一、引言
fanout类型的Exchange，路由规则非常简单：它会把所有发送到该Exchange的消息，路由到所有与它绑定的Queue中。假设有一个聊天室，各个客户端都订阅在同一fanout exchange type，那每个客户端发送出来的消息，所有的客户端都能收到，因为大家都订阅了。此时，只需要简单地限制一下，只有是与我有关的消息，才在聊天界面上显示。这样，即可达到相互通讯的效果。
二、示例
2.1、环境准备
本示例使用EasyNetQ来实现，请先在NuGet上安装。
2.2、实体类
新建一个实体类MessageBody：
public class MessageBody
{
public string FromUserId { get; set; }
public string Message { get; set; }
public string ToUserId { get; set; }
}
2.3、主窗体
新建一个ChatMain窗体：
代码如下：
public partial class ChatMain : Form
{
public ChatMain()
{
InitializeComponent();
}
/// <summary>
/// 客户端 A
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Button1_Click(object sender, EventArgs e)
{
ChatWith chatWith = new ChatWith(currentUserId: "UserA")
{
StartPosition = FormStartPosition.CenterScreen
};
chatWith.Show();
}
/// <summary>
/// 客户端 B
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Button2_Click(object sender, EventArgs e)
{
ChatWith chatWith = new ChatWith(currentUserId: "UserB")
{
StartPosition = FormStartPosition.CenterScreen
};
chatWith.Show();
}
/// <summary>
/// 客户端 C
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Button3_Click(object sender, EventArgs e)
{
ChatWith chatWith = new ChatWith(currentUserId: "UserC")
{
StartPosition = FormStartPosition.CenterScreen
};
chatWith.Show();
}
/// <summary>
/// 客户端 D
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void Button4_Click(object sender, EventArgs e)
{
ChatWith chatWith = new ChatWith(currentUserId: "UserD")
{
StartPosition = FormStartPosition.CenterScreen
};
chatWith.Show();
}
}
2.4、客户端窗体
新建一个ChatWith窗体：
代码如下：
public partial class ChatWith : Form
{
public delegate void ChatWithDelegate();
public delegate void ChatWithDelegate<T1>(T1 obj1);
public delegate void ChatWithDelegate<T1, T2>(T1 obj1, T2 obj2);
public string CurrentUserId { get; }
private IBus bus;
public const string ConnStringMQ = "host=192.168.2.242:5672,192.168.2.165:5672;virtualHost=/;username=hello;password=world";
public const string FanoutExchange = "fanoutEC";
/// <summary>
/// 有参构造函数
/// </summary>
/// <param name="currentUserId"></param>
public ChatWith(string currentUserId)
{
InitializeComponent();
//在多线程程序中，新创建的线程不能访问UI线程创建的窗口控件。
//此时若想访问窗体的控件，可将窗体构造函数中的CheckForIllegalCrossThreadCalls设置为false。
//这时线程就能安全地访问窗体控件了。
CheckForIllegalCrossThreadCalls = false;
CurrentUserId = currentUserId;
}
/// <summary>
/// ShowMessage重载
/// </summary>
/// <param name="msg"></param>
private void ShowMessage(string msg)
{
if (InvokeRequired)//InvokeRequired：当前线程不是创建控件的线程时为true
{
BeginInvoke(new ChatWithDelegate<string>(ShowMessage), msg);
}
else
{
ListViewItem item = new ListViewItem(new string[] { DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), msg });
lvwReceiveMsg.Items.Insert(0, item);
}
}
/// <summary>
/// ShowMessage重载
/// </summary>
/// <param name="toUserId"></param>
/// <param name="msg"></param>
private void ShowMessage(string toUserId, string msg)
{
if (InvokeRequired)
{
BeginInvoke(new ChatWithDelegate<string, string>(ShowMessage), toUserId, msg);
}
else
{
ListViewItem item = new ListViewItem(new string[] { DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss"), toUserId, msg });
lvwReceiveMsg.Items.Insert(0, item);
}
}
/// <summary>
/// 绑定队列并订阅
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void ChatWith_Load(object sender, EventArgs e)
{
cmbOnLine.SelectedIndex = 0;
Text = Text + $"[{CurrentUserId}]";
//这里不能使用using，否则订阅者立即就释放了，订阅不到消息。
bus = RabbitHutch.CreateBus(ConnStringMQ);
{
if (bus.IsConnected)
{
var exchange = bus.Advanced.ExchangeDeclare(name: FanoutExchange, type: ExchangeType.Fanout);
var queue = bus.Advanced.QueueDeclare(name: $"{FanoutExchange}_queue_{CurrentUserId}");
bus.Advanced.Bind(exchange: exchange, queue: queue, routingKey: "");
bus.Advanced.Consume(queue, registration =>
{
registration.Add<MessageBody>((message, info) =>
{
if (message.Body.ToUserId == CurrentUserId)
{
ShowMessage(message.Body.FromUserId, message.Body.Message);
}
});
});
}
else
{
ShowMessage("服务器连接失败。");
}
}
}
/// <summary>
/// 发送
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btnSend_Click(object sender, EventArgs e)
{
try
{
using (var bus = RabbitHutch.CreateBus(ConnStringMQ))
{
if (bus.IsConnected)
{
if (cmbOnLine.Text == "*")//群发
{
foreach (var item in cmbOnLine.Items.Cast<string>().Where(s => s != "*" && s != CurrentUserId))
{
var exchange = bus.Advanced.ExchangeDeclare(name: FanoutExchange, type: ExchangeType.Fanout);
var messageBody = new MessageBody
{
FromUserId = CurrentUserId,
Message = txtSendMsg.Text,
ToUserId = item
};
bus.Advanced.Publish(exchange: exchange,
routingKey: "",
mandatory: false,
message: new Message<MessageBody>(messageBody));
}
}
else//私聊
{
var exchange = bus.Advanced.ExchangeDeclare(name: FanoutExchange, type: ExchangeType.Fanout);
var messageBody = new MessageBody
{
FromUserId = CurrentUserId,
Message = txtSendMsg.Text,
ToUserId = cmbOnLine.Text
};
bus.Advanced.Publish(exchange: exchange,
routingKey: "",
mandatory: false,
message: new Message<MessageBody>(messageBody));
}
}
else
{
ShowMessage("发送消息失败。");
}
}
}
catch (Exception ex)
{
ShowMessage(ex.Message);
}
}
/// <summary>
/// 关闭
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btnClose_Click(object sender, EventArgs e)
{
Close();
}
/// <summary>
/// 窗体关闭事件
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void ChatWith_FormClosed(object sender, FormClosedEventArgs e)
{
bus?.Dispose();
}
}
2.5、运行结果
