Android Handler 消息机制的日常开发运用与代码测试

很多时候我们需要对每个组件或者所有的UI线程要去负责View的创建并且维护它，例如更新冒个TextView的显示，都必须在主

线程中去做，我们不能直接在UI线程中去创建子线程，要利用消息机制：handler

本篇博客将带大家走进我们熟悉的Handler，顺带写了一个例子来验证Handler的消息机制，Handler通过对子线程的处理，实

现对UI的更新等操作

private TextView time;
            private Handler handler = new Handler(){
            	public void handleMessage(Message msg) {
            		if(msg.what==Reflsh){
            			time.setText(String.valueOf(msg.obj));
            		}
            		super.handleMessage(msg);
            	};
            };
            @Override
            public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            text = getResources().getStringArray(R.array.array);
            for(int i=0;i<text.length;i++){
            	Map<String,Object> map = new HashMap<String, Object>();
            	map.put("img", icon[i]);
            	map.put("name", text[i]);
            	list.add(map);
            }
            adapter = new SimpleAdapter(getActivity(), list, R.layout.log, new String[]{"img","name"}, new int []{R.id.g_icon,R.id.g_text});
            }
			@Override
            public View onCreateView(LayoutInflater inflater, ViewGroup container,
            		Bundle savedInstanceState) {
            	 View view = inflater.inflate(R.layout.fragment_shouye, container, false) ;
            	 gridview = (GridView)view.findViewById(R.id.gridView);
            	 time = (TextView)view.findViewById(R.id.time);//时间
            	 ImageView icon = (ImageView)view.findViewById(R.id.icon);//头像
            	 TextView name = (TextView)view.findViewById(R.id.name);//昵称
//
   				File file = new File(Environment.getExternalStorageDirectory()+"/"+"weiinfo") ;
   				BufferedReader reader = null ;
   				String line = null ;
   				try {
   					 reader = new BufferedReader(new FileReader(file)) ;
   					 line = reader.readLine() ;
   				} catch (Exception e) {
   					e.printStackTrace();
   				}
   	          	 data = line.split("\\*") ;

            	 Picasso.with(getActivity().getApplicationContext()).load(data[5]).into(icon);
            	 name.setText(data[0]);
            	 new Thread(new Runnable() {
					@Override
					public void run() {
						try {
							while(true){
							Thread.sleep(1000);
							Message msg = new Message();
							msg.what = Reflsh;
							msg.obj = new Date(System.currentTimeMillis()).toLocaleString();
							Log.d("XXXXXXXXXXXXXX", msg.obj.toString());
							handler.sendMessage(msg);
							}
						} catch (Exception e) {
							Log.d("异常", ""+e);
						}
					}
				}).start();

上面测试Handler的代码是来自MaoZhuaWeiBo的首页界面的动态北京时间演示，我写了一个Handler来处理我new 出来的子线程，在子线程里我每休眠一秒执行获取一次模拟器当前系统时间，并且将消息发送至Handler处理，Handler将消息更新view同步更新，并且不会阻塞主UI，这就是Handler消息机制的好处！

消息机制打印结果：

一直到关闭这个应用程序为止，打印结果才会停止，这就是Handler的消息机制了~