正如您所写的，该任务是关于监视 3-rd 方应用程序的，除了定期读取进程列表并检测前台进程之外，没有其他解决方案。您需要为此提供服务。不幸的是，Android 没有提供诸如广播事件等手段来改变前台进程。
事实上，该任务需要大量代码，至少比普通答案所能包含的要多得多。我在这里发布了其中的一部分，但您应该解决幕后留下的许多细微差别，例如启动之间的同步和持久信息。这只是一个骨架。
首先，让我们编写一个应用程序对象，这是注册所有与实例相关的东西的好地方。
MonitorApp
public class MonitorApp extends Application
{
// actual store of statistics
private final ArrayList<HashMap<String,Object>> processList = new ArrayList<HashMap<String,Object>>();
// fast-access index by package name (used for lookup)
private ArrayList<String> packages = new ArrayList<String>();
public ArrayList<HashMap<String,Object>> getProcessList()
{
return processList;
}
public ArrayList<String> getPackages()
{
return packages;
}
// TODO: you need to save and load the instance data
// TODO: you need to address synchronization issues
}
然后让我们起草一个活动。
监控活动
import static ProcessList.COLUMN_PROCESS_NAME;
import static ProcessList.COLUMN_PROCESS_PROP;
import static ProcessList.COLUMN_PROCESS_COUNT;
import static ProcessList.COLUMN_PROCESS_TIME;
public class MonitorActivity extends Activity implements MonitorService.ServiceCallback
{
private ArrayList<HashMap<String,Object>> processList;
private MonitorService backgroundService;
private MyCustomAdapter adapter = null;
private ListView listView = null;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main); // TODO: provide your layout
listView = (ListView)findViewById(R.id.id_process_listview);
createAdapter();
this.bindService(
new Intent(this, MonitorService.class),
serviceConnection,
Context.BIND_AUTO_CREATE);
}
private void createAdapter()
{
processList = ((MonitorApp)getApplication()).getProcessList();
adapter = new MyCustomAdapter(this, processList, R.layout.complex_list_item,
new String[]
{
COLUMN_PROCESS_NAME,
COLUMN_PROCESS_PROP, // TODO: you may calculate and pre-fill this field
// from COLUMN_PROCESS_COUNT and COLUMN_PROCESS_TIME
// so eliminating the need to use the custom adapter
},
new int[]
{
android.R.id.text1,
android.R.id.text2
});
listView.setAdapter(adapter);
}
// callback method invoked by the service when foreground process changed
@Override
public void sendResults(int resultCode, Bundle b)
{
adapter.notifyDataSetChanged();
}
private class MyCustomAdapter extends SimpleAdapter
{
MyCustomAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to)
{
super(context, data, resource, from, to);
}
@Override
public View getView (int position, View convertView, ViewGroup parent)
{
View result = super.getView(position, convertView, parent);
// TODO: customize process statistics display
int count = (Integer)(processList.get(position).get(COLUMN_PROCESS_COUNT));
int seconds = (Integer)(processList.get(position).get(COLUMN_PROCESS_TIME));
return result;
}
}
private ServiceConnection serviceConnection = new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName className, IBinder service)
{
LocalBinder binder = (LocalBinder)service;
backgroundService = binder.getService();
backgroundService.setCallback(MonitorActivity.this);
backgroundService.start();
}
@Override
public void onServiceDisconnected(ComponentName className)
{
backgroundService = null;
}
};
@Override
public void onResume()
{
super.onResume();
if(backgroundService != null)
{
backgroundService.setCallback(this);
}
}
@Override
public void onPause()
{
super.onPause();
if(backgroundService != null)
{
backgroundService.setCallback(null);
}
}
}
该活动启动后台工作服务，该服务实际上监控进程。您可以将服务注册从活动移动到应用程序实例中。服务本身是这样的：
监控服务
public class MonitorService extends Service
{
private boolean initialized = false;
private final IBinder mBinder = new LocalBinder();
private ServiceCallback callback = null;
private Timer timer = null;
private final Handler mHandler = new Handler();
private String foreground = null;
private ArrayList<HashMap<String,Object>> processList;
private ArrayList<String> packages;
private Date split = null;
public static int SERVICE_PERIOD = 5000; // TODO: customize (this is for scan every 5 seconds)
private final ProcessList pl = new ProcessList(this)
{
@Override
protected boolean isFilteredByName(String pack)
{
// TODO: filter processes by names, return true to skip the process
// always return false (by default) to monitor all processes
return false;
}
};
public interface ServiceCallback
{
void sendResults(int resultCode, Bundle b);
}
public class LocalBinder extends Binder
{
MonitorService getService()
{
// Return this instance of the service so clients can call public methods
return MonitorService.this;
}
}
@Override
public void onCreate()
{
super.onCreate();
initialized = true;
processList = ((MonitorApp)getApplication()).getProcessList();
packages = ((MonitorApp)getApplication()).getPackages();
}
@Override
public IBinder onBind(Intent intent)
{
if(initialized)
{
return mBinder;
}
return null;
}
public void setCallback(ServiceCallback callback)
{
this.callback = callback;
}
private boolean addToStatistics(String target)
{
boolean changed = false;
Date now = new Date();
if(!TextUtils.isEmpty(target))
{
if(!target.equals(foreground))
{
int i;
if(foreground != null && split != null)
{
// TODO: calculate time difference from current moment
// to the moment when previous foreground process was activated
i = packages.indexOf(foreground);
long delta = (now.getTime() - split.getTime()) / 1000;
Long time = (Long)processList.get(i).get(COLUMN_PROCESS_TIME);
if(time != null)
{
// TODO: add the delta to statistics of 'foreground'
time += delta;
}
else
{
time = new Long(delta);
}
processList.get(i).put(COLUMN_PROCESS_TIME, time);
}
// update count of process activation for new 'target'
i = packages.indexOf(target);
Integer count = (Integer)processList.get(i).get(COLUMN_PROCESS_COUNT);
if(count != null) count++;
else
{
count = new Integer(1);
}
processList.get(i).put(COLUMN_PROCESS_COUNT, count);
foreground = target;
split = now;
changed = true;
}
}
return changed;
}
public void start()
{
if(timer == null)
{
timer = new Timer();
timer.schedule(new MonitoringTimerTask(), 500, SERVICE_PERIOD);
}
// TODO: startForeground(srvcid, createNotification(null));
}
public void stop()
{
timer.cancel();
timer.purge();
timer = null;
}
private class MonitoringTimerTask extends TimerTask
{
@Override
public void run()
{
fillProcessList();
ActivityManager activityManager = (ActivityManager)MonitorService.this.getSystemService(ACTIVITY_SERVICE);
List<RunningTaskInfo> taskInfo = activityManager.getRunningTasks(1);
String current = taskInfo.get(0).topActivity.getPackageName();
// check if current process changed
if(addToStatistics(current) && callback != null)
{
final Bundle b = new Bundle();
// TODO: pass necessary info to UI via bundle
mHandler.post(new Runnable()
{
public void run()
{
callback.sendResults(1, b);
}
});
}
}
}
private void fillProcessList()
{
pl.fillProcessList(processList, packages);
}
}
该服务使用帮助类来构建进程列表。
进程列表
public abstract class ProcessList
{
// process package name
public static final String COLUMN_PROCESS_NAME = "process";
// TODO: arbitrary property (can be user-fiendly name)
public static final String COLUMN_PROCESS_PROP = "property";
// number of times a process has been activated
public static final String COLUMN_PROCESS_COUNT = "count";
// number of seconds a process was in foreground
public static final String COLUMN_PROCESS_TIME = "time";
private ContextWrapper context;
ProcessList(ContextWrapper context)
{
this.context = context;
}
protected abstract boolean isFilteredByName(String pack);
public void fillProcessList(ArrayList<HashMap<String,Object>> processList, ArrayList<String> packages)
{
ActivityManager activityManager = (ActivityManager)context.getSystemService(Context.ACTIVITY_SERVICE);
List<RunningAppProcessInfo> procInfo = activityManager.getRunningAppProcesses();
HashMap<String, Object> hm;
final PackageManager pm = context.getApplicationContext().getPackageManager();
for(int i = 0; i < procInfo.size(); i++)
{
String process = procInfo.get(i).processName;
String packageList = Arrays.toString(procInfo.get(i).pkgList);
if(!packageList.contains(process))
{
process = procInfo.get(i).pkgList[0];
}
if(!packages.contains(process) && !isFilteredByName(process))
{
ApplicationInfo ai;
String applicationName = "";
for(int k = 0; k < procInfo.get(i).pkgList.length; k++)
{
String thisPackage = procInfo.get(i).pkgList[k];
try
{
ai = pm.getApplicationInfo(thisPackage, 0);
}
catch(final NameNotFoundException e)
{
ai = null;
}
if(k > 0) applicationName += " / ";
applicationName += (String)(ai != null ? pm.getApplicationLabel(ai) : "(unknown)");
}
packages.add(process);
hm = new HashMap<String, Object>();
hm.put(COLUMN_PROCESS_NAME, process);
hm.put(COLUMN_PROCESS_PROP, applicationName);
processList.add(hm);
}
}
// optional sorting
Comparator<HashMap<String, Object>> comparator = new Comparator<HashMap<String, Object>>()
{
public int compare(HashMap<String, Object> object1, HashMap<String, Object> object2)
{
return ((String)object1.get(COLUMN_PROCESS_NAME)).compareToIgnoreCase((String)object2.get(COLUMN_PROCESS_NAME));
}
};
Collections.sort(processList, comparator);
packages.clear();
for(HashMap<String, Object> e : processList)
{
packages.add((String)e.get(COLUMN_PROCESS_NAME));
}
}
}
最后是清单。
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.yourpackage"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="18" />
<uses-permission android:name="android.permission.GET_TASKS" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".MonitorActivity"
android:label="@string/app_name"
android:configChanges="orientation|keyboardHidden" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".MonitorService" />
</application>
</manifest>
如您所见，这已经是很多代码了。它是从一个工作应用程序中提取的部分内容，但我根据您的需要进行了快速更改，因此可能存在拼写错误、所有导入都被跳过等。不过，我希望这会有所帮助。
附录：棒棒糖+
注意：最新的 Android 版本打破了上述方法。以下是官方文档对getRunningTasks 方法和其他方法的说明：
从 LOLLIPOP 开始，此方法不再适用于第三方应用程序：引入以文档为中心的最新消息意味着它可以将个人信息泄露给调用者。为了向后兼容，它仍然会返回一小部分数据：至少是调用者自己的任务，可能还有其他一些已知不敏感的任务，例如 home。
我认为这是一种矫枉过正的做法，并且可以以更有选择性和方便的方式完成。更不用说考虑到谷歌的许多带有隐私问题的内置功能，这似乎太戏剧化了。无论如何，我们对此无能为力。
唯一的解决方法是实现 Android 无障碍服务（更多信息 here 和 here）并拦截所有应用程序从那里获得和失去焦点的操作。用户应手动启用该服务！您的应用程序应该以某种方式指导用户这样做。