簡介

中介者模式（Mediator Pattern）是一種行為型模式，它限制物件之間的直接互動，它用一個中介物件來封裝一系列的動作，以讓物件之間進行交流，中介者使各個物件不需要顯式地相互參考，從而使其耦合松散，而且可以獨立地改變它們之間的互動，

當一些物件和其他物件緊密耦合以致難以對其進行修改時，或當組件因過于依賴其他組件而無法在不同應用中復用時，可使用中介者模式，

作用

用來降低多個物件和類之間的通信復雜性，
物件之間不再顯式地相互參考，但可以獨立地改變它們之間的互動，從而保持松耦合，

實作步驟

定義一個工具介面，供不同工具類來實作，建立多個具體工具類實作基礎工具介面，
定義一個基礎抽象類，里面聚合了工具介面，相當于橋接，
再重新定義一個新抽象類，繼承自基礎抽象類，并補充一些方法，
建立具體物件類繼承新抽象類，呼叫橋接介面里的方法來實作功能，

UML

Java代碼

中介者抽象介面

 

// RoomMediator.java 定義中介者介面或抽象類
public interface RoomMediator {
   public void register(AbstractUser user);
   public void sendTo(AbstractUser from, AbstractUser to, String message);
   public void send(AbstractUser from, String message);
}

通用中介者

// GeneralRoom.java 中介者的具體實作類
public class GeneralRoom implements RoomMediator {
   public List<AbstractUser> users = new ArrayList<AbstractUser>();

   @Override
   public void register(AbstractUser user) {
      // 用戶注冊登記，追加用戶串列
      user.setRoomMediator(this);
      users.add(user);
   }

   // 作為中介者通知給某個用戶
   @Override
   public void sendTo(AbstractUser from, AbstractUser to, String message) {
      System.out.println(
            "GeneralRoom:sendTo() [from: " + from.getName() + " message: " + message + " to: " + to.getName() + " ]");
      // 根據用戶名稱定向發送
      to.recieve(from, message);
   }

   // 作為中介者通知給全體用戶
   @Override
   public void send(AbstractUser from, String message) {
      System.out.println("GeneralRoom:send() [from: " + from.getName() + " message: " + message + "]");
      for (AbstractUser user : users) {
         user.recieve(from, message);
      }
   }
}

抽象用戶類

// AbstractUser.java 定義抽象用戶類，聚合中介者
public abstract class AbstractUser {

   private String name;
   public RoomMediator roomMediator;

   public AbstractUser(String name) {
      this.name = name;
   }

   public void setRoomMediator(RoomMediator roomMediator) {
      this.roomMediator = roomMediator;
   }

   public abstract void send(String message);

   public abstract void sendTo(AbstractUser to, String message);

   public abstract void recieve(AbstractUser from, String message);

   public String getName() {
      return this.name;
   }
}

具體用戶物件

// CommonUser.java 普通用戶繼承了抽象用戶，實作了具體功能
public class CommonUser extends AbstractUser {

   public CommonUser(String name) {
      super(name);
   }

   @Override
   public void send(String message) {
      System.out.println("CommonUser:send() [user: " + this.getName() + " message:" + message + "]");
      // 通過中介者來中轉訊息
      this.roomMediator.send(this, message);
   }

   @Override
   public void sendTo(AbstractUser to, String message) {
      System.out.println("CommonUser:sendTo() [user: " + this.getName() + " message:" + message + " to: " + to.getName() + "]");
      // 通過中介者來中轉訊息
      this.roomMediator.sendTo(this, to, message);
   }

   @Override
   public void recieve(AbstractUser from, String message) {
      System.out.println("CommonUser:recieve() [user: " + this.getName() + " message: " + message + " from:" + from.getName() + "]");
   }
}

// MemberUser.java 會員用戶繼承了抽象用戶，實作了具體功能
public class MemberUser extends AbstractUser {
   public MemberUser(String name) {
      super(name);
   }

   @Override
   public void send(String message) {
      System.out.println("MemberUser:send() [user: " + this.getName() + " message:" + message + "]");
      // 通過中介者來中轉訊息
      this.roomMediator.send(this, message);
   }

   @Override
   public void sendTo(AbstractUser to, String message) {
      System.out
            .println("MemberUser:sendTo() [user: " + this.getName() + " message:" + message + " to: " + to.getName() + "]");
      // 通過中介者來中轉訊息
      this.roomMediator.sendTo(this, to, message);
   }

   @Override
   public void recieve(AbstractUser from, String message) {
      System.out.println("MemberUser:recieve() [user: " + this.getName() + " message: " + message
            + " from user:" + from.getName() + "]");
   }

}

測驗呼叫

public class Test {

  public static void start() {
  /**
   * 中介者模式用一個中介物件來封裝一系列動作，讓物件之間利用中介者來交流，
   * 這里聊天室就是一個中介者，用戶和用戶之間的訊息傳遞，全部依靠聊天室來完成，
   * 先給聊天室注冊用戶，也給用戶系結上中介者，雙方彼此持有關系，
   * 中介者的成員之間的訊息傳遞通過中介者來代理傳達，
   */

    // 宣告一個聊天室
    GeneralRoom generalRoom = new GeneralRoom();
    // 給聊天室添加點不同的人
    AbstractUser user1 = new CommonUser("user1");
    generalRoom.register(user1);
    CommonUser user2 = new CommonUser("user2");
    generalRoom.register(user2);
    MemberUser user3 = new MemberUser("user3");
    generalRoom.register(user3);

    // user1 發送給全體
    user1.send("hi, I'm " + user1.getName() + ".");
    // user2 發送給 user3
    user2.sendTo(user3, "haha.");

  }

  public static void main(String[] args) {
    System.out.println("test start:");
    start();
  }

}

Go代碼

中介者抽象介面

 

// RoomMediator.go 定義中介者介面或抽象類
type RoomMediator interface {
  Register(user AbstractUser)
  SendTo(from AbstractUser, to AbstractUser, message string)
  Send(from AbstractUser, message string)
}

通用中介者

// GeneralRoom.go 中介者的具體實作類
type GeneralRoom struct {
  users []AbstractUser
}

func (g *GeneralRoom) Register(user AbstractUser) {
  // 用戶注冊登記，追加用戶串列
  user.SetRoomMediator(g)
  g.users = append(g.users, user)
}

// 作為中介者通知給某個用戶
func (g *GeneralRoom) SendTo(from AbstractUser, to AbstractUser, message string) {
  fmt.Println("GeneralRoom::SendTo() [from: " + from.GetName() + " message: " + message + " to: " + to.GetName() + "]")
  // 定向發送給某個用戶，名稱唯一
  to.Recieve(from, message)
}

// 作為中介者通知給全體用戶
func (g *GeneralRoom) Send(from AbstractUser, message string) {
  fmt.Println("GeneralRoom::Send() [from: " + from.GetName() + " message: " + message + "] ")
  for _, user := range g.users {
    user.Recieve(from, message)
  }
}

抽象用戶類

 

// AbstractUser.go 定義抽象用戶類，聚合中介者
type AbstractUser interface {
  SetRoomMediator(roomMediator RoomMediator)
  Send(message string)
  SendTo(to AbstractUser, message string)
  Recieve(from AbstractUser, message string)
  GetName() string
}

具體用戶物件

// CommonUser.go 普通用戶繼承了抽象用戶，實作了具體功能
type CommonUser struct {
  Name         string
  roomMediator RoomMediator
}

func (c *CommonUser) SetRoomMediator(roomMediator RoomMediator) {
  c.roomMediator = roomMediator
}

func (c *CommonUser) Send(message string) {
  fmt.Println("CommonUser:Send() [user: " + c.GetName() + " message: " + message + "]")
  // 通過中介者來中轉訊息
  c.roomMediator.Send(c, message)
}

func (c *CommonUser) SendTo(to AbstractUser, message string) {
  fmt.Println("CommonUser:SendTo() [user: " + c.GetName() + " message: " + message + "]")
  // 通過中介者來中轉訊息
  c.roomMediator.SendTo(c, to, message)
}

func (c *CommonUser) Recieve(from AbstractUser, message string) {
  fmt.Println("CommonUser:Recieve() [user: " + c.GetName() + " message: " + message + " from: " + from.GetName() + "]")
}

func (c *CommonUser) SetName(name string) {
  c.Name = name
}

func (c *CommonUser) GetName() string {
  return c.Name
}

// MemberUser.go 會員用戶繼承了抽象用戶，實作了具體功能
type MemberUser struct {
  // Name首字母大寫以便跨模塊訪問
  Name         string
  roomMediator RoomMediator
}

func (c *MemberUser) SetRoomMediator(roomMediator RoomMediator) {
  c.roomMediator = roomMediator
}

func (c *MemberUser) Send(message string) {
  fmt.Println("MemberUser:Send() [user: " + c.GetName() + " message: " + message + "]")
  // 通過中介者來中轉訊息
  c.roomMediator.Send(c, message)
}

func (c *MemberUser) SendTo(to AbstractUser, message string) {
  fmt.Println("MemberUser:SendTo() [user: " + c.GetName() + " message: " + message + "]")
  // 通過中介者來中轉訊息
  c.roomMediator.SendTo(c, to, message)
}

func (c *MemberUser) Recieve(from AbstractUser, message string) {
  fmt.Println("MemberUser:Recieve() [user: " + c.GetName() + " message: " + message + " from: " + from.GetName() + "]")
}

func (c *MemberUser) SetName(name string) {
  c.Name = name
}

func (c *MemberUser) GetName() string {
  return c.Name
}

測驗呼叫

func main() {
  fmt.Println("test start:")
  /**
   * 中介者模式用一個中介物件來封裝一系列動作，讓物件之間利用中介者來交流，
   * 這里聊天室就是一個中介者，用戶和用戶之間的訊息傳遞，全部依靠聊天室來完成，
   * 先給聊天室注冊用戶，也給用戶系結上中介者，雙方彼此持有關系，
   * 中介者的成員之間的訊息傳遞通過中介者來代理傳達，
   */
  // 宣告一個聊天室
  var generalRoom = new(src.GeneralRoom)
  // 給聊天室添加點不同的人
  var user1 = &src.CommonUser{
    Name: "user1",
  }
  generalRoom.Register(user1)

  var user2 = &src.CommonUser{
    Name: "user2",
  }
  generalRoom.Register(user2)

  var user3 = &src.MemberUser{
    Name: "user3",
  }
  generalRoom.Register(user3)

  // user1 發送給全體
  user1.Send("hi, I'm " + user1.GetName() + ".")
  // user2 發送給 user3
  user2.SendTo(user3, "haha.")
}

C語言簡版

#include <stdio.h>

/**
 * 中介者模式是一種行為型設計模式，它可以用來減少類之間的直接依賴關系，
 * 將物件之間的通信封裝到一個中介者物件中，從而使得各個物件之間的關系更加松散，
 * 在中介者模式中，物件之間不再直接相互互動，而是通過中介者來中轉訊息，
 */

typedef struct Colleague Colleague;
typedef struct Mediator Mediator;

// 定義抽象互動物件類
struct Colleague
{
  int id;
  struct Mediator *mediator;
  void (*send)(struct Colleague *sender, char *message);
  void (*send_to)(struct Colleague *sender, Colleague *receiver, char *message);
  void (*receive)(struct Colleague *receiver, Colleague *sender, char *message);
};

// 定義中介者類
struct Mediator
{
  struct Colleague **colleagues;
  int colleagues_length;
  void (*send)(Colleague *sender, char *message);
  void (*send_to)(Colleague *sender, Colleague *receiver, char *message);
};

// 互動物件發送訊息
void colleague_send(Colleague *sender, char *message)
{
  printf("\r\n colleague_send() [sender->id=%d message=%s]", sender->id, message);
  Mediator *mediator = sender->mediator;
  // 由中介者代為轉發訊息給全體接收者
  mediator->send(sender, message);
}

// 互動物件發送訊息
void colleague_send_to(Colleague *sender, Colleague *receiver, char *message)
{
  printf("\r\n colleague_send_to() [sender->id=%d receiver->id=%d message=%s]", sender->id, receiver->id, message);
  Mediator *mediator = sender->mediator;
  // 由中介者代為轉發訊息給指定接收者
  mediator->send_to(sender, receiver, message);
}

// 物件接收訊息
void colleague_receive(Colleague *receiver, Colleague *sender, char *message)
{
  printf("\r\n colleague_receive() [receiver->id=%d send->id=%d message=%s]", receiver->id, sender->id, message);
}

// 中介者發送訊息
void mediator_send(Colleague *sender, char *message)
{
  printf("\r\n mediator_send() [sender->id=%d message=%s]", sender->id, message);
  Colleague *receiver;
  for (int i = 0; i < sender->mediator->colleagues_length; i++)
  {
    // 中介者通知全體接收者
    receiver = sender->mediator->colleagues[i];
    receiver->receive(receiver, sender, message);
  }
}

// 中介者發送訊息
void mediator_send_to(Colleague *sender, Colleague *receiver, char *message)
{
  // 中介者通知指定接收者
  printf("\r\n mediator_send_to() [sender->id=%d receiver->id=%d message=%s]", sender->id, receiver->id, message);
  receiver->receive(receiver, sender, message);
}

// 初始化互動物件類
void colleague_constructor(Colleague *self, int id)
{
  self->id = id;
  self->send = colleague_send;
  self->send_to = colleague_send_to;
  self->receive = colleague_receive;
}

// 初始化中介者類
void mediator_constructor(Mediator *self, Colleague **colleagues, int colleagues_length)
{
  self->colleagues = colleagues;
  self->colleagues_length = colleagues_length;
  // 給每個物件系結中介者
  for (int i = 0; i < self->colleagues_length; i++)
  {
    self->colleagues[i]->mediator = self;
  }
  self->send = &mediator_send;
  self->send_to = &mediator_send_to;
}

// test

int main()
{
  // 初始化具體互動物件a，分別系結相關函式
  Colleague colleague_a;
  colleague_constructor(&colleague_a, 1);

  // 初始化具體互動物件b，分別系結相關函式
  Colleague colleague_b;
  colleague_constructor(&colleague_b, 2);

  // 定義互動物件陣列
  Colleague *colleagues[] = {&colleague_a, &colleague_b};
  int colleagues_length = sizeof(colleagues) / sizeof(colleagues[0]);

  printf("colleagues_length=%d", colleagues_length);

  // 初始化中介者類，系結互動物件
  Mediator mediator;
  mediator_constructor(&mediator, colleagues, colleagues_length);

  // 互動類發送訊息
  colleague_a.send(&colleague_a, "Hi, all! I'm a.");
  printf("\r\n ==== \r\n");
  colleague_a.send_to(&colleague_a, &colleague_b, "Hello, colleague_b. I am a!");
  printf("\r\n ==== \r\n");
  colleague_b.send_to(&colleague_b, &colleague_a, "Hi, colleague_a! I'm b.");
  return 0;
}

【中介者設計模式詳解】C/Java/JS/Go/Python/TS不同語言實作

簡介

作用

實作步驟

UML

Java代碼

中介者抽象介面

通用中介者

抽象用戶類

具體用戶物件

測驗呼叫

Go代碼

中介者抽象介面

通用中介者

抽象用戶類

具體用戶物件

測驗呼叫

C語言簡版

更多語言版本