初学Android,闹钟服务调用Service(六十九)

下面的例子是让AlarmManager定时调用某个Service，从而让系统实现定时更换壁纸的功能
界面非常简单



先创建更换壁纸的服务类

package WangLi.Service.AlarmWallpaper;

import android.app.Service;
import android.app.WallpaperManager;
import android.content.Intent;
import android.os.IBinder;

public class ChangeService extends Service {
    //定义定时更新的壁纸资源
	int[] wallpapers = new int[] {
			R.drawable.shuangta,
			R.drawable.lijiang,
			R.drawable.qiao,
			R.drawable.shui
	};
	//定义系统的壁纸管理服务
	WallpaperManager wManager;
	//定义当前所显示的壁纸
	int current = 0;
	@Override
	public void onStart(Intent intent,int startId)
	{
		//如果到了最后一张,系统重头开始
		if(current >= 4)
			current = 0;
		try
		{
			//改变壁纸
			wManager.setResource(wallpapers[current++]);
		}
		catch(Exception e)
		{
			e.printStackTrace();
		}
		super.onStart(intent, startId);
	}
	@Override
	public void onCreate()
	{
		super.onCreate();
		//初始化WallpaperManager
		wManager = WallpaperManager.getInstance(this);
	}
	@Override
	public IBinder onBind(Intent arg0) {
		// TODO Auto-generated method stub
		return null;
	}
}

这里面用到了WallpaperManager这个类，是Android系统里面专门管理墙纸的类
程序里面要加上设置墙纸的权限

<uses-permission android:name="android.permission.SET_WALLPAPER"/>

同时配置上这个service类

<service android:name="ChangeService"></service>

接着在主界面调用这个服务

package WangLi.Service.AlarmWallpaper;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

public class AlarmChangeWallpaper extends Activity {
	// 定义AlarmManager对象
	AlarmManager aManager;
	Button start, stop;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		start = (Button) findViewById(R.id.start);
		stop = (Button) findViewById(R.id.stop);
		aManager = (AlarmManager) getSystemService(Service.ALARM_SERVICE);
		// 指定启动ChangeService组件
		Intent intent = new Intent(AlarmChangeWallpaper.this,
				ChangeService.class);
		// 创建PendingIntent对象
		final PendingIntent pi = PendingIntent.getService(
				AlarmChangeWallpaper.this, 0, intent, 0);
		start.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// 设置每５秒执行pi代表的组件一次
				aManager.setRepeating(AlarmManager.RTC_WAKEUP, 0, 5000, pi);
				start.setEnabled(false);
				stop.setEnabled(false);
				Toast.makeText(AlarmChangeWallpaper.this, "壁纸定时更换启动成功啦", 5000)
						.show();
			}
		});
		stop.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				start.setEnabled(true);
				stop.setEnabled(true);
				//取消对pi的调度
				aManager.cancel(pi);
			}
		});
	}
}

成功设置后，壁纸是５秒更换一次，也可以停止更换的服务