C# 跨进程通信

  IM项目刚开始，由于IM客户端要与VMEETING通信，所以就做了技术调研，跨进程通信，我们使用的是windows  api的findwindow找到窗口，然后用send message通信。（此方案只适用于接收端有window的场景）

接收端代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;
namespace ProcessServer
{
    public partial class FrmProcessServer : Form
    {
        public FrmProcessServer()
        {
            InitializeComponent();
        }
        #region const data
        const int WM_COPYDATA = 0x004A;
        public struct COPYDATASTRUCT
        {
            public IntPtr dwData;
            public int cbData;
            [MarshalAs(UnmanagedType.LPStr)]
            public string lpData;
        }
        #endregion
        [DllImport("user32")]
        public static extern bool ChangeWindowMessageFilter(uint msg, int flags);  
        #region windows api functions
       
        protected override void DefWndProc(ref System.Windows.Forms.Message m)
        {
            switch (m.Msg)
            {
                case WM_COPYDATA:
                    COPYDATASTRUCT mystr = new COPYDATASTRUCT();
                    Type mytype = mystr.GetType();
                    mystr = (COPYDATASTRUCT)m.GetLParam(mytype);
                    File.WriteAllText("D:/processText.txt", "recieved:" + mystr.lpData);
                    lstMessageList.Items.Add(mystr.lpData);
                    break;
                default:
                    base.DefWndProc(ref m);
                    break;
            }
        }
        #endregion
        private void btnListen_Click(object sender, EventArgs e)
        {
        }
        private void FrmProcessServer_Load(object sender, EventArgs e)
        {
            ChangeWindowMessageFilter(WM_COPYDATA, 1);
        }
    }
}

发送端代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace ProcessClient
{
    public partial class FrmClientSender : Form
    {
        public FrmClientSender()
        {
            InitializeComponent();
        }
        //define const datas
        const int WM_COPYDATA = 0x004A;
        
        public enum ChangeWindowMessageFilterFlags : uint
        {
            Add = 1, Remove = 2
        };
        public struct COPYDATASTRUCT
        {
            public IntPtr dwData;
            public int cbData;
            [MarshalAs(UnmanagedType.LPStr)]
            public string lpData;
        }
        #region Dll Import
        [DllImport("User32.dll", EntryPoint = "FindWindow")]
        private static extern IntPtr FindWindow(string lpClassName,
    string lpWindowName);
        [DllImport("user32.dll", EntryPoint = "FindWindowEx")]
        private static extern IntPtr FindWindowEx(IntPtr hwndParent,
    IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
        [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")]
        public static extern bool PostMessage(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam); 
        [DllImport("user32")]
        public static extern uint RegisterWindowMessage(string msg);
        [DllImport("user32")]
        public static extern bool ChangeWindowMessageFilter(uint msg, ChangeWindowMessageFilterFlags flags);  
        #endregion
        #region public methods
        private static void SendMessageToProcess(string processWindowName, string message)
        {
           
            IntPtr WINDOWHANDLER = FindWindow(null, processWindowName);
            if ((int)WINDOWHANDLER == 0)
            {
                MessageBox.Show("reciver not found!");
            }
            else
            {
                //send message
                byte[] sarr = System.Text.Encoding.Default.GetBytes(message);
                int len = sarr.Length;
                COPYDATASTRUCT cds;
                cds.dwData = (IntPtr)100;
                cds.lpData = message;
                cds.cbData = len + 1;
                SendMessage((int)WINDOWHANDLER, WM_COPYDATA, 0, ref cds);
            }
        
        }
        #endregion
        private void FrmClientSender_Load(object sender, EventArgs e)
        {
        }
        private void btnSend_Click(object sender, EventArgs e)
        {
            SendMessageToProcess(txtReciver.Text, txtMessage.Text);
        }
    }
}
 

注：vista或win7中引入了uac机制，当以管理员身份运行时，仅仅调用send message这个api给接收端发是收不到的，接收端需要加上这句： ChangeWindowMessageFilter(WM_COPYDATA, 1) //告诉操作系统那条消息不要被过滤掉。