android基础：handler与messag案例（计时器）

 

运行效果

 

代码文件

string.xml

<?xml version="1.0" encoding="utf-8"?>  
<resources>  
    <string name="action_settings">Settings</string>  
    <string name="app_name">计时器</string>  
    <string name="gettime">计时</string>  
    <string name="starttime">开始</string>  
    <string name="stoptime">停止</string>  
    <string name="inputhint">请输入时间</string>  
</resources>  

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical"  
    tools:context="com.mytest.mycounttime.MainActivity" >  
  
    <EditText  
        android:id="@+id/inputTime"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:ems="10"  
        android:hint="@string/inputhint"  
        android:inputType="number" >  
        <requestFocus />  
    </EditText>  
  
    <Button  
        android:id="@+id/getTime"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="@string/gettime" />  
  
    <Button  
        android:id="@+id/startTime"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="@string/starttime" />  
  
    <Button  
        android:id="@+id/stopTime"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content"  
        android:text="@string/stoptime" />  
  
    <TextView  
        android:id="@+id/timeView"  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content" />  
  
</LinearLayout> 

　

activity.java

package com.mytest.mycounttime;  
  
import java.util.Timer;  
import java.util.TimerTask;  
  
import android.app.Activity;  
import android.os.Bundle;  
import android.os.Handler;  
import android.os.Message;  
import android.util.Log;  
import android.view.Menu;  
import android.view.MenuItem;  
import android.view.View;  
import android.widget.Button;  
import android.widget.EditText;  
import android.widget.TextView;  
  
public class MainActivity extends Activity {  
  
    private Button getTimeButton, startTimeButton, stopTimeButton;  
    private EditText inputTimeText;  
    private TextView timeViewText;  
  
    private int inputTime;  
    private int currTime;  
    private Timer timer;  
    private TimerTask timerTask;  
    private Handler handler = new MessageHandler();  
  
    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
  
        // 页面元素赋值  
        initView();  
  
        getTimeButton.setOnClickListener(new TimeButtonOnClickListener());  
        startTimeButton.setOnClickListener(new TimeButtonOnClickListener());  
        stopTimeButton.setOnClickListener(new TimeButtonOnClickListener());  
  
    }  
  
    private void initView() {  
        getTimeButton = (Button) this.findViewById(R.id.getTime);  
        startTimeButton = (Button) this.findViewById(R.id.startTime);  
        stopTimeButton = (Button) this.findViewById(R.id.stopTime);  
        inputTimeText = (EditText) this.findViewById(R.id.inputTime);  
        timeViewText = (TextView) this.findViewById(R.id.timeView);  
    }  
  
    private final class MessageHandler extends Handler {  
  
        @Override  
        public void handleMessage(Message msg) {  
            // timeViewText.setText(currTime);  
            // 显示当前时间  
            timeViewText.setText("时间："+msg.arg1 + "");  
            startTime();  
        }  
  
    }  
  
    private final class TimeButtonOnClickListener implements View.OnClickListener {  
  
        @Override  
        public void onClick(View v) {  
            Log.v("info", "currTime:" + currTime);  
  
            switch (v.getId()) {  
            case R.id.getTime:  
                inputTime = Integer.parseInt(inputTimeText.getText().toString());  
                currTime = inputTime;  
                break;  
  
            case R.id.startTime:  
                startTime();  
                break;  
            case R.id.stopTime:  
                stopTime();  
                break;  
  
            }  
  
        }  
  
    }  
  
    private void stopTime() {  
        timer.cancel();  
  
    }  
  
    private void startTime() {  
  
        timer = new Timer();  
        timerTask = new TimerTask() {  
  
            @Override  
            public void run() {  
  
                Log.v("info", "currTime:" + currTime);  
  
                if (currTime <= 0) {  
                    timer.cancel();  
                    return;  
                }  
  
                currTime--;  
  
                // 发送消息，传送当前时间  
                Message message = handler.obtainMessage();  
                message.arg1 = currTime;  
                handler.sendMessage(message);  
            }  
  
        };  
  
        timer.schedule(timerTask, 1000);  
  
    }  
  
}