Golang如何使用中介者模式降低对象耦合_Golang Mediator模式应用方法

package main

import "fmt"

// 用户接口
type User interface {
    GetName() string
    Receive(message, from string)
    Send(to string, message string)
}

// 聊天室作为中介者
type ChatRoom struct {
    users map[string]User
}

func NewChatRoom() *ChatRoom {
    return &ChatRoom{
        users: make(map[string]User),
    }
}

func (c *ChatRoom) Register(user User) {
    c.users[user.GetName()] = user
}

func (c *ChatRoom) SendMessage(from, to, msg string) {
    sender, exists := c.users[from]
    if !exists {
        fmt.Printf("用户 %s 不在聊天室中\n", from)
        return
    }

    if to == "" {
        // 群发
        for name, user := range c.users {
            if name != from {
                user.Receive(msg, from)
            }
        }
        return
    }

    // 发送给指定用户
    receiver, exists := c.users[to]
    if !exists {
        sender.Receive(fmt.Sprintf("用户 %s 不存在", to), "系统")
        return
    }
    receiver.Receive(msg, from)
}

// 具体用户实现
type ChatUser struct {
    name     string
    mediator *ChatRoom
}

func NewChatUser(name string, room *ChatRoom) *ChatUser {
    user := &ChatUser{
        name:     name,
        mediator: room,
    }
    room.Register(user)
    return user
}

func (u *ChatUser) GetName() string {
    return u.name
}

func (u *ChatUser) Send(to, message string) {
    u.mediator.SendMessage(u.name, to, message)
}

func (u *ChatUser) Receive(message, from string) {
    fmt.Printf("[%s] 收到来自 %s 的消息: %s\n", u.name, from, message)
}

func main() {
    room := NewChatRoom()

    alice := NewChatUser("Alice", room)
    bob := NewChatUser("Bob", room)
    charlie := NewChatUser("Charlie", room)

    alice.Send("", "大家好！")           // 群发
    bob.Send("Charlie", "你好，Charlie！") // 私聊
}

[Bob] 收到来自 Alice 的消息: 大家好！
[Charlie] 收到来自 Alice 的消息: 大家好！
[Charlie] 收到来自 Bob 的消息: 你好，Charlie！