Android控件Chronometer定时器的实现方法

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:padding="4dip"
 android:gravity="center_horizontal"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

 <Chronometer android:id="@+id/chronometer"
 android:format="Initial format: "
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_weight="0"
 android:paddingBottom="30dip"
 android:paddingTop="30dip"
 />

 <Button android:id="@+id/start"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" 
 android:text="开始">
 <requestFocus />
 </Button>

 <Button android:id="@+id/stop"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" 
 android:text="停止">
 </Button>

 <Button android:id="@+id/reset"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" 
 android:text="重置">
 </Button>

 <Button android:id="@+id/set_format"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" 
 android:text="设置格式">
 </Button>

 <Button android:id="@+id/clear_format"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content" 
 android:text="清除格式">
 </Button>

</LinearLayout> 

package wjq.WidgetDemo;

import android.app.Activity;
import android.os.Bundle;
import android.os.SystemClock;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Chronometer;

public class ChronometerDemo extends Activity {
private Chronometer mChronometer;
 /* (non-Javadoc)
 * @see android.app.Activity#onCreate(android.os.Bundle)
 */
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 // TODO Auto-generated method stub
 super.onCreate(savedInstanceState);
 setContentView(R.layout.chronometerpage);
 Button button;

 mChronometer = (Chronometer) findViewById(R.id.chronometer);

 // Watch for button clicks.
 button = (Button) findViewById(R.id.start);
 button.setOnClickListener(mStartListener);

 button = (Button) findViewById(R.id.stop);
 button.setOnClickListener(mStopListener);

 button = (Button) findViewById(R.id.reset);
 button.setOnClickListener(mResetListener);

 button = (Button) findViewById(R.id.set_format);
 button.setOnClickListener(mSetFormatListener);

 button = (Button) findViewById(R.id.clear_format);
 button.setOnClickListener(mClearFormatListener);
 }

 View.OnClickListener mStartListener = new OnClickListener() {
 public void onClick(View v) {
 mChronometer.start();
 }
 };

 View.OnClickListener mStopListener = new OnClickListener() {
 public void onClick(View v) {
 mChronometer.stop();
 }
 };

 View.OnClickListener mResetListener = new OnClickListener() {
 public void onClick(View v) {
 mChronometer.setBase(SystemClock.elapsedRealtime());
 }
 };

 View.OnClickListener mSetFormatListener = new OnClickListener() {
 public void onClick(View v) {
 mChronometer.setFormat("Formatted time (%s)");
 }
 };

 View.OnClickListener mClearFormatListener = new OnClickListener() {
 public void onClick(View v) {
 mChronometer.setFormat(null);
 }
 };
}