ActivityManager服务是对Activity管理、运行时功能管理和运行时数据结构的封装，进程(Process)、应用程序/包、服务(Service)、任务(Task)信息等。包括以下功能：
- 激活／去激活activity
- 注册／取消注册动态接受intent
- 发送／取消发送intent
- activity生命周期管理（暂停，恢复，停止，销毁等）
- activity task管理（前台－>后台，后台－>前台，最近task查询，运行时task查询）
- 激活／去激活service
- 激活／去激活provider等
常用内部静态类有：
ActivityManager.MemoryInfo： 系统可用内存信息
ActivityManager.RecentTaskInfo： 最近的任务信息
ActivityManager.RunningAppProcessInfo： 正在运行的进程信息
ActivityManager.RunningServiceInfo： 正在运行的服务信息
ActivityManager.RunningTaskInfo： 正在运行的任务信息
用法：
1.获取ActivityManager服务：
ActivityManager mActivityManager = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
2.获取内存信息：
MemoryInfo memoryInfo = new MemoryInfo() ;
mActivityManager.getMemoryInfo(memoryInfo);
3.获取正在运行的task信息：
List<RunningTaskInfo> runningTaskInfos = mActivityManager.getRunningTasks(Integer.MAX_VALUE);
String cmpNameTemp = null;
if (null != runningTaskInfos)
{
cmpNameTemp = (runningTaskInfos.get(0).topActivity).toString();
}
4.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;
}
5.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;
}
6.判断程序前后台状态：
public static boolean isLauncherRunning(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;
}
7.获取系统中进程信息：
private void getRunningAppProcessInfo() {
processInfoList = new
ArrayList<ProcessInfo>();
List<ActivityManager.RunningAppProcessInfo> appProcessList = mActivityManager.getRunningAppProcesses();
for (ActivityManager.RunningAppProcessInfo appProcessInfo : appProcessList) {
int pid = appProcessInfo.pid;
int uid = appProcessInfo.uid;
String processName = appProcessInfo.processName;
int[] myMempid = new int[] { pid };
Debug.MemoryInfo[] memoryInfo = mActivityManager.getProcessMemoryInfo(myMempid);
int memSize = memoryInfo[0].dalvikPrivateDirty;
Log.i(TAG, "processName: " + processName + " pid: " + pid
+ " uid:" + uid + " memorySize is -->" + memSize + "kb");
// 构造一个ProcessInfo对象
ProcessInfo processInfo = new ProcessInfo();
processInfo.setPid(pid);
processInfo.setUid(uid);
processInfo.setMemSize(memSize);
processInfo.setPocessName(processName);
processInfoList.add(processInfo);
// 获得每个进程里运行的应用程序(包),即每个应用程序的包名
String[] packageList = appProcessInfo.pkgList;
Log.i(TAG, "process id is " + pid + "has " + packageList.length);
for (String pkg : packageList) {
Log.i(TAG, "packageName " + pkg + " in process id is -->"+ pid);
}
}
}