个Runnable,接着判断当前是不是UI线程，如果不是的话就把这一步任务post到UI县城中去执行，如果是UI线程的话就执行这个异步任务。下面是在自己的工程中截取的一个方法：（在一个New的线程run（）中用runOnUiThread（）更新UI。so easy ！）private void getMute() {new Thread() {@Overridepublic void run() {final String mute = mController.getMute(mDevice);runOnUiThread(new Runnable() {@Overridepublic void run() {if (mute == null) {LogUtil.d(TAG, "get mute failed...");//跟新SeekBar的状态if (sb_voice.getProgress() == 0) {initMuteImg(MUTE);}} else {LogUtil.d(TAG, "get mute success");initMuteImg(mute);}}});}}.start();}一个类:HandlerThread上源码：（源码不是很多）/** Copyright (C) 2006 The Android Open Source Project** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at** http://www.apache.org/licenses/LICENSE-2.0 ** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*/package android.os;/*** 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;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() {}@Overridepublic void run() {mTid = Process.myTid();Looper.prepare();synchronized (this) {mLooper = Looper.myLooper();notifyAll();}Process.setThreadPriority(mPriority);onLooperPrepared();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;}/*** Quits the handler thread's looper.* <p>* Causes the handler thread's looper to terminate without processing any* more messages in the message queue.* </p><p>* Any attempt to post messages to the queue after the looper is asked to quit will fail.* For example, the {@link Handler#sendMessage(Message)} method will return false.* </p><p class="note">* Using this method may be unsafe because some messages may not be delivered* before the looper terminates. Consider using {@link #quitSafely} instead to ensure* that all pending work is completed in an orderly manner.* </p>** @return True if the looper looper has been asked to quit or false if the* thread had not yet started running.** @see #quitSafely*/public boolean quit() {Looper looper = getLooper();if (looper != null) {looper.quit();return true;}return false;}/*** Quits the handler thread's looper safely.* <p>* Causes the handler thread's looper to terminate as soon as all remaining messages* in the message queue that are already due to be delivered have been handled.* Pending delayed messages with due times in the future will not be delivered.* </p><p>* Any attempt to post messages to the queue after the looper is asked to quit will fail.* For example, the {@link Handler#sendMessage(Message)} method will return false.* </p><p>* If the thread has not been started or has finished (that is if* {@link #getLooper} returns null), then false is returned.* Otherwise the looper is asked to quit and true is returned.* </p>** @return True if the looper looper has been asked to quit or false if the* thread had not yet started running.*/public boolean quitSafely() {Looper looper = getLooper();if (looper != null) {looper.quitSafely();return true;}return false;}/*** Returns the identifier of this thread. See Process.myTid().*/public int getThreadId() {return mTid;}}首先，HandlerThread是一个Thread，意味这在它的run（）里面跑得任务都是异步。再看其run（），能到通过 Looper.myLooper()获得一个mLooper，还提供了一个getLooper()方法获取这个Looper。熟悉Handler、Looper、Message机制的话，很容一就可以把你想要放在HandlerThread中去，举个栗子：首先创建自己的HandlerThread，让它跑起来：HandlerThread playThread = new HandlerThread("PlayActionManager");playThread.start();接下来就是将其内部的Looper给到目标Handler：PlayControHandler controHandler = new PlayControHandler(playThread.getLooper());好了，你可以尽情地在PlayContorHandler（继承自Handler）中的handleMessage方法中做耗时的事情了。