您的位置：程序门 -> vb ->

vb向c#程序发送消息的问题

[收藏此页] [打印本页]选择字色：背景色：字体：[大][中][小]

vb向c#程序发送消息的问题

发表于：2007-10-24 13:30:43 楼主

我在vb程序中向c#程序发送消息，用sendmessage函数时c#程序可以收到，但改成postmessage时c#程序就收不到
vb发出的消息。vb的代码如下，请大家看看可能是什么原因

'\\ declarations
private declare function postmessagelong lib "user32" alias "postmessagea" （byval hwnd as long, byval wmsg as long, byval wparam as long, lparam as any) as long

private declare sub copymemory lib "kernel32" alias "rtlmovememory" （byref hpvdest as any, byref hpvsource as any, byval cbcopy as long)

private declare function findwindow lib "user32" alias "findwindowa" （byval lpclassname as string, byval lpwindowname as string) as long

private sub command1_click（)
dim sstring as string
dim lhwnd as long
dim cds as copydatastruct

dim buf（255) as byte

sstring = "string to send"
if sstring = "" then exit sub
'
' get the handle of the target application's visible window.
'
lhwnd = findwindow（vbnullstring, cwindow_title)
if lhwnd then
'
' copy the string into a byte array,
' converting it to ascii. assign lpdata
' the address of the byte array.
'
call copymemory（buf（1), byval sstring, lenb（strconv（sstring, vbfromunicode)))
with cds
.dwdata = 3
.cbdata = lenb（strconv（sstring, vbfromunicode)) + 1
.lpdata = varptr（buf（1))
end with
msgbox （cds.cbdata)

'
' send the string.
'
call postmessagelong（lhwnd, wm_copydata, me.hwnd, cds)
end if
end sub

发表于：2007-10-24 13:42:341楼得分:0

将 cds 定义成模块的全局变量。
postmessage 一般要在你的 command1_click（) 事件结束后进行响应，而作为过程级变量，cds 已经释放。

发表于：2007-10-24 16:07:542楼得分:0

postmessage 是向消息队列发送消息所以要有一个接受的事件去响应
sendmessage 是向窗口发送消息所以不用

发表于：2007-10-25 17:06:033楼得分:0

no
区别在于 sendmessage 是马上响应消息，发送者必须等待消息处理结束；postmessage 是将消息加入队列稍后处理，发送者的过程不会中断。
fudy 的问题在于稍后处理时所需要的 cds 已经被释放，lhwnd 的消息处理过程无法得到正确的参数数据。

发表于：2007-10-25 18:51:204楼得分:0

tiger_zhao回答的非常之正确

发表于：2007-10-27 20:53:035楼得分:0

楼主要是好好看看msdn，估计就不会问这个问题了，下面内容是我从vs 2002 msdn中粘过来的：

wm_copydata
an application sends the wm_copydata message to pass data to another application.

to send this message, call the sendmessage function with the following parameters （do not call the postmessage function).

sendmessage（
（hwnd) hwnd, // handle to destination window
wm_copydata, // message to send
（wparam) wparam, // handle to window （hwnd)
（lparam) lparam // data （pcopydatastruct)
);
parameters
wparam
handle to the window passing the data.
lparam
pointer to a copydatastruct structure that contains the data to be passed.
return values
if the receiving application processes this message, it should return true; otherwise, it should return false.

remarks
the data being passed must not contain pointers or other references to objects not accessible to the application receiving the data.

while this message is being sent, the referenced data must not be changed by another thread of the sending process.

the receiving application should consider the data read-only. the lparam parameter is valid only during the processing of the message. the receiving application should not free the memory referenced by lparam. if the receiving application must access the data after sendmessage returns, it must copy the data into a local buffer.

example code
for an example, see using data copy.

requirements
windows nt/2000/xp: included in windows nt 3.1 and later.
windows 95/98/me: included in windows 95 and later.
header: declared in winuser.h; include windows.h.

see also
sendmessage, copydatastruct

下一篇：回答一些关于tabpages打开/关闭or显示/隐藏的问题
上一篇：vb如何设置excel当前页码和总页码？谢谢：）

其他资讯