问题描述
我想知道Context.bindService()什么时候返回false?
I was wondering when does Context.bindService() return false?
我试图使onBind()返回null，但是当调用bindService并且未执行onServiceConnected时，它仍然返回true.我也在Google网上论坛上看到了此信息，但没有任何回应 https://groups.google.com/forum/#!topic/android -developers/ZLl56Mz1jYg
I've tried to make the onBind() return null, but it still returns true when bindService is called and the onServiceConnected does not get executed. I also saw this on Google Groups with no responsehttps://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(最近的是ApplicationContext，它似乎不存在于当前的API级别.
I also can't find the implementation of bindService, since it is abstract in Context.java and searching for "public boolean bindService" does not yield any useful results either (closest was ApplicationContext which does not seem to be present in the current API levels).
推荐答案
binderService的实现在android.app.ConntextImpl :
The implementation of binderService is in 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1431行开始，您可以看到它调用了ActivityManagerNative的bindService.
此实现位于:
From line 1431, you can see it calls ActivityManagerNative's bindService.
This implementation is in com.android.server.am.ActivityManagerService:
11070 public int bindService(IApplicationThread caller, IBinder token,
11071 Intent service, String resolvedType,
11072 IServiceConnection connection, int flags, 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, flags, userId);
11082 }
11083 }
，因此它最终调用.
更新:
通过阅读binderServiceLocked()的代码:
By reading the code of binderServiceLocked():
472 ServiceLookupResult res =
473 retrieveServiceLocked(service, resolvedType,
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，它将返回false.
S检查完retrieveServiceLocked()的代码后
Found that if result of retrieveServiceLocked() is null, it will return false.
SAfter checking the code of retrieveServiceLocked()
721 ResolveInfo rInfo =
722 AppGlobals.getPackageManager().resolveService(
723 service, resolvedType,
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，它将为false.
Found that If can't get the ResolveInfo of Service, it will false.
因此，我尝试删除 AndroidManifest.xml 中的服务声明，并发现bindService()返回false.
So I tried to remove the Service declaration in AndroidManifest.xml and find that the bindService() return false.
这篇关于在什么情况下，bindService返回false?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！