Android判断当前应用程序处于前台还是后台的两种方法

1、通过runningtaskinfo类判断（需要额外权限）：

/**
     *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

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

2、通过runningappprocessinfo类判断（不需要额外权限）：

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;
}