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);  

    }  

}