我必须跟踪编辑特定文本字段的时间，而不管设备时间（用户可以更改）以及他没有连接到互联网。 因此，我尝试在服务中运行的计时器启动活动时启动服务。当用户更改文本字段时，我可以在计时器值的帮助下获得正确的时间。 所以我在创建服务方面非常成功，在服务和活动之间进行双向沟通。 我在这里遇到的唯一一个大问题是，当我在杀戮后重新启动活动时，我无法将计数器变量的值恢复到我离开它之前杀死活动的位置。
服务：
public class CounterService extends Service {
/** Keeps track of all current registered clients. */
ArrayList<Messenger> mClients = new ArrayList<Messenger>();
static final int MSG_REGISTER_CLIENT = 1;
static final int MSG_UNREGISTER_CLIENT = 2;
static final int MSG_SET_VALUE = 3;
static final int MSG_GET_COUNT = 4;
/**
* Target we publish for clients to send messages to IncomingHandler.
*/
final Messenger mMessenger = new Messenger(new IncomingHandler());
private static Timer timer;
private HashMap<Integer, Integer> countMissionId = new HashMap<Integer, Integer>();
/**
* Class used for the client Binder. Because we know this service always
* runs in the same process as its clients, we don't need to deal with IPC.
*/
public class LocalBinder extends Binder {
}
@Override
public void onCreate() {
super.onCreate();
// setCount(0);
}
private void startTimerService() {
if (timer == null) {
timer = new Timer();
}
timer.scheduleAtFixedRate(new mainTask(), 0, 1000);
}
private void endTimerService() {
if (timer != null)
timer.cancel();
}
private class mainTask extends TimerTask {
public void run() {
for (Entry<Integer, Integer> entry : countMissionId.entrySet()) {
entry.setValue(entry.getValue() + 1);
Log.d("sg",
"Count:" + entry.getValue() + "Mission Id"
+ entry.getKey());
}
}
}
@Override
public IBinder onBind(Intent intent) {
return mMessenger.getBinder();
}
public void sendMessageActivity(int mission_id, int service_type) {
try {
if (mMessenger != null) {
Message msg = Message
.obtain(null, service_type, mission_id, -1);
msg.replyTo = mMessenger;
mMessenger.send(msg);
}
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
}
}
class IncomingHandler extends Handler {
private int mValue;
@Override
public void handleMessage(Message msg) {
int missionId = msg.arg1;
switch (msg.what) {
case MSG_REGISTER_CLIENT:
countMissionId.put(missionId, 0);
break;
case MSG_UNREGISTER_CLIENT:
countMissionId.remove(missionId);
if (countMissionId.size() == 0) {
stopSelf();
}
break;
case MSG_SET_VALUE:
// endTimerService();
startTimerService();
break;
case MSG_GET_COUNT:
Log4Android.l(this, "In service" + countMissionId.get(missionId));
sendMessageActivity(missionId, -1);
case 6:
mClients.add(msg.replyTo);
break;
case 7:
mClients.remove(msg.replyTo);
break;
case 8:
mValue = msg.arg1;
for (int i = mClients.size() - 1; i >= 0; i--) {
try {
mClients.get(i).send(
Message.obtain(null, MSG_SET_VALUE, mValue, 0));
} catch (RemoteException e) {
// The client is dead. Remove it from the list;
// we are going through the list from back to front
// so this is safe to do inside the loop.
mClients.remove(i);
}
}
default:
super.handleMessage(msg);
}
}
}
}
的活动：
class IncomingHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case -1:
Log.d("sg","almost there volla vollla");
default:
super.handleMessage(msg);
}
}
}
/**
* Target we publish for clients to send messages to IncomingHandler.
*/
final Messenger mMessenger = new Messenger(new IncomingHandler());
/** Messenger for communicating with service. */
Messenger mService = null;
/** Flag indicating whether we have called bind on the service. */
boolean mIsBound;
/** Some text view we are using to show state information. */
private ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className,
IBinder service) {
// This is called when the connection with the service has been
// established, giving us the service object we can use to
// interact with the service. We are communicating with our
// service through an IDL interface, so get a client-side
// representation of that from the raw service object.
mService = new Messenger(service);
try {
Message msg = Message.obtain(null,
6);
msg.replyTo = mMessenger;
mService.send(msg);
// Give it some value as an example.
msg = Message.obtain(null,
8, this.hashCode(), 0);
mService.send(msg);
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
}
// We want to monitor the service for as long as we are
// connected to it.
// As part of the sample, tell the user what happened.
Toast.makeText(getApplicationContext(), "Volla",
Toast.LENGTH_SHORT).show();
}
public void onServiceDisconnected(ComponentName className) {
// This is called when the connection with the service has been
// unexpectedly disconnected -- that is, its process crashed.
mService = null;
// As part of the sample, tell the user what happened.
Toast.makeText(getApplicationContext(), "Volla Disconnected",
Toast.LENGTH_SHORT).show(); }
};
private Intent counterService;
void doBindService() {
// Establish a connection with the service. We use an explicit
// class name because there is no reason to be able to let other
// applications replace our component.
counterService =new Intent(MainActivity.this,CounterService.class);
startService(counterService);
bindService(counterService, mConnection, application.BIND_AUTO_CREATE);
mIsBound = true;
}
void doUnbindService() {
if (mIsBound) {
// If we have received the service, and hence registered with
// it, then now is the time to unregister.
if (mService != null) {
try {
Message msg = Message.obtain(null,
8);
msg.replyTo = mMessenger;
mService.send(msg);
} catch (RemoteException e) {
// There is nothing special we need to do if the service
// has crashed.
}
}
// Detach our existing connection.
unbindService(mConnection);
mIsBound = false;
}
}
public void sendMessage(int mission_id,int service_type){
try {
if(mService!=null){
Message msg = Message.obtain(null,
service_type,mission_id,-1);
msg.replyTo = mMessenger;
mService.send(msg);
}
} catch (RemoteException e) {
// In this case the service has crashed before we could even
// do anything with it; we can count on soon being
// disconnected (and then reconnected if it can be restarted)
// so there is no need to do anything here.
}
}
答案 0 :(得分：1)
在Android中，如果需要在活动重新启动时保持值，则需要将值存储在文件，首选项或数据库中。然后，您可以在Activity重新启动时加载该值。
以下是有关保存数据的文档：http://developer.android.com/training/basics/data-storage/index.html