Handler

發(fā)送message：在工作線程給主線程發(fā)送消息

• sendMessage(Message message)
• sendEmptyMessage(int what)

處理Message：在主線程執(zhí)行時，方法會被回調(diào)，建立通信基礎(chǔ)

• handleMessage(Message msg)
  使用它來發(fā)送message和處理message

Message

工作線程與主線程的發(fā)送的消息
Message通過屬性what arg1 arg2傳遞整型數(shù)據(jù)
setData(Bundle bundle)加載對象型數(shù)據(jù)
Message.obtain(Handler hander)
當looper將消息取出交還給另外的handler

一、發(fā)送一個空的Message，傳遞一個輕量的數(shù)據(jù)；使用what標識

1、繼承Handler，在Activity中寫一個內(nèi)部類，接收消息,在這里更新UI

class MyHandler2 extends Handler{
    @Override
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        textView.setText(msg.what+" ");   
 }}

2 、定義MyHandler2對象,一般為Activity的成員變量

MyHandler2 handler2=new MyHandler2();

3、在工作線程中，使用MyHandler2給UI線程發(fā)送消息

使用sendEmptyMessage(),參數(shù)為int值，傳遞輕量參數(shù)

 public void onClick(View view){
        new Thread(new Runnable() {
            @Override
            public void run() {
                while(i<100){
                    i++;
                    handler2.sendEmptyMessage(i);
                    try {
                        Thread.sleep(80);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

效果圖

    public class HandlerActivity_12_08 extends AppCompatActivity {
    TextView textView;
    MyHandler2 handler2=new MyHandler2();
    int i=0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_handler_activity_12_08);
        textView= (TextView) findViewById(R.id.tvHandler_08);
    }
    public void onClick(View view){
        new Thread(new Runnable() {
            @Override
            public void run() {
                while(i<100){
                    i++;
                    handler2.sendEmptyMessage(i);
                    try {
                        Thread.sleep(80);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }
    class MyHandler2 extends Handler{
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            textView.setText(msg.what+" ");
        }
    }
}