getSystemService是Android很重要的一个API，它是Activity的一个方法，根据传入的NAME来取得对应的Object，然后转换成相应的服务对象。下面介绍系统相应的服务：
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代码示例，使用判断网络连接是否可用，并判断是否是wifi：
protected int checkNetworkInfo() {
ConnectivityManager con = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkinfo = con.getActiveNetworkInfo();
if (networkinfo == null || !networkinfo.isAvailable()) {
// 当前网络不可用
return 1;
}
boolean wifi = con.getNetworkInfo(ConnectivityManager.TYPE_WIFI)
.isConnectedOrConnecting();
if (wifi) {
// 使用wifi上网
return 2;
}
return 3;
}
转载：获取Android正在运行的任务和服务
检测某ActivityUpdate是否在当前Task的栈顶
public static boolean isTopActivy(String cmdName, Context context)
{
ActivityManager manager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<RunningTaskInfo> runningTaskInfos = manager.getRunningTasks(Integer.MAX_VALUE);
String cmpNameTemp = null;
if (null != runningTaskInfos)
{
cmpNameTemp = (runningTaskInfos.get(0).topActivity).toString();
} if (null == cmpNameTemp)
{
return false;
} return cmpNameTemp.equals(cmdName); }
判断Android应用是否在前台
public static boolean isAppOnForeground(Context context)
{
ActivityManager activityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
String packageName = context.getPackageName();
List<RecentTaskInfo> appTask = activityManager.getRecentTasks(Integer.MAX_VALUE, 1); if (appTask == null)
{
return false;
} if (appTask.get(0).baseIntent.toString().contains(packageName))
{
return true;
}
return false;
}
获取Android手机内安装的所有桌面
private static List<String> getAllTheLauncher(Context context)
{
List<String> names = null;
PackageManager pkgMgt = context.getPackageManager();
Intent it = new Intent(Intent.ACTION_MAIN);
it.addCategory(Intent.CATEGORY_HOME);
List<ResolveInfo> ra = pkgMgt.queryIntentActivities(it, 0);
if (ra.size() != 0)
{
names = new ArrayList<String>();
}
for (int i = 0; i < ra.size(); i++)
{
String packageName = ra.get(i).activityInfo.packageName;
names.add(packageName);
}
return names;
}
Android 判断程序前后台状态
public static boolean isLauncherRunnig(Context context)
{
boolean result = false;
List<String> names = getAllTheLauncher(context);
ActivityManager mActivityManager = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);
List<ActivityManager.RunningAppProcessInfo> appList = mActivityManager.getRunningAppProcesses();
for (RunningAppProcessInfo running : appList)
{
if (running.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND)
{
for (int i = 0; i < names.size(); i++)
{
if (names.get(i).equals(running.processName))
{
result = true;
break;
}
}
}
}
return result;
}