/**
     *判断当前应用程序处于前台还是后台
     * 
     * @param context

* @return

*/

public static boolean isApplicationBroughtToBackground(final Context context) {
        ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
        List<RunningTaskInfo> tasks = am.getRunningTasks(1);
        if (!tasks.isEmpty()) {
            ComponentName topActivity = tasks.get(0).topActivity;
            if (!topActivity.getPackageName().equals(context.getPackageName())) {
                return true;
            }
        }
        return false;

}

上面这段代码是需要一个权限的：

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

下面这段代码是我最新发现，无需权限，妥妥滴：

/**
* 
* @param context
* @return
*/
public static boolean isBackground(Context context) {

ActivityManager activityManager = (ActivityManager) context
.getSystemService(Context.ACTIVITY_SERVICE);
List<RunningAppProcessInfo> appProcesses = activityManager
.getRunningAppProcesses();
for (RunningAppProcessInfo appProcess : appProcesses) {
if (appProcess.processName.equals(context.getPackageName())) {
if (appProcess.importance == RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {
Log.i(String.format("Background App:", appProcess.processName));
return true;
}else{
Log.i(String.format("Foreground App:", appProcess.processName));
return false;
}
}
}
return false;
}