我想知道Context.bindService()什么时候返回false？
我试图让onBind()返回null,但是当调用bindService并且onServiceConnected没有执行时它仍然返回true.我也在Google网上论坛上看到了此消息,但没有回复
https://groups.google.com/forum/#!topic/android-developers/ZLl56Mz1jYg
我也找不到bindService的实现,因为它在Context.java中是抽象的,并且搜索“public boolean bindService”也不会产生任何有用的结果(最接近的是ApplicationContext,它似乎不存在于当前的API级别中).
解决方法
binderService的实现是在
android.app.ConntextImpl：
1412 public boolean bindService(Intent service,ServiceConnection conn,int flags,int userHandle) {
1413 IServiceConnection sd;
1414 if (conn == null) {
1415 throw new IllegalArgumentException("connection is null");
1416 }
1417 if (mPackageInfo != null) {
1418 sd = mPackageInfo.getServiceDispatcher(conn,getOuterContext(),1419 mMainThread.getHandler(),flags);
1420 } else {
1421 throw new RuntimeException("Not supported in system context");
1422 }
1423 try {
1424 IBinder token = getActivityToken();
1425 if (token == null && (flags&BIND_AUTO_CREATE) == 0 && mPackageInfo != null
1426 && mPackageInfo.getApplicationInfo().targetSdkVersion
1427 < android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
1428 flags |= BIND_WAIVE_PRIORITY;
1429 }
1430 service.setAllowFds(false);
1431 int res = ActivityManagerNative.getDefault().bindService(
1432 mMainThread.getApplicationThread(),getActivityToken(),1433 service,service.resolveTypeIfNeeded(getContentResolver()),1434 sd,flags,userHandle);
1435 if (res < 0) {
1436 throw new SecurityException(
1437 "Not allowed to bind to service " + service);
1438 }
1439 return res != 0;
1440 } catch (RemoteException e) {
1441 return false;
1442 }
1443 }
从第1431行开始,您可以看到它调用ActivityManagerNative的bindService.
该实施是在com.android.server.am.ActivityManagerService：
11070 public int bindService(IApplicationThread caller,IBinder token,11071 Intent service,String resolvedType,11072 IServiceConnection connection,int userId) {
11073 enforceNotIsolatedCaller("bindService");
11074 // Refuse possible leaked file descriptors
11075 if (service != null && service.hasFileDescriptors() == true) {
11076 throw new IllegalArgumentException("File descriptors passed in Intent");
11077 }
11078
11079 synchronized(this) {
11080 return mServices.bindServiceLocked(caller,token,service,resolvedType,11081 connection,userId);
11082 }
11083 }
所以它最终调用了bindeServiceLocked为com.android.server.am.ActiveServices.
更新：
通过读取binderServiceLocked()的代码：
472 ServiceLookupResult res =
473 retrieveServiceLocked(service,474 Binder.getCallingPid(),Binder.getCallingUid(),userId,true);
475 if (res == null) {
476 return 0;
477 }
478 if (res.record == null) {
479 return -1;
480 }
发现如果retrieveServiceLocked()的结果为null,则返回false.
检查retrieveServiceLocked()的代码后
721 ResolveInfo rInfo =
722 AppGlobals.getPackageManager().resolveService(
723 service,724 ActivityManagerService.STOCK_PM_FLAGS,userId);
725 ServiceInfo sInfo =
726 rInfo != null ? rInfo.serviceInfo : null;
727 if (sInfo == null) {
728 Slog.w(TAG,"Unable to start service " + service + " U=" + userId +
729 ": not found");
730 return null;
731 }
发现如果无法获取Service的ResolveInfo,则会出错.
所以我尝试删除AndroidManifest.xml中的Service声明,发现bindService()返回false.