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我正在编写一个在后台执行某些操作（即服务）的小型 android 应用程序，我希望它在每隔“x”分钟后显示一条 toast 消息。我该如何使用广播监听器和警报管理器来做这件事。有人可以写一个示例代码来演示它。

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1 回答 1

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您可以通过在课堂上使用Timer和轻松做到这一点。TimerTaskService

1.在您的Service类中，首先创建一个内部类DisplayToastTimerTask，扩展 from TimerTask以显示Toast消息。您必须使用HandlerwithRunnable来显示Toastfrom TimerTask：

private class DisplayToastTimerTask extends TimerTask {

    Handler mHandler = new Handler();

    @Override
    public void run() {

        // Do something....

        mHandler.post(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(getApplicationContext(), 
                               "Hello world", Toast.LENGTH_SHORT).show();
            }
        });

    }
}

2.用于Timer安排DisplayToastTimerTask重复执行的时间间隔为2 min 

private static final int TIMER_INTERVAL = 120000; // 2 Minute
private static final int TIMER_DELAY = 0;

// Create new Timer
Timer mTimer = new Timer();
mTimer.scheduleAtFixedRate(new DisplayToastTimerTask(), TIMER_DELAY, TIMER_INTERVAL);

例子：

#. 这是完全的工人阶级Service：**

//MyService.java

import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.widget.Toast;
import java.util.Timer;
import java.util.TimerTask;

public class MyService extends Service {

    private Timer mTimer;
    private Handler mHandler = new Handler();

    private static final int TIMER_INTERVAL = 120000; // 2 Minute
    private static final int TIMER_DELAY = 0;

    @Override
    public void onCreate() {
        super.onCreate();

        if (mTimer != null)
            mTimer = null;

        // Create new Timer
        mTimer = new Timer();

        // Required to Schedule DisplayToastTimerTask for repeated execution with an interval of `2 min`
        mTimer.scheduleAtFixedRate(new DisplayToastTimerTask(), TIMER_DELAY, TIMER_INTERVAL);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        return Service.START_STICKY;
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();

        // Cancel timer
        mTimer.cancel();
    }

    // Required to do some task
    // Here I just display a toast message "Hello world"
    private class DisplayToastTimerTask extends TimerTask {

        @Override
        public void run() {

            // Do something....

            mHandler.post(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(), "Hello world", Toast.LENGTH_SHORT).show();
                }
            });
        }
    }
}

#. 你可以从service下面开始你的喜欢：

Intent intentMyService = new Intent(context, MyService.class);
mContext.startService(intentMyService);

#. 不要忘记将MyService类声明为AndroidManifest.xml：

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

        <service android:name=".MyService" />

    </application>
</manifest>

希望这会有所帮助~

于 2017-06-09T09:31:22.280 回答