两个exe程序之间通信

# Windows消息
```java
//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
 }
```
```java

//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
  }
```

![](/media/202409/2024-09-20_191552_7601650.6269394623902169.gif)

# 简单的操作其他程序

首先要指明一点，此操作都是基于句柄的，但是现在有很多程序的控件都是自绘的，所以是没有句柄的。

实现功能：

- 设置QQ窗口显示/隐藏（如果支持的化）
- 设置QQ窗口最大化/最小化
- 自定义设置QQ窗口的标题
- 在输入控件中输入内容并回车

```java
#region 设置窗口标题

[DllImport("User32.dll")]
private static extern int SendMessage(int hWnd, int msg, int wParam, String lParam);

const int WM_SETTEXT = 0x000C;
private void btnSetTitle_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    SendMessage(handle, WM_SETTEXT, 0, txtTitle.Text);
}

#endregion

#region 设置窗口显示隐藏
[DllImport("user32.dll")]
public static extern bool SendMessage(int hWnd, int msg, Boolean wParam, int lParam);

const int WM_SHOWWINDOW = 0x18;

private void btnShow_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    SendMessage(handle, WM_SHOWWINDOW, true, 0);
}

private void btnHide_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    SendMessage(handle, WM_SHOWWINDOW, false, 0);
}

#endregion

#region 输入内容
/// <summary>
/// 查找子窗口句柄
/// </summary>
/// <param name="hwndParent"></param>
/// <param name="hwndChildAfter"></param>
/// <param name="lpszClass"></param>
/// <param name="lpszWindow"></param>
/// <returns></returns>
[DllImport("user32.dll")]
private static extern int FindWindowEx(int hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

[DllImport("User32.dll")]
private static extern int SendMessage(int hWnd, int msg, int wParam, int lParam);
const int WM_CHAR = 0x102;
private void button1_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    int textHandle = FindWindowEx(handle, IntPtr.Zero, "Edit", "");
    SendMessage(textHandle, WM_SETTEXT, 0, txtContent.Text);
    System.Threading.Thread.Sleep(1000);
    SendMessage(textHandle, WM_CHAR, 13, 0);

}

#endregion

#region 最大最小化
const int SC_MINIMIZE = 0xF020;
const int SC_MAXIMIZE = 0xF030;
const int WM_SYSCOMMAND = 0x112;
private void btnMax_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    SendMessage(handle, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
}

private void btnMini_Click(object sender, EventArgs e)
{
    int handle = int.Parse(txtHandle.Text, System.Globalization.NumberStyles.AllowHexSpecifier);
    SendMessage(handle, WM_SYSCOMMAND, SC_MINIMIZE, 0);
}
#endregion
```

![](/media/202409/2024-09-20_192248_8840150.19374003729722233.gif)

以上句柄是我预先用SPY++抓好了的，也可以自己用FindWindow根据标题查找，由于QQ界面的渲染方式可能是动态的，所以这里设置标题实际是成功了的，可以看下图状态栏的名称。

还是上面写的问题，QQ没有输入框的句柄，所以输入这里我使用了记事本来实现效果，当然如果是winform程序，一般也是没问题的。更多的SendMessage的用法，大家也可以自行去百度。