(转载)在C#用WM_COPYDATA消息来实现两个进程之间传递数据

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原文地址:http://www.kehui.net/index.php?op=article&file=read&aid=16470

简介:

本文着重讲述了如果用WM_COPYDATA消息来实现两个进程之间传递数据.

进程之间通讯的几种方法:

在Windows程序中，各个进程之间常常需要交换数据，进行数据通讯。常用的方法有

使用内存映射文件
通过共享内存DLL共享内存
使用SendMessage向另一进程发送WM_COPYDATA消息

比起前两种的复杂实现来,WM_COPYDATA消息无疑是一种经济实惠的一中方法.

WM_COPYDATA消息的主要目的是允许在进程间传递只读数据。Windows在通过WM_COPYDATA消息传递期间，不提供继承同步方式。SDK文档推荐用户使用SendMessage函数，接受方在数据拷贝完成前不返回，这样发送方就不可能删除和修改数据：

这个函数的原型及其要用到的结构如下:

SendMessage(hwnd,WM_COPYDATA,wParam,lParam);
其中,WM_COPYDATA对应的十六进制数为0x004A

wParam设置为包含数据的窗口的句柄。lParam指向一个COPYDATASTRUCT的结构：
typedef struct tagCOPYDATASTRUCT{
    DWORD dwData;//用户定义数据
    DWORD cbData;//数据大小
    PVOID lpData;//指向数据的指针
}COPYDATASTRUCT;
该结构用来定义用户数据。

具体过程如下:

接受方在DefWndProc事件中,来处理这条消息.由于中文编码是两个字节,所以传递中文时候字节长度要搞清楚.

代码中有适量的解释,大家请自己看吧.

具体代码如下:

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Runtime.InteropServices;

namespace WindowsFormGetMsg
{
public class Form1 : System.Windows.Forms.Form
{
  private System.Windows.Forms.TextBox textBox1;
  private System.ComponentModel.Container components = null;
  const int WM_COPYDATA = 0x004A;

  public Form1()
  {
   InitializeComponent();
  }

  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #region Windows Form Designer generated code
  private void InitializeComponent()
  {
   this.textBox1 = new System.Windows.Forms.TextBox();
   this.SuspendLayout();
   //
   // textBox1
   //
   this.textBox1.Location = new System.Drawing.Point(176, 32);
   this.textBox1.Name = "textBox1";
   this.textBox1.Size = new System.Drawing.Size(160,

21);
   this.textBox1.TabIndex = 0;
   this.textBox1.Text = "textBox1";
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6,

14);
   this.ClientSize = new System.Drawing.Size(432, 266);
   this.Controls.AddRange(new

System.Windows.Forms.Control[] {




this.textBox1});
   this.Name = "Form1";
   this.Text = "接收方";
   this.ResumeLayout(false);

  }
  #endregion

  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }

  protected override void DefWndProc(ref

System.Windows.Forms.Message m)
  {
   switch(m.Msg)
   {
     //接收自定义消息 USER，并显示其参数
    case WM_COPYDATA:
     COPYDATASTRUCT mystr = new

COPYDATASTRUCT();
　　　    Type mytype = mystr.GetType();

　　　    mystr =(COPYDATASTRUCT)m.GetLParam(mytype);
     this.textBox1.Text =mystr.lpData;

     break;
    default:
     base.DefWndProc(ref m);
     break;

   }

  }

}
[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT
{
  public IntPtr dwData;
  public int cbData;
  [MarshalAs(UnmanagedType.LPStr)] public string lpData;
}
}

//---------------------------------------------------
//接受方
//---------------------------------------------------
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Runtime.InteropServices;

namespace WindowsFormGetMsg
{
public class Form1 : System.Windows.Forms.Form
{
  private System.Windows.Forms.TextBox textBox1;
  private System.ComponentModel.Container components = null;
  const int WM_COPYDATA = 0x004A;

  public Form1()
  {
   InitializeComponent();
  }

  protected override void Dispose( bool disposing )
  {
   if( disposing )
   {
    if (components != null)
    {
     components.Dispose();
    }
   }
   base.Dispose( disposing );
  }

  #region Windows Form Designer generated code
  private void InitializeComponent()
  {
   this.textBox1 = new System.Windows.Forms.TextBox();
   this.SuspendLayout();
   //
   // textBox1
   //
   this.textBox1.Location = new System.Drawing.Point

(176, 32);
   this.textBox1.Name = "textBox1";
   this.textBox1.Size = new System.Drawing.Size(160, 21);
   this.textBox1.TabIndex = 0;
   this.textBox1.Text = "textBox1";
   //
   // Form1
   //
   this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
   this.ClientSize = new System.Drawing.Size(432, 266);
   this.Controls.AddRange(new System.Windows.Forms.Control[] {this.textBox1});
   this.Name = "Form1";
   this.Text = "接收方";
   this.ResumeLayout(false);
  }
  #endregion

  [STAThread]
  static void Main()
  {
   Application.Run(new Form1());
  }

  protected override void DefWndProc(ref System.Windows.Forms.Message m)
  {
   switch(m.Msg)
   {
     //接收自定义消息 USER，并显示其参数
    case WM_COPYDATA:
     COPYDATASTRUCT mystr = new COPYDATASTRUCT();
　　　    Type mytype = mystr.GetType();

     mystr =(COPYDATASTRUCT)m.GetLParam(mytype);
     this.textBox1.Text =mystr.lpData;

     break;
    default:
     base.DefWndProc(ref m);
     break;
   }
  }
}

[StructLayout(LayoutKind.Sequential)]
public struct COPYDATASTRUCT
{
  public IntPtr dwData;
  public int cbData;
  [MarshalAs(UnmanagedType.LPStr)] public string lpData;
}
}

//---------------------------------------------------
//发送方:
//---------------------------------------------------

首先,在发送方,用FindWindow找到接受方的句柄,然后向接受方发送WM_COPYDATA消息.