go 调用windows dll 的方法

go 调用windows dll 的方法 ，代码如下：

 

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, 0, 0, 0, 0)
	if callerr != 0 {
		abort("call messagebox", callerr)
	}
	result = int(ret)
	return
}

//func getmodulehandle() (handle uintptr) {
//    if ret, _, callerr := syscall.syscall(getmodulehandle, 0, 0, 0, 0); callerr != 0 {
//        abort("call getmodulehandle", callerr)
//    } else {
//        handle = ret
//    }
//    return
//}

// windows下的另一种dll方法调用
func showmessage2(title, text string) {
	user32 := syscall.newlazydll("user32.dll")
	messageboxw := user32.newproc("messageboxw")
	messageboxw.call(intptr(0), strptr(text), strptr(title), intptr(0))
}

// windows下的第三种dll方法调用
func showmessage3(title, text string) {
	user32,_ := syscall.loaddll("user32.dll")
	messageboxw,_ := user32.findproc("messageboxw")
	messageboxw.call(intptr(0), strptr(text), strptr(title), intptr(0))
}

func main() {
	//    defer syscall.freelibrary(kernel32)
	defer syscall.freelibrary(user32) //释放指定的动态链接库

	showmessage2("windows下的另一种dll方法调用", "hello !")

	showmessage3("windows下的第三种dll方法调用", "hello3 !")

	//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)

	time.sleep(3 * time.second)
}

func init() {
	fmt.print("starting up\n")
}