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:
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.
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://---------------------------------------------------//发送方://---------------------------------------------------
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; }}
