判断程序是否存于前台进程

前些天做项目时，需要加入九宫格解锁功能，当程序处于后台进程时，再进入前台进程，弹出九宫格解锁...开始考虑到是否可以用Activity的生命周期来处理，最后发现，当程序开启了另一个Activity他也会弹出九宫格解锁，要的却不是这个效果:

/**
* 程序是否在前台运行
*
* @return
*/
public boolean isAppOnForeground() {
// Returns a list of application processes that are running on the
// device

ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);
String packageName = getApplicationContext().getPackageName();

List<RunningAppProcessInfo> appProcesses = activityManager
.getRunningAppProcesses();
if (appProcesses == null)
return false;

for (RunningAppProcessInfo appProcess : appProcesses) {
// 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;
}

当程序执行onStop()方法时，判断是否处于后台进程...加上全局的标志

程序执行onResume()方法时，根据已经标志的变量。再做相应的操作...