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;
}
}
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