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点击Start按钮，每隔3秒在Logcat里打印一句话
MainActivity.java
public class MainActivity extends ActionBarActivity {
private Button startButton = null;
private Button endButton = null;
Handler handler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton = (Button) findViewById(R.id.startButton);
endButton = (Button) findViewById(R.id.endButton);
startButton.setOnClickListener(new StartButtonListener());
endButton.setOnClickListener(new EndButtonListener());
}
class StartButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
handler.post(updateThread);
}
}
class EndButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
handler.removeCallbacks(updateThread);
}
}
Runnable updateThread = new Runnable() {
@Override
public void run() {
System.out.println("updateThread");
handler.postDelayed(updateThread, 3000);
}
};
}
点击Start按钮之后每隔11000毫秒进度条增加10%
界面 activity_main.xml
MainActivity.java
public class MainActivity extends ActionBarActivity {
private ProgressBar bar = null;
private Button startButton = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
bar = (ProgressBar) findViewById(R.id.bar);
startButton = (Button) findViewById(R.id.startButton);
startButton.setOnClickListener(new ButtonListener());
}
//当点击StartButton按钮时就会执行ButtonListener的onClick方法
class ButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
System.out.println("Onclick");
Toast.makeText(MainActivity.this, "Onclick", Toast.LENGTH_SHORT).show();
bar.setVisibility(View.VISIBLE);
updateBarHandler.post(updateThread);
}
}
//使用匿名内部类来复写Handler当中的handleMessage方法
Handler updateBarHandler = new Handler(){
public void handleMessage(android.os.Message msg) {
bar.setProgress(msg.arg1);
updateBarHandler.post(updateThread);
};
};
//线程类，使用匿名内部类的方式进行声明
Runnable updateThread = new Runnable() {
int i = 0;
@Override
public void run() {
System.out.println("Begin Thread");
i = i + 10;
//得到一个消息对象。Message类是由Android操作系统提供。
Message msg = updateBarHandler.obtainMessage();
//使用arg1和arg2这两个成员变量传递消息，优点是节省系统资源
msg.arg1 = i;
try {
//设置当前线程睡眠一秒
Thread.sleep(1000);
} catch (Exception e) {
e.printStackTrace();
}
//将msg加入到消息队列当中
updateBarHandler.sendMessage(msg);
if (i== 100) {
System.out.println(" i ==100");
updateBarHandler.removeCallbacks(updateThread);
}
}
};
}
可以看到处理消息的线程和主线程是同一个线程
public class MainActivity extends ActionBarActivity {
private Handler handler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
handler.post(runnable);
/*如果采用这种方式则会创建新的线程
Thread thread = new Thread(runnable);
thread.start();
*/
setContentView(R.layout.activity_main);// 要等10秒钟才显示
System.out.println("Activity:" + Thread.currentThread().getId());
System.out.println("ActivityName:" + Thread.currentThread().getName());
}
// 上面打印的信息和下面打印的信息是一样的
// Handler处理线程的时候并没有创建新的线程
Runnable runnable = new Runnable() {
@Override
public void run() {
System.out.println("Handler:" + Thread.currentThread().getId());
System.out.println("HandlerName:"
+ Thread.currentThread().getName());
try {
Thread.sleep(10000);
} catch (Exception e) {
}
}
};
}
在新的线程中处理消息，真正实现异步消息处理
public class MainActivity extends ActionBarActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//打印当前线程的ID
System.out.println("MainActivity>>>" + Thread.currentThread().getId());
//生成一个HandlerThread对象，实现了使用Looper来处理消息队列的功能
HandlerThread handlerThread = new HandlerThread("handler_Thread");
handlerThread.start();
MyHandler myHandler = new MyHandler(handlerThread.getLooper());
Message msg = myHandler.obtainMessage();
//msg.obj = "abc"; //简单数据
Bundle bundle = new Bundle();
bundle.putInt("age", 20);
bundle.putString("name", "umgsai");
msg.setData(bundle);
//将msg发送到目标对象，即生成msg对象的Handler对象
msg.sendToTarget();
}
class MyHandler extends Handler {
public MyHandler() {
}
public MyHandler(Looper looper) {
super(looper);
}
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
//String s = (String) msg.obj; //取出数据
Bundle bundle = msg.getData();
System.out.println("age:" + bundle.getInt("age") + ",name:" + bundle.getString("name"));
System.out.println("Handler>>>" + Thread.currentThread().getId());
System.out.println("handlerMeaage");
}
}
}
当前题目：Android学习笔记-Handler的使用
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