1、通过RunningTaskInfo类判断（需要额外权限）：

复制代码 代码如下:
/**
*判断当前应用程序处于前台还是后台
*/
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;

}

需要在AndroidMenitfest.xml文件中添加以下权限

复制代码 代码如下:
<uses-permission android:name="android.permission.GET_TASKS" />

2、通过RunningAppProcessInfo类判断（不需要额外权限）：
复制代码 代码如下:
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("后台", appProcess.processName);
return true;
}else{
Log.i("前台", appProcess.processName);
return false;
}
}
}
return false;
}