如何在C#用WM

來源:互聯網
上載者:User
進程|資料

簡介:

本文著重講述了如果用WM_COPYDATA訊息來實現兩個進程之間傳遞資料.

進程之間通訊的幾種方法:

在Windows程式中,各個進程之間常常需要交換資料,進行資料通訊。常用的方法有

  使用記憶體對應檔
  通過共用記憶體DLL共用記憶體
  使用SendMessage向另一進程發送WM_COPYDATA訊息

比起前兩種的複雜實現來,WM_COPYDATA訊息無疑是一種經濟實惠的一中方法.

WM_COPYDATA訊息的主要目的是允許在進程間傳遞唯讀資料。Windows在通過WM_COPYDATA訊息傳遞期間,不提供繼承同步方式。SDK文檔推薦使用者使用SendMessage函數,接受方在資料拷貝完成前不返回,這樣發送方就不可能刪除和修改資料:

這個函數的原型及其要用到的結構如下:

SendMessage(hwnd,WM_COPYDATA,wParam,lParam);
其中,WM_COPYDATA對應的十六進位數為0x004A

wParam設定為包含資料的視窗的控制代碼。lParam指向一個COPYDATASTRUCT的結構:
typedef struct tagCOPYDATASTRUCT{
    DWORD dwData;//使用者定義資料
    DWORD cbData;//資料大小
    PVOID lpData;//指向資料的指標
}COPYDATASTRUCT;
該結構用來定義使用者資料。

具體過程如下:


首先,在發送方,用FindWindow找到接受方的控制代碼,然後向接受方發送WM_COPYDATA訊息.

接受方在DefWndProc事件中,來處理這條訊息.由於中文編碼是兩個位元組,所以傳遞中文時候位元組長度要搞清楚.

代碼中有適量的解釋,大家請自己看吧.

具體代碼如下:
//---------------------------------------------------
//發送方:
//---------------------------------------------------

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)
   {
     //接收自訂訊息 USER,並顯示其參數
    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)
   {
     //接收自訂訊息 USER,並顯示其參數
    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;
 }
}



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