Android 判断程序前后台状态

AppStatusService

package org.wp.activity;

import java.util.List;

import android.app.ActivityManager;
import android.app.ActivityManager.RunningAppProcessInfo;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;

public class AppStatusService extends Service {
	private static final String TAG = "AppStatusService";
	private ActivityManager activityManager;
	private String packageName;

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

	@Override
	public int onStartCommand(Intent intent, int flags, int startId) {
		activityManager = (ActivityManager) this.getSystemService(Context.ACTIVITY_SERVICE);
		packageName = this.getPackageName();
		new Thread() {
			public void run() {
				try {
					while (true) {
						Thread.sleep(1000);
						if (isAppOnForeground()) {
							Log.i(TAG, "true");
						} else {
							Log.i(TAG, "false");
						}
					}
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}.start();
		return super.onStartCommand(intent, flags, startId);
	}

	private boolean isAppOnForeground() {
		// Returns a list of application processes that are running on the device
		List<RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
		if (appProcesses == null) return false;
		for (RunningAppProcessInfo appProcess : appProcesses) {
			// importance:
			// The relative importance level that the system places 
			// on this process.
			// May be one of IMPORTANCE_FOREGROUND, IMPORTANCE_VISIBLE, 
			// IMPORTANCE_SERVICE, IMPORTANCE_BACKGROUND, or IMPORTANCE_EMPTY.
			// These constants are numbered so that "more important" values are
			// always smaller than "less important" values.
			// processName:
			// The name of the process that this object is associated with.
			if (appProcess.processName.equals(packageName)
					&& appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
				return true;
			}
		}
		return false;
	}
}