Android多线程与同步- 笔记

Android 的UItoolkit只能在UI线程即主线程被调用,否则会导致CalledFromWrongThreadException。

可以使用AsyncTask来进行一个后台操作(doInBackground),然后在UI线程公开结果,例如在onPostExecute,onProgressUpdate…。

当需要post一个runnable给非主线程时,Android为线程间交互提供了Handler和Looper。Looper线程和HandlerThread类结合使用,可以容易的避免潜在的竞争情况。

importandroid.os.Handler;

importandroid.os.HandlerThread;

importandroid.os.Looper;

importandroid.os.Message;

public classMineHandlerThread extends HandlerThread {

    private Handler handler;

    public MineHandlerThread(String name) {

        super(name);

    }

    public Handler getHandler() {

        return handler;

    }

    @Override

    public void start() {

        super.start();

        Looper looper = getLooper(); // willblock until thread’s Looper object is initialized.

        handler = new Handler(looper) {

            @Override

            public void handleMessage(Messagemsg) {

                switch (msg.what) {

                // process messages here

                }

            }

        };

    }

}

然后可以

        MineHandlerThread thread= new MineHandlerThread("looper thread");

        thread.start();

        Handler handler =thread.getHandler();

        // careful: this couldreturn null if the handler is not initialized

        // yet!

        // to post a runnable

        handler.post(newRunnable() {

            public void run() {

               Log.i("Mine", "Thread? " + Thread.currentThread().getName());

            }

        });

        int what = 0;

        int arg1 = 1;

        int arg2 = 2;

        Message msg =Message.obtain(handler, what, arg1, arg2);

        handler.sendMessage(msg);

        what = 1;

        msg = Message.obtain(handler,what, new Long(Thread.currentThread().getId()));

       handler.sendMessageAtFrontOfQueue(msg);


线程间同步可以使用Synchronized.可以用volatile来处理并发的原子操作,非原子操作的一般都用Synchronized。

在多核的手机上,如果需要,可以通过Runtime.getRuntime().availableProcessors()获得可用的处理器数。然后通过ExecutorService接口,来进行负荷安排,充分利用cpu进行计算。(可参考http://blog.csdn.net/junjieking/article/details/7476850)



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转载自blog.csdn.net/flywalker/article/details/7677946