一、work线程向main线程发送数据(work线程发数据,main线程处理数据)
public class MainActivity extends Activity { private Button button; private TextView textView; private Handler handler; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button = (Button)this.findViewById(R.id.button1); textView = (TextView)this.findViewById(R.id.textView1);
handler = new MyHandler(); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { new Thread(){ @Override public void run() { super.run(); Thread.currentThread().getName();//获取当前线程的名字 Message msg = Message.obtain(); String s = "hello handler"; msg.obj = s; handler.sendMessage(msg); } }.start(); } }); } public class MyHandler extends Handler{ @Override public void handleMessage(Message msg) { super.handleMessage(msg); String s = (String)msg.obj; textView.setText(s); } } }
二、main线程向work线程发送数据(main线程发数据,work线程处理数据)
public class MainActivity extends Activity { private Button button; private TextView textView; private Handler handler; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button = (Button)this.findViewById(R.id.button); textView = (TextView)this.findViewById(R.id.textview); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { Message msg = Message.obtain(); msg.obj = "handler2"; handler.sendMessage(msg); } }); new Thread(){ @Override public void run() { super.run(); Looper.prepare();//第一步 handler = new Handler(){//第二步 @Override public void handleMessage(Message msg) { super.handleMessage(msg); String s = (String) msg.obj; System.out.println(s); } }; Looper.loop();//第三步 } }.start(); } }
三、Handler、Looper、MessageQueue的工作原理
handler可以在任意线程发送消息
一个线程可以有多个Handler,但是只能有一个Looper!