怎样用C#调用comdlg32.dll，利用GetOpenFileName实现打开文件对话框，最好有源码。

Question

我知道C#可以引用System.Windows.Forms，不过我想实现用C#单纯调用Windows API实现打开文件对话框功能，希望高手指点，给我源码啊。我的QQ：474186854
[DllImport("dll文件名")]
public static extern 返回值 函数名（参数） 这种方法我知道，不过对于Win API的comdlg32.dll 中的 GetOpenFileName方法，他的参数是 C定义的一个Struct结构，我不知道在 C#中如何实现。希望能有完整源码，一定加分。

Answer 1

// Copyright
// Microsoft Corporation
// All rights reserved

// OpenFileDlg.cs

using System;
using System.Text;
using System.Runtime.InteropServices;

/*
typedef struct tagOFN {
DWORD lStructSize;
HWND hwndOwner;
HINSTANCE hInstance;
LPCTSTR lpstrFilter;
LPTSTR lpstrCustomFilter;
DWORD nMaxCustFilter;
DWORD nFilterIndex;
LPTSTR lpstrFile;
DWORD nMaxFile;
LPTSTR lpstrFileTitle;
DWORD nMaxFileTitle;
LPCTSTR lpstrInitialDir;
LPCTSTR lpstrTitle;
DWORD Flags;
WORD nFileOffset;
WORD nFileExtension;
LPCTSTR lpstrDefExt;
LPARAM lCustData;
LPOFNHOOKPROC lpfnHook;
LPCTSTR lpTemplateName;
#if (_WIN32_WINNT >= 0x0500)
void * pvReserved;
DWORD dwReserved;
DWORD FlagsEx;
#endif // (_WIN32_WINNT >= 0x0500)
} OPENFILENAME, *LPOPENFILENAME;
*/

[ StructLayout( LayoutKind.Sequential, CharSet=CharSet.Auto )]
public class OpenFileName
{
public int structSize = 0;
public IntPtr dlgOwner = IntPtr.Zero;
public IntPtr instance = IntPtr.Zero;

public String filter = null;
public String customFilter = null;
public int maxCustFilter = 0;
public int filterIndex = 0;

public String file = null;
public int maxFile = 0;

public String fileTitle = null;
public int maxFileTitle = 0;

public String initialDir = null;

public String title = null;

public int flags = 0;
public short fileOffset = 0;
public short fileExtension = 0;

public String defExt = null;

public IntPtr custData = IntPtr.Zero;
public IntPtr hook = IntPtr.Zero;

public String templateName = null;

public IntPtr reservedPtr = IntPtr.Zero;
public int reservedInt = 0;
public int flagsEx = 0;
}

public class LibWrap
{
//BOOL GetOpenFileName(LPOPENFILENAME lpofn);

[ DllImport( "Comdlg32.dll", CharSet=CharSet.Auto )]
public static extern bool GetOpenFileName([ In, Out ] OpenFileName ofn );
}

public class App
{
public static void Main()
{
OpenFileName ofn = new OpenFileName();

ofn.structSize = Marshal.SizeOf( ofn );

ofn.filter = "Log files\0*.log\0Batch files\0*.bat\0";

ofn.file = new String( new char[ 256 ]);
ofn.maxFile = ofn.file.Length;

ofn.fileTitle = new String( new char[ 64 ]);
ofn.maxFileTitle = ofn.fileTitle.Length;

ofn.initialDir = "C:\\";
ofn.title = "Open file called using platform invoke...";
ofn.defExt = "txt";

if( LibWrap.GetOpenFileName( ofn ))
{
Console.WriteLine( "Selected file with full path: {0}", ofn.file );
Console.WriteLine( "Selected file name: {0}", ofn.fileTitle );
Console.WriteLine( "Offset from file name: {0}", ofn.fileOffset );
Console.WriteLine( "Offset from file extension: {0}", ofn.fileExtension );
}
}
}

Answer 2

..用API就不要用c#了c++吧

可以采用P/Invoke方法，这是一种C#与win32 API互操作的方法，用法如下
[DllImport("winmm.dll")]
public static extern int waveOutGetVolume(IntPtr hwo, out uint dwVolume);
DllImport用于指定API所在的dll，之后用extern关键字声明一个在C#中和API等价的签名，然后在类型中就可以使用了，如果不清楚C#中与你想用的API等价的方法签名，可以查下百度。

Answer 3

这个结构体是这样的:
下面是VB代码，
VB定义Struct的格式是：
Type 结构体名
变量 as 类型
…………
End Type
Integer就是C#里面的int32
结构就是这么个结构。
Public Type OPENFILENAME
lStructSize As Long
hwndOwner As Long
hInstance As Long
lpstrFilter As String
lpstrCustomFilter As String
nMaxCustFilter As Long
nFilterIndex As Long
lpstrFile As String
nMaxFile As Long
lpstrFileTitle As String
nMaxFileTitle As Long
lpstrInitialDir As String
lpstrTitle As String
flags As Long
nFileOffset As Integer
nFileExtension As Integer
lpstrDefExt As String
lCustData As Long
lpfnHook As Long
lpTemplateName As String
End Type

============================
使用时是这样的：不好意思还是VB代码

Dim OpenFile As OPENFILENAME
Dim lReturn As Long
Dim sFilter As String

On Error GoTo HandleErr

OpenFile.lStructSize = Len(OpenFile)
OpenFile.hwndOwner = Me.Hwnd
sFilter = "Textdateien (*.txt)" & Chr(0) & "*.txt" & Chr(0)
OpenFile.lpstrFilter = sFilter
OpenFile.nFilterIndex
OpenFile.lpstrFile = String(257, 0)
OpenFile.nMaxFile = Len(OpenFile.lpstrFile) - 1
OpenFile.lpstrFileTitle = OpenFile.lpstrFile
OpenFile.nMaxFileTitle = OpenFile.nMaxFile
OpenFile.lpstrInitialDir = "C:\"
OpenFile.lpstrTitle = "'Öffnen'-Dialog der Common Dialog API"
OpenFile.flags = 0
lReturn = GetOpenFileName(OpenFile)
If lReturn = 0 Then
MsgBox "Der Anwender hat die Aktion abgebrochen."
Else
MsgBox "Der Anwender hat den folgenden Pfad und Datei angegeben: " _
& Trim(OpenFile.lpstrFile)
End If

Answer 4

那就用api啊，c#调用API和C类似，你可以百度下