Android提供了Invalidate方法实现界面刷新，但是Invalidate不能直接在线程中调用，因为他是违背了单线程模型：Android UI操作并不是线程安全的，并且这些操作必须在UI线程中调用。

Android程序中可以使用的界面刷新方法有两种，分别是利用Handler和利用postInvalidate()来实现在线程中刷新界面。

利用Handler刷新界面
实例化一个Handler对象，并重写handleMessage方法调用invalidate()实现界面刷新；而在线程中通过sendMessage发送界面更新消息。

复制代码 代码如下:
// 在onCreate()中开启线程

       new Thread(new GameThread()).start();、

       // 实例化一个handler

       Handler myHandler   = new Handler()

       {

              //接收到消息后处理

              public void handleMessage(Message msg)

              {

                     switch (msg.what)

                     {

                     case Activity01.REFRESH:

                            mGameView.invalidate();        //刷新界面

                            break;

                     }

                     super.handleMessage(msg);

              }                  

       };

       class GameThread implements Runnable

       {

              public void run()

              {

                     while (!Thread.currentThread().isInterrupted())

                     {

                            Message message = new Message();

                            message.what = Activity01.REFRESH;

                            //发送消息

                            Activity01.this.myHandler.sendMessage(message);

                            try

                            {

                                   Thread.sleep(100);

                            }

                            catch (InterruptedException e)

                            {

                                   Thread.currentThread().interrupt();

                            }

                     }

              }

       }

使用postInvalidate()刷新界面
使用postInvalidate则比较简单，不需要handler，直接在线程中调用postInvalidate即可。

复制代码 代码如下:
 class GameThread implements Runnable

       {

              public void run()

              {

                     while (!Thread.currentThread().isInterrupted())

                     {

                            try

                            {

                                   Thread.sleep(100);

                            }

                            catch (InterruptedException e)

                            {

                                   Thread.currentThread().interrupt();

                            }

                            //使用postInvalidate可以直接在线程中更新界面

                            mGameView.postInvalidate();

                     }

              }

       }