程序一:
public class MainActivity extends Activity {
private Button startButton = null;
private Button endButton = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startButton = (Button)findViewById(R.id.startButton);
startButton.setOnClickListener(new StartButtonListener());
endButton = (Button)findViewById(R.id.endButton);
endButton.setOnClickListener(new EndButtonListener());
}
class StartButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
handler.post(updateThread);
}
}
class EndButtonListener implements OnClickListener{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
handler.removeCallbacks(updateThread);
}
}
Handler handler = new Handler();
Runnable updateThread = new Runnable(){
@Override
public void run() {
// TODO Auto-generated method stub
System.out.println("UpdateThread");
handler.postDelayed(updateThread, 3000);
}
};
}
按下启动按钮之后程序将会每隔3000毫秒打印一句"UpdateThread",直到按下结束按钮。
程序二：
main.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ProgressBar
android:id="@+id/bar"
style="?android:attr/progressBarStyleHorizontal" //水平方向的进度条
android:layout_width="200dp"
android:layout_height="wrap_content"
android:visibility="gone" //进度条处于不可见状态
/>
<Button
android:id="@+id/startButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="start"/>
</LinearLayout>
TestBarHandler.java:
public class TestBarHandler extends Activity {
/** Called when the activity is first created. */
//声明控件变量
ProgressBar bar = null;
Button startButton = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//根据控件的ID得到代表控件的对象,并为按钮设置监听器
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) {
// TODO Auto-generated method stub
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(){
@Override
public void handleMessage(Message msg) { //与sendMessage是异步的消息处理，一个只管发 //送，一个只管接收
bar.setProgress(msg.arg1);
Bundle bundle = msg.getData();
updateBarHandler.post(updateThread);
System.out.println("test---->" + bundle.getString("test"));
}
};
//线程类，该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 = i + 10 ;
//得到一个消息对象，Message类是有Android操作系统提供
Message msg = updateBarHandler.obtainMessage();
//将msg对象的arg1参数的值设置为i,用arg1和arg2这两个成员变量传递消息，优点是系统性能消耗较少
msg.arg1 = i ;
Bundle bundle = new Bundle();
bundle.putString("test", "test bundle");
msg.setData(bundle);
try {
//设置当前显示睡眠1秒
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//将msg对象加入到消息队列当中
if( i > 100){
//如果当i的值为100时，就将线程对象从handler当中移除
updateBarHandler.removeCallbacks(updateThread);
System.out.println(">>>>>>");
}else{
updateBarHandler.sendMessage(msg);
System.out.println("<<<<<<");
}
}
};
class MyThread extends Thread{
public void run(){
}
}
}
显示效果：
