Golang调用windows下的dll动态库中的函数

Golang调用windows下的dll动态库中的函数
使用syscall调用。

package main

import (
    "fmt"
    "syscall"
    "time"
    "unsafe"
)

const (
    MB_OK                = 0x00000000
    MB_OKCANCEL          = 0x00000001
    MB_ABORTRETRYIGnorE  = 0x00000002
    MB_YESNOCANCEL       = 0x00000003
    MB_YESNO             = 0x00000004
    MB_RETRYCANCEL       = 0x00000005
    MB_CANCELTRYCONTINUE = 0x00000006
    MB_ICONHAND          = 0x00000010
    MB_ICONQUESTION      = 0x00000020
    MB_ICONEXCLAMATION   = 0x00000030
    MB_ICONASTERISK      = 0x00000040
    MB_USERICON          = 0x00000080
    MB_ICONWARNING       = MB_ICONEXCLAMATION
    MB_ICONERROR         = MB_ICONHAND
    MB_ICONinformatION   = MB_ICONASTERISK
    MB_ICONSTOP          = MB_ICONHAND

    MB_DEFBUTTON1 = 0x00000000
    MB_DEFBUTTON2 = 0x00000100
    MB_DEFBUTTON3 = 0x00000200
    MB_DEFBUTTON4 = 0x00000300
)

func abort(funcname string,err syscall.Errno) {
    panic(funcname + " Failed: " + err.Error())
}

var (
    // kernel32,_ = syscall.LoadLibrary("kernel32.dll")
    // getModuleHandle,_ = syscall.GetProcAddress(kernel32,"GetModuleHandleW")

    user32,_     = syscall.LoadLibrary("user32.dll")
    messageBox,_ = syscall.GetProcAddress(user32,"MessageBoxW")
)

func IntPtr(n int) uintptr {
    return uintptr(n)
}

func StrPtr(s string) uintptr {
    return uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(s)))
}

func MessageBox(caption,text string,style uintptr) (result int) {
    ret,_,callErr := syscall.Syscall9(messageBox, 4, 0,StrPtr(text),StrPtr(caption),style, 0)
    if callErr != 0 {
        abort("Call MessageBox",callErr)
    }
    result = int(ret)
    return
}

//func GetModuleHandle() (handle uintptr) {
// if ret,callErr := syscall.Syscall(getModuleHandle,0); callErr != 0 {
// abort("Call GetModuleHandle",callErr)
// } else {
// handle = ret
// }
// return
//}

// windows下的第二种DLL方法调用
func ShowMessage2(title,text string) {
    user32 := syscall.NewLazyDLL("user32.dll")
    MessageBoxW := user32.NewProc("MessageBoxW")
    MessageBoxW.Call(IntPtr(0),StrPtr(title),IntPtr(0))
}

func main() {
    // defer syscall.FreeLibrary(kernel32)
    defer syscall.FreeLibrary(user32)

    //fmt.Printf("Retern: %d\n",MessageBox("Done Title","This test is Done.",MB_YESNOCANCEL))
    num := MessageBox("Done Title","This test is Done.",MB_YESNOCANCEL)
    fmt.Printf("Get Retrun Value Before MessageBox Invoked: %d\n",num)
    ShowMessage2("windows下的第二种DLL方法调用","HELLO !")
    time.Sleep(3 * time.Second)
}

func init() {
    fmt.Print("Starting Up\n")
}