C#实现两个exe程序之间通信详解

//第一个客户端的代码
 /// <summary>
 /// 发送消息
 /// </summary>
 /// <param name="hWnd">发送窗口句柄</param>
 /// <param name="msg">发送的消息类型</param>
 /// <param name="wParam">附加消息,根据msg参数区分使用</param>
 /// <param name="lParam">发送数据</param>
 /// <returns></returns>
 [DllImport("User32.dll", EntryPoint = "SendMessage")]
 private static extern int SendMessage(int hWnd, int msg, int wParam, ref COPYDATASTRUCT lParam);
 /// <summary>
 /// 查找窗口句柄
 /// </summary>
 /// <param name="lpClassName">类名</param>
 /// <param name="lpWindowName">窗口标题</param>
 /// <returns></returns>
 [DllImport("User32.dll", EntryPoint = "FindWindow")]
 private static extern int FindWindow(string lpClassName, string lpWindowName);
 //当一个应用程序传递数据给另一个应用程序时发送此消息
 const int WM_COPYDATA = 0x004A;
 private void btnSend_Click(object sender, EventArgs e)
 {
     //根据标题查找到句柄
     int hWnd = FindWindow(null, "客户端2");
     //组织数据
     COPYDATASTRUCT cds;
     cds.dwData = 0;
     cds.cbData = System.Text.Encoding.Default.GetBytes(txtMsg.Text).Length + 1;
     cds.lpData = txtMsg.Text;
     //发送
     SendMessage(hWnd, WM_COPYDATA, 0, ref cds);
 }
 public struct COPYDATASTRUCT
 {
     public int dwData;//若发送较小数据可用此字段传输
     public int cbData;//发送数据的大小（以字节为单位）
     [MarshalAs(UnmanagedType.LPStr)]
     public string lpData;//发送数据
 }

//第二个客户端的代码
const int WM_COPYDATA = 0x004A;
  /// <summary>
  /// 重新DefWndProc方法，处理接收到的windows消息
  /// </summary>
  /// <param name="m"></param>
  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);
              txtMsg.Text = myStr.lpData;
              break;
          default:
              base.DefWndProc(ref m);
              break;
      }
  }
  public struct COPYDATASTRUCT
  {
      public int dwData;//若发送较小数据可用此字段传输
      public int cbData;//发送数据的大小（以字节为单位）
      [MarshalAs(UnmanagedType.LPStr)]
      public string lpData;//发送数据
  }