判断当前应用程序状态是在前台还是后台

public static boolean isBackground(Context context) {

Log.d("Nat: isBackground.packageName1", context.getPackageName());

ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();

for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {

Log.d("Nat: isBackground.processName", appProcess.processName);

if (appProcess.processName.equals(context.getPackageName())) {

Log.d("Nat: isBackground.importance", String.valueOf(appProcess.importance));

if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_BACKGROUND) {

Log.i("后台", appProcess.processName);

return true;

}else{

Log.i("前台", appProcess.processName);

return false;

}

}

}

return false;

}

class ForegroundCheckTask extends AsyncTask<Context, Void, Boolean> {
@Override
protected Boolean doInBackground(Context... params) {
final Context context = params[0].getApplicationContext();
return isAppOnForeground(context);
}
private boolean isAppOnForeground(Context context) {
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager.getRunningAppProcesses();
if (appProcesses == null) {
return false;
}
final String packageName = context.getPackageName();
Log.d("Nat: isAppOnForeground.packageName", context.getPackageName());
for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
Log.d("Nat: isAppOnForeground.processName", appProcess.processName);
if (appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND && appProcess.processName.equals(packageName)) {
return true;
}
}
return false;
}
}

public static boolean isForeground(Context context) {
Log.d("Nat: isBackground.checkPackageName", context.getPackageName());
ActivityManager am  = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningTaskInfo> runningTasks = am.getRunningTasks(1);
if (runningTasks != null){
// The first in the list of RunningTasks is always the foreground task.
ActivityManager.RunningTaskInfo foregroundTaskInfo = runningTasks.get(0);
String foregroundTaskPackageName = foregroundTaskInfo .topActivity.getPackageName();
Log.d("Nat: isBackground.foregroundTaskPackageName", foregroundTaskPackageName);
if (context.getPackageName().equals(foregroundTaskPackageName)){
return true;
}
//            PackageManager pm = context.getPackageManager();
//            PackageInfo foregroundAppPackageInfo = pm.getPackageInfo(foregroundTaskPackageName, 0);
//            String foregroundTaskAppName = foregroundAppPackageInfo.applicationInfo.loadLabel(pm).toString();
}
return false;
}