Android之Handler有感(三)

主线程给主线程发送消息：

public class mainSendToMain extends Activity { private Button btnTest; private TextView textView; private Handler handler; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnTest = (Button)this.findViewById(R.id.btn_01); textView = (TextView)this.findViewById(R.id.view_01); btnTest.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { Looper looper = Looper.getMainLooper(); //getMainLooper()方法是返回主线程的Looper对象 //这里以主线程的Looper对象创建了handler， //所以，这个handler发送的Message会被传递给主线程的MessageQueue。 handler = new MyHandler(looper); //构建Message对象 //第一个参数：是自己指定的message代号，方便在handler选择性地接收 //第二三个参数是传递的整型值，对内存消耗较少 //第四个参数需要封装的对象 Message msg = handler.obtainMessage(1,2,3,"主线程发消息了"); handler.sendMessage(msg); //发送消息 } }); } class MyHandler extends Handler{ public MyHandler(Looper looper){ super(looper); } public void handleMessage(Message msg){ textView.setText("我是主线程的Handler，收到了消息："+msg.obj); } }
其他线程给自己发送消息：

public class otherSendToIts extends Activity{

private Button btnTest; private TextView textView; private Handler handler; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnTest = (Button)this.findViewById(R.id.btn_01); textView = (TextView)this.findViewById(R.id.view_01); btnTest.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { //启动线程 new MyThread().start(); } }); } class MyHandler extends Handler{ public MyHandler(Looper looper){ super(looper); } public void handleMessage(Message msg){ super.handleMessage(msg); textView.setText((String)msg.obj); } } class MyThread extends Thread{ public void run(){ Looper.prepare(); //创建该线程的Looper对象 handler = new ThreadHandler(Looper.myLooper()); //这里Looper.myLooper()获得的就是该线程的Looper对象了 Message msg = handler.obtainMessage(1,1,1,"我自己"); handler.sendMessage(msg); Looper.loop(); } //定义线程类中的消息处理类 class ThreadHandler extends Handler{ public ThreadHandler(Looper looper){ super(looper); } public void handleMessage(Message msg){ //这里对该线程中的MessageQueue中的Message进行处理 //这里我们再返回给主线程一个消息 //加入判断看看是不是该线程自己发的信息 if(msg.what == 1 && msg.obj.equals("我自己")){ handler = new MyHandler(Looper.getMainLooper()); Message msg2 = handler.obtainMessage(1,1,1,"禀告主线程:我收到了自己发给自己的Message"); handler.sendMessage(msg2); } } } } }

其他线程给主线程发送消息：

public class otherSendToMain extends Activity{

private Button btn; private TextView textView; private Handler handler; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.main); btn = (Button) findViewById(R.id.btn_01); textView = (TextView) findViewById(R.id.view_01); btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub new MyThread().start(); } }); } class MyHandler extends Handler{ public MyHandler(Looper looper){ super(looper); } @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); textView.setText("我是主线程的Handler，收到了消息："+(String)msg.obj); } } class MyThread extends Thread{ public void run(){ Looper looper = Looper.getMainLooper(); handler = new MyHandler(looper); Message message = handler.obtainMessage(1,2,3,"其他线程发消息了"); handler.sendMessage(message); } }}

主线程给其他线程发送消息：

public class mainSendToOther extends Activity { Button button3; TextView textView; Looper mainLooper; // 其它线程 OtherHandler otherHandler; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); button3 = (Button) findViewById(R.id.btn_01); textView = (TextView) findViewById(R.id.view_01); button3.setOnClickListener(new OnClickListener(){ @Override public void onClick(View v) { // TODO Auto-generated method stub Message msg =otherHandler.obtainMessage(1,"这是主线程发送的消息"); otherHandler.sendMessage(msg); }}); MyThread thread = new MyThread(); thread.start(); } class MyThread extends Thread { @Override public void run() { // TODO Auto-generated method stub super.run(); //创建该线程的Looper对象，用于接收消息 Looper.prepare(); //线程的looper创建的handler表示消息接收者是子线程 otherHandler = new OtherHandler(Looper.myLooper()); //循环从MessageQueue中取消息。 Looper.loop(); } } class OtherHandler extends Handler { public OtherHandler() { // TODO Auto-generated constructor stub } public OtherHandler(Looper looper) { // TODO Auto-generated constructor stub super(looper); } @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); mainHandler = new MainHandler(Looper.getMainLooper()); Message message = new Message(); message.obj="子线程收到消息"; mainHandler.sendMessage(message); } } MainHandler mainHandler; class MainHandler extends Handler { public MainHandler() { // TODO Auto-generated constructor stub } public MainHandler(Looper looper) { // TODO Auto-generated constructor stub super(looper); } @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); textView.setText("我是主线程，这是收到的消息："+msg.obj); } } }