SendMessage返回1400错误（无效的窗口句柄）

Question

进程A和B都需要向进程C通过WM_COPYDATA发送消息，C的句柄HWND在启动时存储于数据中以供A和B获取。

A和B发送消息方法如下

LRESULT result = ::SendMessage(hProxyWnd, WM_COPYDATA, (WPARAM) 0, (LPARAM) &strctToPass);

但是A能够顺利将信息发送到C，但是B却不能，通过WSAGetLastError ()发现返回的都是1400错误代码，即无效的窗口句柄，但是B的句柄和A获取的是一模一样的，为何A能发送成功而B不能？

这个问题比较挠头，大家有没有比较好的思路来调试/解决这个问题。

不胜感激！

Answer 1

HWND只在当前session有效。检查你的进程是否在同一个桌面。

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Answer 2

是在同一个桌面的，Spy++可以看到，只是没有title罢了

Answer 3

用GetLastError看看，WSAGetLastError 是socket的，和你的问题没关系

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Answer 4

恩，谢谢。还是1400.

 

补充一下， 进程A和B的区别在于

A被部署为DLL于MSSQL\Binn, SQL Server通过扩展存储过程调用了A中的API，而B是被注册为Windows服务。

Answer 5

服务和桌面程序不是在一个桌面上，你不能在桌面程序和服务程序之间共享窗口句柄。用RPC、Socket、命名管道之类可以跨session的通讯方式吧。

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Answer 6

如果服务设置了“Allow service to interact with desktop”-- 允许与桌面交互，那么桌面应用程序是否可以和服务共享窗口句柄？

谢谢！

Answer 7

可能可以，取决于桌面应用程序的session是不是和服务的session一致。

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Answer 8

最好还是用跨进程的方式来收发数据吧，用CreatePipe建立实名管道通信，这样比较简单

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0xBAADF00D

Answer 9

关于您的是否同一个session的问题，我找到一篇文章

http://blog.csdn.net/qinlicang/archive/2009/07/17/4356662.aspx

我是同一个用户登录系统启动服务运行程序，这两者应该是同一个session吧？

谢谢！

Answer 10

嗯，如果是第一个从物理终端登录的用户的话，是的

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Answer 11

很谢谢Vonger和Sheng Jiang的建议。

采用其他的方法是可以实现进程间通信，但是既然同一个物理终端，服务又允许和桌面交互，为何应用程序无法向服务发送信息，返回无效句柄的错误，有点挠头，但是还想找出最终的答案。

谢谢！

Answer 12

HWND只在当前session有效。同一个用户可以登录多个session。

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Answer 13

请教如何查看windows中的session？如何判断服务的应用程序各自所在的session？

谢谢！

Answer 14

任务管理器里面可以看到，sessionID列默认不显示，需要手动添加

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Answer 15

恩是的

服务的session ID是0，而应用程序的1，怪不得不能共享句柄