C# 进程间通信之二传递复杂数据类型(转)

C#下使用WM_COPYDATA传输数据说到Marshal的应用

笔者曾在一个项目的实施过程中,需要使用WM_COPYDATA在本地机器的两个进程间传输数据。在C++中实现非常简单,但在C#中实现时却出现了麻烦。由于没有指针,使用COPYDATASTRUCT结构传递数据时,无法正确传递lpData。从网上搜寻文档,找到一个例子,是将COPYDATASTRUCT结构的lpData声明为string。这样虽然能传递字符串,但不能传递随意的二进制数据。

偶然地,我查阅MSDN帮助时,发现了Marshal类。该类概述描述道:提供了一个方法集,这些方法用于分配非托管内存、复制非托管内存块、将托管类型转换为非托管类型,此外还提供了在与非托管代码交互时使用的其他杂项方法。这时,我豁然开朗,觉得找到了一个托管代码与非托管代码交互的桥梁。

于是我声明COPYDATASTRUCT如下:

[StructLayout(LayoutKind.Sequential)]

public struct COPYDATASTRUCT

{

public IntPtr dwData;

public int cbData;

public IntPtr lpData;

}

在发送数据时,我使用Marshal类分配一块全局内存,并将数据拷入这块内存,然后发送消息:

COPYDATASTRUCT cds;

cds.dwData = (IntPtr)flag;

cds.cbData = data.Length;

cds.lpData = Marshal.AllocHGlobal(data.Length);

Marshal.Copy(data,0,cds.lpData,data.Length);

SendMessage(WINDOW_HANDLER,WM_COPYDATA,0,ref cds);

在接收数据时,我使用Marshal类将数据从这块全局内存拷出,然后处理消息:

COPYDATASTRUCT cds = new COPYDATASTRUCT();

    Type mytype = cds.GetType();

cds = (COPYDATASTRUCT)m.GetLParam(mytype);

uint flag = (uint)(cds.dwData);

byte[] bt = new byte[cds.cbData];

Marshal.Copy(cds.lpData,bt,0,bt.Length);

详细源码如下:

/// <summary>

/// Windows 的COPYDATA消息封装类。

/// </summary>

public class Messager : System.Windows.Forms.Form

{

/// <summary>

/// 必需的设计器变量。

/// </summary>

private System.ComponentModel.Container components = null;

//消息标识

private const int WM_COPYDATA = 0x004A;

//消息数据类型(typeFlag以上二进制,typeFlag以下字符)

private const uint typeFlag = 0x8000;

/// <summary>

/// 重载CopyDataStruct

/// </summary>

[StructLayout(LayoutKind.Sequential)]

public struct COPYDATASTRUCT

{

public IntPtr dwData;

public int cbData;

public IntPtr lpData;

}

//

[DllImport("User32.dll",EntryPoint="SendMessage")]

private static extern int SendMessage(

int hWnd,                                  // handle to destination window

int Msg,                              // message

int wParam,                               // first message parameter

ref COPYDATASTRUCT lParam    // second message parameter

);

//

[DllImport("User32.dll",EntryPoint="FindWindow")]

private static extern int FindWindow(string lpClassName,string lpWindowName);

//接收到数据委托与事件定义

public delegate void ReceiveStringEvent(object sender,uint flag,string str);

public delegate void ReceiveBytesEvent(object sender,uint flag,byte[] bt);

public event ReceiveStringEvent OnReceiveString;

public event ReceiveBytesEvent OnReceiveBytes;

//发送数据委托与事件定义

public delegate void SendStringEvent(object sender,uint flag,string str);

public delegate void SendBytesEvent(object sender,uint flag,byte[] bt);

public event SendStringEvent OnSendString;

public event SendBytesEvent OnSendBytes;

//

public Messager()

{

//

// Windows 窗体设计器支持所必需的

//

InitializeComponent();

//

// TODO: 在 InitializeComponent 调用后添加任何构造函数代码

//

}

/// <summary>

/// 清理所有正在使用的资源。

/// </summary>

protected override void Dispose( bool disposing )

{

if( disposing )

{

if(components != null)

{

components.Dispose();

}

}

base.Dispose( disposing );

}

#region Windows 窗体设计器生成的代码

/// <summary>

/// 设计器支持所需的方法 - 不要使用代码编辑器修改

/// 此方法的内容。

/// </summary>

private void InitializeComponent()

{

//

// Messager

//

this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);

this.ClientSize = new System.Drawing.Size(200, 14);

this.Name = "Messager";

this.ShowInTaskbar = false;

this.Text = "Demo_Emluator";

this.WindowState = System.Windows.Forms.FormWindowState.Minimized;

}

#endregion

/// <summary>

///重载窗口消息处理函数

/// </summary>

/// <param name="m"></param>

protected override void DefWndProc(ref System.Windows.Forms.Message m)

{

switch(m.Msg)

{

//接收CopyData消息,读取发送过来的数据

case WM_COPYDATA:

COPYDATASTRUCT cds = new COPYDATASTRUCT();

                          Type mytype = cds.GetType();

cds = (COPYDATASTRUCT)m.GetLParam(mytype);

uint flag = (uint)(cds.dwData);

byte[] bt = new byte[cds.cbData];

Marshal.Copy(cds.lpData,bt,0,bt.Length);

if(flag <= typeFlag)

{

if(OnReceiveString != null)

{

OnReceiveString(this,flag,System.Text.Encoding.Default.GetString(bt));

}

}

else

{

if(OnReceiveBytes != null)

{

OnReceiveBytes(this,flag,bt);

}

}

break;

default:

base.DefWndProc(ref m);

break;

}

}

/// <summary>

/// 发送字符串格式数据

/// </summary>

/// <param name="destWindow">目标窗口标题</param>

/// <param name="flag">数据标志</param>

/// <param name="str">数据</param>

/// <returns></returns>

public bool SendString(string destWindow,uint flag,string str)

{

if(flag > typeFlag)

{

MessageBox.Show("要发送的数据不是字符格式");

return false;

}

int WINDOW_HANDLER = FindWindow(null,@destWindow);

if(WINDOW_HANDLER == 0) return false;

try

{

byte[] sarr = System.Text.Encoding.Default.GetBytes(str);

COPYDATASTRUCT cds;

cds.dwData = (IntPtr)flag;

cds.cbData = sarr.Length;

cds.lpData = Marshal.AllocHGlobal(sarr.Length);

Marshal.Copy(sarr,0,cds.lpData,sarr.Length);

SendMessage(WINDOW_HANDLER,WM_COPYDATA,0,ref cds);

if(OnSendString != null)

{

OnSendString(this,flag,str);

}

return true;

}

catch(Exception e)

{

MessageBox.Show(e.Message);

return false;

}

}

/// <summary>

/// 发送二进制格式数据

/// </summary>

/// <param name="destWindow">目标窗口</param>

/// <param name="flag">数据标志</param>

/// <param name="data">数据</param>

/// <returns></returns>

public bool SendBytes(string destWindow,uint flag,byte[] data)

{

if(flag <= typeFlag)

{

MessageBox.Show("要发送的数据不是二进制格式");

return false;

}

int WINDOW_HANDLER = FindWindow(null,@destWindow);

if(WINDOW_HANDLER == 0) return false;

try

{

COPYDATASTRUCT cds;

cds.dwData = (IntPtr)flag;

cds.cbData = data.Length;

cds.lpData = Marshal.AllocHGlobal(data.Length);

Marshal.Copy(data,0,cds.lpData,data.Length);

SendMessage(WINDOW_HANDLER,WM_COPYDATA,0,ref cds);

if(OnSendBytes != null)

{

OnSendBytes(this,flag,data);

}

return true;

}

catch(Exception e)

{

MessageBox.Show(e.Message);

return false;

}

}

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