| 发表于：2007-06-06 20:30:193楼 得分:0 |
imports system.runtime.interopservices
namespace my
partial class mycomputer
public function structtobytes（byval structobj as object) as byte（)
dim size as integer = marshal.sizeof（structobj)
dim buffer as intptr = marshal.allochglobal（size)
try
marshal.structuretoptr（structobj, buffer, false)
dim bytes as byte（) = new byte（size - 1) {}
marshal.copy（buffer, bytes, 0, size)
return bytes
finally
marshal.freehglobal（buffer)
end try
end function
public function bytestostruct（byval bytes as byte（), byval strcuttype as type) as object
dim size as integer = marshal.sizeof（strcuttype)
dim buffer as intptr = marshal.allochglobal（size)
try
marshal.copy（bytes, 0, buffer, size)
return marshal.ptrtostructure（buffer, strcuttype)
finally
marshal.freehglobal（buffer)
end try
end function
end class
end namespace
imports system.text
imports system.net
imports system.net.sockets
imports system.threading
public class server
private sendbuf as byte（)
private receivebuf as byte（)
private iserver as udpclient
private tserver as thread
private tserverjoin as thread
private groupep as ipendpoint
private remoteep as ipendpoint
private sendinfo as sendstruc
public event receivemessage as system.eventhandler
public sub broadcast（byval sendtype as string, byval imessage as string)
sendinfo.command = sendtype
sendinfo.value = imessage
sendbuf = my.computer.structtobytes（sendinfo)
iserver.send（sendbuf, sendbuf.length, groupep)
end sub
public sub new（)
groupep = new ipendpoint（ipaddress.parse（ "239.1.1.3 "), 10000)
iserver = new udpclient（groupep.port)
iserver.joinmulticastgroup（groupep.address)
tserver = new thread（addressof serverlistener)
tserver.start（)
tserverjoin = new thread（addressof waitingforlistener)
tserverjoin.start（)
end sub
private sub serverlistener（)
dim receiveinfo as new sendstruc（true)
dim receivemessage as string = " "
do
try
receivebuf = iserver.receive（remoteep)
receiveinfo = my.computer.bytestostruct（receivebuf, receiveinfo.gettype)
if receiveinfo.value = " " then receiveinfo.value = "（空消息) "
if receiveinfo.command = "joinserver " then
receivemessage = receiveinfo.value
tserverjoin.abort（)
elseif receiveinfo.command = "send " then
receivemessage = "收到来自 " & remoteep.tostring & "的信息： " & receiveinfo.value
end if
raiseevent receivemessage（receivemessage, new system.eventargs)
catch ex as exception
end try
loop
end sub
private sub waitingforlistener（)
thread.sleep（100)
broadcast（ "joinserver ", getlocalip（) & ": " & groupep.port & "加入组播！ ")
end sub
public sub close（)
broadcast（ "joinserver ", getlocalip（) & ": " & groupep.port & "退出组播！ ")
iserver.dropmulticastgroup（groupep.address)
iserver.close（)
tserver.abort（)
end sub
private function getlocalip（) as string
dim addr as system.net.ipaddress
addr = system.net.dns.gethostaddresses（system.net.dns.gethostname（))（0)
return addr.tostring
end function
private structure sendstruc
public sub new（byval initme as boolean)
if initme then
command = " "
value = " "
end if
end sub
public command as string
public value as string
end structure
end class
public class form1
private withevents myserver as new server
private delegate sub invokedelegate（)
private receivemessage as string
private sub form1_formclosing（byval sender as object, byval e as system.windows.forms.formclosingeventargs) handles me.formclosing
myserver.close（)
end sub
private sub button1_click（byval sender as system.object, byval e as system.eventargs) handles button1.click
myserver.broadcast（ "send ", textbox1.text)
end sub
private sub receive（byval sender as system.object, byval e as system.eventargs) handles myserver.receivemessage
receivemessage = sender.tostring
textbox2.begininvoke（new invokedelegate（addressof receiveinvoke))
end sub
private sub receiveinvoke（)
textbox2.appendtext（receivemessage & vbcrlf)
end sub
end class
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