Design Pattern 简明教程
Design Patterns - Mediator Pattern
中介者模式用于减少多个对象或类之间的通信复杂性。此模式提供一个中介者类，它通常处理不同类之间的所有通信，并通过松耦合来支持轻松维护代码。中介者模式归属于行为模式类别。
Mediator pattern is used to reduce communication complexity between multiple objects or classes. This pattern provides a mediator class which normally handles all the communications between different classes and supports easy maintenance of the code by loose coupling. Mediator pattern falls under behavioral pattern category.
Implementation
我们通过聊天室示例来演示中介者模式，在该聊天室中，多个用户可以向聊天室发送消息，而由聊天室负责向所有用户显示消息。我们创建了两个类 ChatRoom 和 User。User 对象将使用 ChatRoom 方法来共享其消息。
We are demonstrating mediator pattern by example of a chat room where multiple users can send message to chat room and it is the responsibility of chat room to show the messages to all users. We have created two classes ChatRoom and User. User objects will use ChatRoom method to share their messages.
MediatorPatternDemo，我们的演示类，将使用 User 对象来展示它们之间的通信。
MediatorPatternDemo, our demo class, will use User objects to show communication between them.
Step 1
创建中介者类。
Create mediator class.
ChatRoom.java
import java.util.Date;
public class ChatRoom {
public static void showMessage(User user, String message){
System.out.println(new Date().toString() + " [" + user.getName() + "] : " + message);
}
}Step 2
创建用户类
Create user class
User.java
public class User {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public User(String name){
this.name = name;
}
public void sendMessage(String message){
ChatRoom.showMessage(this,message);
}
}Step 3
使用 User 对象来展示它们之间的通信。
Use the User object to show communications between them.
MediatorPatternDemo.java
public class MediatorPatternDemo {
public static void main(String[] args) {
User robert = new User("Robert");
User john = new User("John");
robert.sendMessage("Hi! John!");
john.sendMessage("Hello! Robert!");
}
}