在Windows平台上有能需要调用一部分Windows API实现高效率的功能实现。下面是一个例子，演示通过调用shell32.dll中ShellExecute函数执行安装的WinRAR程序。
函数原型如下：
HINSTANCE ShellExecute(
_In_opt_ HWND hwnd,
_In_opt_ LPCTSTR lpOperation,
_In_ LPCTSTR lpFile,
_In_opt_ LPCTSTR lpParameters,
_In_opt_ LPCTSTR lpDirectory,
_In_ INT nShowCmd
);
实现代码如下：
package main
import "syscall"
import "unsafe"
func main() {
var hand uintptr = uintptr(0);
var operator uintptr = uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("open")));
var fpath uintptr = uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr("C:\\Program Files\\WinRAR\\WinRAR.exe")));
var param uintptr = uintptr(0);
var dirpath uintptr = uintptr(0);
var ncmd uintptr = uintptr(1);
shell32 := syscall.NewLazyDLL("shell32.dll");
ShellExecuteW := shell32.NewProc("ShellExecuteW");
_,_,_ = ShellExecuteW.Call(hand,operator,fpath,param,dirpath,ncmd);
}
然后完善下ShellExecute函数：
func ShellExecute(hwnd HWND, lpOperation, lpFile, lpParameters, lpDirectory string, nShowCmd int) error {
var op, param, directory uintptr
if len(lpOperation) != 0 {
op = uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpOperation)))
}
if len(lpParameters) != 0 {
param = uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpParameters)))
}
if len(lpDirectory) != 0 {
directory = uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpDirectory)))
}
ret, _, _ := procShellExecute.Call(
uintptr(hwnd),
op,
uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(lpFile))),
param,
directory,
uintptr(nShowCmd))
errorMsg := ""
if ret != 0 && ret <= 32 {
switch int(ret) {
case ERROR_FILE_NOT_FOUND:
errorMsg = "The specified file was not found."
case ERROR_PATH_NOT_FOUND:
errorMsg = "The specified path was not found."
case ERROR_BAD_FORMAT:
errorMsg = "The .exe file is invalid (non-Win32 .exe or error in .exe image)."
case SE_ERR_ACCESSDENIED:
errorMsg = "The operating system denied access to the specified file."
case SE_ERR_ASSOCINCOMPLETE:
errorMsg = "The file name association is incomplete or invalid."
case SE_ERR_DDEBUSY:
errorMsg = "The DDE transaction could not be completed because other DDE transactions were being processed."
case SE_ERR_DDEFAIL:
errorMsg = "The DDE transaction failed."
case SE_ERR_DDETIMEOUT:
errorMsg = "The DDE transaction could not be completed because the request timed out."
case SE_ERR_DLLNOTFOUND:
errorMsg = "The specified DLL was not found."
case SE_ERR_NOASSOC:
errorMsg = "There is no application associated with the given file name extension. This error will also be returned if you attempt to print a file that is not printable."
case SE_ERR_OOM:
errorMsg = "There was not enough memory to complete the operation."
case SE_ERR_SHARE:
errorMsg = "A sharing violation occurred."
default:
errorMsg = fmt.Sprintf("Unknown error occurred with error code %v", ret)
}
} else {
return nil
}
return errors.New(errorMsg)
}