详解Android Chronometer控件实现计时器函数

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"   android:layout_width="fill_parent"   android:layout_height="fill_parent"   android:background="@drawable/back"   android:gravity="center"   android:orientation="vertical" >    <LinearLayout     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:layout_margin="10dip"     android:orientation="horizontal" >      <TextView       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_weight="4"       android:gravity="center"       android:text="设置时间:" />      <EditText       android:id="@+id/edt_settime"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_weight="1"       android:inputType="number" />   </LinearLayout>    <Chronometer     android:id="@+id/chronometer"     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:gravity="center"     android:textColor="#ff0000"     android:textSize="60dip" />    <LinearLayout     android:layout_width="fill_parent"     android:layout_height="wrap_content"     android:layout_margin="10dip"     android:orientation="horizontal" >      <Button       android:id="@+id/btnStart"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_weight="1"       android:text="开始记时" />      <Button       android:id="@+id/btnStop"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_weight="1"       android:text="停止记时" />      <Button       android:id="@+id/btnReset"       android:layout_width="fill_parent"       android:layout_height="wrap_content"       android:layout_weight="1"       android:text="重置" />   </LinearLayout>  </LinearLayout> 

package com.jiahui.chronometer;   import android.app.Activity;  import android.app.AlertDialog;  import android.app.Dialog;  import android.content.DialogInterface;  import android.os.Bundle;  import android.os.SystemClock;  import android.text.format.Time;  import android.view.View;  import android.widget.Button;  import android.widget.Chronometer;  import android.widget.EditText;   public class ChronometerDemoActivity extends Activity {     private int startTime = 0;     public void onCreate(Bundle savedInstanceState) {      super.onCreate(savedInstanceState);      setContentView(R.layout.main);       final Chronometer chronometer = (Chronometer) findViewById(R.id.chronometer);       Button btnStart = (Button) findViewById(R.id.btnStart);       Button btnStop = (Button) findViewById(R.id.btnStop);       Button btnRest = (Button) findViewById(R.id.btnReset);       final EditText edtSetTime = (EditText) findViewById(R.id.edt_settime);       btnStart.setOnClickListener(new View.OnClickListener() {         @Override       public void onClick(View v) {           System.out.println("--开始记时---");          String ss = edtSetTime.getText().toString();          if (!(ss.equals("") && ss != null)) {            startTime = Integer.parseInt(edtSetTime.getText()                .toString());          }          // 设置开始讲时时间          chronometer.setBase(SystemClock.elapsedRealtime());          // 开始记时          chronometer.start();         }      });       btnStop.setOnClickListener(new View.OnClickListener() {        @Override       public void onClick(View v) {          // 停止          chronometer.stop();        }       });       // 重置      btnRest.setOnClickListener(new View.OnClickListener() {        @Override       public void onClick(View v) {          chronometer.setBase(SystemClock.elapsedRealtime());         }       });      chronometer          .setOnChronometerTickListener(new Chronometer.OnChronometerTickListener() {            @Override           public void onChronometerTick(Chronometer chronometer) {              // 如果开始计时到现在超过了startime秒              if (SystemClock.elapsedRealtime()                  - chronometer.getBase() > startTime * 1000) {                chronometer.stop();                // 给用户提示                showDialog();              }            }          });    }     protected void showDialog() {      AlertDialog.Builder builder = new AlertDialog.Builder(this);       builder.setIcon(R.drawable.eb28d25);      builder.setTitle("警告").setMessage("时间到")          .setPositiveButton("确定", new DialogInterface.OnClickListener() {            @Override           public void onClick(DialogInterface dialog, int which) {            }          });       AlertDialog dialog = builder.create();      dialog.show();    }  }