Android监听程序进入后台，或者恢复到前台

转载于：https://blog.csdn.net/gouguofei/article/details/7775752

基本思路：
就是让app中所有的activity继承与一个公共的activity（例如：BaseActivity），然后在BaseActivity的onStop()中判断当前程序是否处于后台

1. public class BaseActivity extends Activity {  
2.         @Override  
3.         protected void onStop() {  
4.                 // TODO Auto-generated method stub  
5.                 super.onStop();  
6.    
7.                 if (!isAppOnForeground()) {  
8.                         //app 进入后台  
9.                            
10.                         //全局变量isActive = false 记录当前已经进入后台  
11.                 }  
12.         }  
13.    
14.         @Override  
15.         protected void onResume() {  
16.                 // TODO Auto-generated method stub  
17.                 super.onResume();  
18.    
19.                    
20.                 //if (!isActive) {  
21.                         //app 从后台唤醒，进入前台  
22.                            
23.                         //isActive = true;  
24.                 //}  
25.         }  
26.    
27.         /** 
28.          * 程序是否在前台运行 
29.          *  
30.          * @return 
31.          */  
32.         public boolean isAppOnForeground() {  
33.                 // Returns a list of application processes that are running on the  
34.                 // device  
35.                    
36.                 ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);  
37.                 String packageName = getApplicationContext().getPackageName();  
38.    
39.                 List<RunningAppProcessInfo> appProcesses = activityManager  
40.                                 .getRunningAppProcesses();  
41.                 if (appProcesses == null)  
42.                         return false;  
43.    
44.                 for (RunningAppProcessInfo appProcess : appProcesses) {  
45.                         // The name of the process that this object is associated with.  
46.                         if (appProcess.processName.equals(packageName)  
47.                                         && appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {  
48.                                 return true;  
49.                         }  
50.                 }  
51.    
52.                 return false;  
53.         }  
54. }