观察者模式

　　由于项目需要，用到了简单的观察者模式，项目中要求主窗口收到消息后，将消息派送出去，然后订阅了消息的窗口接受到消息，如下图所示。

    代码实现：

        1.新建一个中间类Watcher

/// <summary>
/// 定义发布消息的委托
/// </summary>
/// <param name="sender">发布者</param>
/// <param name="msg">消息</param>
public delegate void OnSend(object sender, string msg);

 public class Watcher
{
    /// <summary>
    /// 消息发布的事件
    /// </summary>
    public static event OnSend messageChange;

    public static void SendMessage(object sender, string msg)
    {
         if (messageChange != null)
        {
            messageChange(sender, msg);
        }
    }
}

2.主窗口接收到消息后派发消息

 

protected override void DefWndProc(ref System.Windows.Forms.Message m)
{
     switch (m.Msg)
      {
          case 0x004A:
              // 将返回信息发送给所有能接收CAD消息的窗口
              Watcher.SendMessage(this, mystr.lpData);
              break;
          default:
             base.DefWndProc(ref m);
             break;
     }
}

 3.在接收窗口订阅消息和接收消息

 

public ImportTrainControlData()
{
    InitializeComponent();
    // 订阅消息
    Watcher.messageChange += new OnSend(ReciveMessage);
}
 
/// <summary>
/// 接收消息
/// </summary>
/// <param name="sender"></param>
/// <param name="msg">消息内容</param>
void ReciveMessage(object sender, string msg)
{
    // frmMain 为主窗口
    frmMain _frmMain = sender as frmMain;
    if (_frmMain != null)
    {
        var keyCode = JsonHelper.GetKeyCode(msg);
        if (keyCode == "LoadDisplayDataTable")
        {
            var info = ObjectFactory.GetService<ICADAPI>().getDisplayDataTable(msg);
            BindData(info);
        }
    }
}