ServiceConnection.onServiceConnected（）绑定到开始服务之后，从来没有所谓的 [英] ServiceConnection.onServiceConnected() never called after binding to started service
问题描述
在游戏应用我有以下情形：
- 从主游戏
活动，播放器开始，在与时间长短不一后台运行多个游戏任务。 - 玩家应该能够查看在一个单独的
查看的运行游戏的任务的进度。
要做到这一点，我创建了两个活动和一个服务，定义如下：
-
服务ProgressService处理几个进度S上并行线程同时运行。 -
活动WorkScreen2创建一个游戏任务，启动服务与startService （）在传递任务参数捆绑。 -
活动ProgressScreen绑定到服务来获取和显示进度S的正在运行的任务。 -
在单独运行这两项活动
TabHost取值一个TabActivity。
我遇到的问题是， ServiceConnection.onServiceConnected（）方法不会被调用。我得到一个显示java.lang.NullPointerException ，因为我尝试调用服务对象应在指定的方法此方法。见下面code。
我用 getApplicationContext（）。bindService（）绑定活动到服务，因为 则tabspec 无法绑定到服务 。这个方法返回真。因此，绑定成功
下面是服务：
公共类ProgressService扩展服务实现GameConstants {
公共静态最后弦乐BROADCAST_PROGRESS =com.mycompany.android.mygame.progressbroadcast;
私有静态最后长的更新周期= 500;
私人的IBinder mBinder;
私人名单，其中，进度＆GT; mProgressBarList;
私人列表＆LT;字符串＆GT; mStaffNameList;
私人final类ServiceHandler扩展处理程序{
公共ServiceHandler（活套活套）{
超（活套）;
}
@覆盖
公共无效的handleMessage（信息MSG）{
进度进度=新进度（ProgressService.this）;
mProgressBarList.add（进度）;
束束= msg.getData（）;
字符串staffName = bundle.getString（WorkScreen2.STAFF_NAME）;
mStaffNameList.add（staffName）;
INT taskDurationMillis = bundle.getInt（WorkScreen2.TASK_DURATION）* 1000;
progressBar.setMax（taskDurationMillis / 1000）;
长startTimeMillis = SystemClock.uptimeMillis（）;
长elapsedTimeMillis = SystemClock.uptimeMillis（）
- startTimeMillis;
意向意图=新的意图（）;
intent.setAction（BROADCAST_PROGRESS）;
而（elapsedTimeMillis＆LT; taskDurationMillis）{
尝试 {
视频下载（更新周期）;
}赶上（InterruptedException异常E）{
e.printStackTrace（）;
}
elapsedTimeMillis = SystemClock.uptimeMillis（）
- startTimeMillis;
INT elapsedTimeSeconds =（int）的elapsedTimeMillis / 1000;
progressBar.setProgress（elapsedTimeSeconds）;
sendBroadcast（意向）;
}
progressBar.setVisibility（View.GONE）;
mProgressBarList.remove（进度）;
mStaffNameList.remove（staffName）;
sendBroadcast（意向）;
如果（mProgressBarList.isEmpty（））{
stopSelf（msg.arg1）;
}
}
}
@覆盖
公共无效的onCreate（）{
super.onCreate（）;
mBinder =新ProgressServiceBinder（）;
mProgressBarList =集合
.synchronizedList（新的ArrayList＆其中;进度＆GT;（））;
mStaffNameList = Collections.synchronizedList（新的ArrayList＆其中;字符串＆GT;（））;
}
/ *
*创建每场比赛的任务一个线程在传递的参数
*＆LT; code＆GT;的意图＆LT; / code取代;
* /
@覆盖
公众诠释onStartCommand（意向意图，诠释标志，诠释startId）{
Toast.makeText（这一点，启动服务，Toast.LENGTH_LONG）.show（）;
HandlerThread线程=新HandlerThread（ServiceStartArguments
Process.THREAD_PRIORITY_BACKGROUND）;
thread.start（）;
处理器serviceHandler =新ServiceHandler（thread.getLooper（））;
消息味精= serviceHandler.obtainMessage（）;
msg.arg1 = startId;
msg.setData（intent.getExtras（））;
serviceHandler.sendMessage（MSG）;
返回START_STICKY;
}
@覆盖
公众的IBinder onBind（意向意图）{
返回mBinder;
}
公共类ProgressServiceBinder扩展粘合剂{
ProgressService的getService（）{
返回ProgressService.this;
}
}
公开名单＆LT;进度＆GT; getProgressBarList（）{
返回mProgressBarList;
}
公开名单＆LT;字符串＆GT; getStaffNameList（）{
返回mStaffNameList;
}
@覆盖
公共无效的onDestroy（）{
Toast.makeText（这一点，做服务，Toast.LENGTH_SHORT）.show（）;
}
}
这是活动绑定到它：
公共类ProgressScreen扩展ListActivity {
私人最终字符串变量=ProgressScreen;
私人ProgressScreenAdapter mAdapter;
私人ProgressService mProgressService;
私人名单，其中，进度＆GT; mProgressBarList;
私人列表＆LT;字符串＆GT; mStaffNameList;
@覆盖
公共无效的onCreate（束捆）{
Log.i（TAG，ProgressScreen的OnCreate）;
super.onCreate（包）;
的setContentView（R.layout.progress_screen_layout）;
IntentFilter的过滤器=新的IntentFilter（）;
filter.addAction（ProgressService.BROADCAST_PROGRESS）;
registerReceiver（接收机，过滤器）;
doBindService（）;
mAdapter =新ProgressScreenAdapter（这一点，mStaffNameList，mProgressBarList）;
setListAdapter（mAdapter）; //返回true
/ *
*这是我得到的NullPointerException异常
* mProgressService为null这里
* /
mProgressBarList = mProgressService.getProgressBarList（）;
mStaffNameList = mProgressService.getStaffNameList（）;
}
@覆盖
保护无效onResume（）{
super.onResume（）;
IntentFilter的过滤器=新的IntentFilter（）;
filter.addAction（ProgressService.BROADCAST_PROGRESS）;
registerReceiver（接收机，过滤器）;
}
@覆盖
保护无效的onPause（）{
super.onPause（）;
unregisterReceiver（接收机）;
}
布尔doBindService（）{
。返回getApplicationContext（）bindService（新意图（这一点，ProgressService.class），mConnection，Context.BIND_AUTO_CREATE）;
}
无效doUnbindService（）{
。getApplicationContext（）unbindService（mConnection）;
}
ServiceConnection mConnection =新ServiceConnection（）{
公共无效onServiceConnected（组件名的className，粘合剂的IBinder）{
mProgressService =（（ProgressService.ProgressServiceBinder）粘合剂）.getService（）;
Toast.makeText（ProgressScreen.this，连接到ProgressService，Toast.LENGTH_SHORT）.show（）;
}
公共无效onServiceDisconnected（组件名名）{
mProgressService = NULL;
}
};
私人BroadcastReceiver的接收器=新的BroadcastReceiver（）{
@覆盖
公共无效的onReceive（上下文的背景下，意图意图）{
mAdapter.notifyDataSetChanged（）;
}
};
}
而服务从主活动开始如下：
意向意图=新的意图（WorkScreen2.this，ProgressService.class）;
intent.putExtra（TASK_DURATION，task.getDuration（））;
intent.putExtra（STAFF_NAME，staff.getName（））;
startService（意向）;
在的AndroidManifest.xml 包含
＆LT;服务
机器人：名称=。ProgressService
机器人：标签=@字符串/ progress_service＆GT;
＆LT; /服务＆GT;
ServiceConnection的onServiceConnected（）叫，但没有人可以保证，这将是一个名为之前的onCreate继续执行。因此，这里发生的事情 - 你successfuly绑定到该服务（这就是为什么onBind返回true），但是你不能的完全连接的 - onServiceConnected（）尚未被调用，所以当地的mProgressService对象尚未initalized，所以你得到的NullPointerException异常。
解决方法：
将以下两行：
mProgressBarList = mProgressService.getProgressBarList（）;
mStaffNameList = mProgressService.getStaffNameList（）;
从的onCreate（）来onServiceConnected（）函数（使用服务对象的在它是在onServiceConnected初始化（））。
In a game application I have the following scenario:
- From the main game
Activity, the player starts several game tasks that run in the background with varying duration. - The player should be able to view the progress of the running game tasks in a separate
View.
To do this, I created two Activitys and a Service, defined as follows:
Service ProgressServicehandles severalProgressBars running simultaneously on parallel threads.Activity WorkScreen2creates a game task, starts theServicewithstartService()with task parameters passed in aBundle.Activity ProgressScreenbinds to theServiceto get and display theProgressBars of the running tasks.Both activities run under separate
TabHosts of oneTabActivity.
The problem I'm having is that the ServiceConnection.onServiceConnected() method is never called. I get a Java.lang.NullPointerException because I try to call a method of the Service object that should be assigned in this method. See code below.
I use getApplicationContext().bindService() to bind the Activity to the Service because TabSpec cannot bind to Services. This method returns true. Therefore, binding is successful.
Here is the Service:
public class ProgressService extends Service implements GameConstants {
public static final String BROADCAST_PROGRESS = "com.mycompany.android.mygame.progressbroadcast";
private static final long UPDATE_INTERVAL = 500;
private IBinder mBinder;
private List<ProgressBar> mProgressBarList;
private List<String> mStaffNameList;
private final class ServiceHandler extends Handler {
public ServiceHandler(Looper looper) {
super(looper);
}
@Override
public void handleMessage(Message msg) {
ProgressBar progressBar = new ProgressBar(ProgressService.this);
mProgressBarList.add(progressBar);
Bundle bundle = msg.getData();
String staffName = bundle.getString(WorkScreen2.STAFF_NAME);
mStaffNameList.add(staffName);
int taskDurationMillis = bundle.getInt(WorkScreen2.TASK_DURATION) * 1000;
progressBar.setMax(taskDurationMillis / 1000);
long startTimeMillis = SystemClock.uptimeMillis();
long elapsedTimeMillis = SystemClock.uptimeMillis()
- startTimeMillis;
Intent intent = new Intent();
intent.setAction(BROADCAST_PROGRESS);
while (elapsedTimeMillis < taskDurationMillis) {
try {
Thread.sleep(UPDATE_INTERVAL);
} catch (InterruptedException e) {
e.printStackTrace();
}
elapsedTimeMillis = SystemClock.uptimeMillis()
- startTimeMillis;
int elapsedTimeSeconds = (int) elapsedTimeMillis / 1000;
progressBar.setProgress(elapsedTimeSeconds);
sendBroadcast(intent);
}
progressBar.setVisibility(View.GONE);
mProgressBarList.remove(progressBar);
mStaffNameList.remove(staffName);
sendBroadcast(intent);
if (mProgressBarList.isEmpty()) {
stopSelf(msg.arg1);
}
}
}
@Override
public void onCreate() {
super.onCreate();
mBinder = new ProgressServiceBinder();
mProgressBarList = Collections
.synchronizedList(new ArrayList<ProgressBar>());
mStaffNameList = Collections.synchronizedList(new ArrayList<String>());
}
/*
* Creates a thread for each game task with parameters passed in
* <code>intent</code>
*/
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Toast.makeText(this, "starting service", Toast.LENGTH_LONG).show();
HandlerThread thread = new HandlerThread("ServiceStartArguments",
Process.THREAD_PRIORITY_BACKGROUND);
thread.start();
Handler serviceHandler = new ServiceHandler(thread.getLooper());
Message msg = serviceHandler.obtainMessage();
msg.arg1 = startId;
msg.setData(intent.getExtras());
serviceHandler.sendMessage(msg);
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
public class ProgressServiceBinder extends Binder {
ProgressService getService() {
return ProgressService.this;
}
}
public List<ProgressBar> getProgressBarList() {
return mProgressBarList;
}
public List<String> getStaffNameList() {
return mStaffNameList;
}
@Override
public void onDestroy() {
Toast.makeText(this, "Service done", Toast.LENGTH_SHORT).show();
}
}
And this is the Activity that binds to it:
public class ProgressScreen extends ListActivity {
private final String TAG = "ProgressScreen";
private ProgressScreenAdapter mAdapter;
private ProgressService mProgressService;
private List<ProgressBar> mProgressBarList;
private List<String> mStaffNameList;
@Override
public void onCreate(Bundle bundle) {
Log.i(TAG, "ProgressScreen oncreate");
super.onCreate(bundle);
setContentView(R.layout.progress_screen_layout);
IntentFilter filter = new IntentFilter();
filter.addAction(ProgressService.BROADCAST_PROGRESS);
registerReceiver(receiver, filter);
doBindService();
mAdapter = new ProgressScreenAdapter(this, mStaffNameList, mProgressBarList);
setListAdapter(mAdapter); // Returns true
/*
* This is where I get the NullPointerException
* mProgressService is null here
*/
mProgressBarList = mProgressService.getProgressBarList();
mStaffNameList = mProgressService.getStaffNameList();
}
@Override
protected void onResume() {
super.onResume();
IntentFilter filter = new IntentFilter();
filter.addAction(ProgressService.BROADCAST_PROGRESS);
registerReceiver(receiver, filter);
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(receiver);
}
boolean doBindService() {
return getApplicationContext().bindService(new Intent(this, ProgressService.class), mConnection, Context.BIND_AUTO_CREATE);
}
void doUnbindService() {
getApplicationContext().unbindService(mConnection);
}
ServiceConnection mConnection = new ServiceConnection() {
public void onServiceConnected(ComponentName className, IBinder binder) {
mProgressService = ((ProgressService.ProgressServiceBinder) binder).getService();
Toast.makeText(ProgressScreen.this, "Connected to ProgressService", Toast.LENGTH_SHORT).show();
}
public void onServiceDisconnected(ComponentName name) {
mProgressService = null;
}
};
private BroadcastReceiver receiver = new BroadcastReceiver () {
@Override
public void onReceive(Context context, Intent intent) {
mAdapter.notifyDataSetChanged();
}
};
}
And the Service is started from the main Activity as follows:
Intent intent = new Intent(WorkScreen2.this, ProgressService.class);
intent.putExtra(TASK_DURATION, task.getDuration());
intent.putExtra(STAFF_NAME, staff.getName());
startService(intent);
The AndroidManifest.xml contains
<service
android:name=".ProgressService"
android:label="@string/progress_service">
</service>
ServiceConnection's onServiceConnected() is called, but nobody guarantees that it will be called before onCreate continues execution. So, what happens here - you successfuly bind to the service (that's why onBind returns true), but you're not fully connected - onServiceConnected() has not yet been called, so your local mProgressService object is not yet initalized, and therefore you get the NullPointerException.
Solution:
Move these two lines:
mProgressBarList = mProgressService.getProgressBarList();
mStaffNameList = mProgressService.getStaffNameList();
from onCreate() to onServiceConnected() function (use the service object after it is initialized in onServiceConnected()).
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