Golang通过syscall调用windows dll方法

本用例在GO 1.4.2 上编译执行通过，直接上CODE：

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))
}

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下的另一种DLL方法调用", "HELLO !")
time.Sleep(3 * time.Second)
}

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

运行效果：





---

syscall延伸阅读：

golang的OLE调用工具包

https://github.com/mattn/go-ole

---

以下介绍来源：http://wendal.net/2013/0406.html

syscall.Syscall系列方法

当前共5个方法

syscall.Syscallsyscall.Syscall6syscall.Syscall9syscall.Syscall12syscall.Syscall15

分别对应 3个/6个/9个/12个/15个参数或以下的调用

参数都形如

syscall.Syscall(trap, nargs, a1, a2, a3)

第二个参数, nargs 即参数的个数,一旦传错, 轻则调用失败,重者直接APPCARSH

多余的参数, 用0代替

调用示例

获取磁盘空间

//首先,准备输入参数, GetDiskFreeSpaceEx需要4个参数, 可查MSDNdir := "C:"lpFreeBytesAvailable := int64(0)
//注意类型需要跟API的类型相符lpTotalNumberOfBytes := int64(0)lpTotalNumberOfFreeBytes := int64(0)
//获取方法的引用kernel32, err := syscall.LoadLibrary("Kernel32.dll")
// 严格来说需要加上 defer syscall.FreeLibrary(kernel32)
// GetDiskFreeSpaceEx, err := syscall.GetProcAddress(syscall.Handle(kernel32), "GetDiskFreeSpaceExW")
//执行之. 因为有4个参数,故取Syscall6才能放得下. 最后2个参数,自然就是0了r, _, errno := syscall.Syscall6(uintptr(GetDiskFreeSpaceEx), 4,
uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("C:"))),
uintptr(unsafe.Pointer(&lpFreeBytesAvailable)),
uintptr(unsafe.Pointer(&lpTotalNumberOfBytes)),
uintptr(unsafe.Pointer(&lpTotalNumberOfFreeBytes)), 0, 0)
// 注意, errno并非error接口的, 不可能是nil// 而且,根据MSDN的说明,返回值为0就fail, 不为0就是成功if r != 0 {
log.Printf("Free %dmb", lpTotalNumberOfFreeBytes/1024/1024)}

简单点的方式? 用syscall.Call

跟Syscall系列一样, Call方法最多15个参数. 这里用来Must开头的方法, 如不存在,会panic.

    h := syscall.MustLoadDLL("kernel32.dll")
c := h.MustFindProc("GetDiskFreeSpaceExW")
lpFreeBytesAvailable := int64(0)
lpTotalNumberOfBytes := int64(0)
lpTotalNumberOfFreeBytes := int64(0)
r2, _, err := c.Call(uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("F:"))),
uintptr(unsafe.Pointer(&lpFreeBytesAvailable)),
uintptr(unsafe.Pointer(&lpTotalNumberOfBytes)),
uintptr(unsafe.Pointer(&lpTotalNumberOfFreeBytes)))
if r2 != 0 {
log.Println(r2, err, lpFreeBytesAvailable/1024/1024)