中介者模式（设计模式详解版）-mile米乐体育

模式的定义与特点

1. 类之间各司其职，符合迪米特法则。
2. 降低了对象之间的耦合性，使得对象易于独立地被复用。
3. 将对象间的一对多关联转变为一对一的关联，提高系统的灵活性，使得系统易于维护和扩展。

模式的结构与实现

1. 模式的结构

1. 抽象中介者（mediator）角色：它是中介者的接口，提供了同事对象注册与转发同事对象信息的抽象方法。
2. 具体中介者（concrete mediator）角色：实现中介者接口，定义一个 list 来管理同事对象，协调各个同事角色之间的交互关系，因此它依赖于同事角色。
3. 抽象同事类（colleague）角色：定义同事类的接口，保存中介者对象，提供同事对象交互的抽象方法，实现所有相互影响的同事类的公共功能。
4. 具体同事类（concrete colleague）角色：是抽象同事类的实现者，当需要与其他同事对象交互时，由中介者对象负责后续的交互。

2. 模式的实现

 package net.biancheng.c.mediator;  import java.util.*;  public class mediatorpattern {     public static void main(string[] args) {         mediator md = new concretemediator();         colleague c1, c2;         c1 = new concretecolleague1();         c2 = new concretecolleague2();         md.register(c1);         md.register(c2);         c1.send();         system.out.println("-------------");         c2.send();     } }  //抽象中介者 abstract class mediator {     public abstract void register(colleague colleague);      public abstract void relay(colleague cl); //转发 }  //具体中介者 class concretemediator extends mediator {     private list colleagues = new arraylist();      public void register(colleague colleague) {         if (!colleagues.contains(colleague)) {             colleagues.add(colleague);             colleague.setmedium(this);         }     }      public void relay(colleague cl) {         for (colleague ob : colleagues) {             if (!ob.equals(cl)) {                 ((colleague) ob).receive();             }         }     } }  //抽象同事类 abstract class colleague {     protected mediator mediator;      public void setmedium(mediator mediator) {         this.mediator = mediator;     }      public abstract void receive();      public abstract void send(); }  //具体同事类 class concretecolleague1 extends colleague {     public void receive() {         system.out.println("具体同事类1收到请求。");     }      public void send() {         system.out.println("具体同事类1发出请求。");         mediator.relay(this); //请中介者转发     } }  //具体同事类 class concretecolleague2 extends colleague {     public void receive() {         system.out.println("具体同事类2收到请求。");     }      public void send() {         system.out.println("具体同事类2发出请求。");         mediator.relay(this); //请中介者转发     } }

 具体同事类1发出请求。 具体同事类2收到请求。 ------------- 具体同事类2发出请求。 具体同事类1收到请求。

模式的应用实例

 package net.biancheng.c.mediator;  import javax.swing.*; import java.awt.*; import java.awt.event.actionevent; import java.awt.event.actionlistener; import java.util.arraylist; import java.util.list;  public class datingplatform {     public static void main(string[] args) {         medium md = new estatemedium();    //房产中介         customer member1, member2;         member1 = new seller("张三(卖方)");         member2 = new buyer("李四(买方)");         md.register(member1); //客户注册         md.register(member2);     } }  //抽象中介者：中介公司 interface medium {     void register(customer member); //客户注册      void relay(string from, string ad); //转发 }  //具体中介者：房地产中介 class estatemedium implements medium {     private list members = new arraylist();      public void register(customer member) {         if (!members.contains(member)) {             members.add(member);             member.setmedium(this);         }     }      public void relay(string from, string ad) {         for (customer ob : members) {             string name = ob.getname();             if (!name.equals(from)) {                 ((customer) ob).receive(from, ad);             }         }     } }  //抽象同事类：客户 abstract class customer extends jframe implements actionlistener {     private static final long serialversionuid = -7219939540794786080l;     protected medium medium;     protected string name;     jtextfield senttext;     jtextarea receivearea;      public customer(string name) {         super(name);         this.name = name;     }      void clientwindow(int x, int y) {         container cp;         jscrollpane sp;         jpanel p1, p2;         cp = this.getcontentpane();         senttext = new jtextfield(18);         receivearea = new jtextarea(10, 18);         receivearea.seteditable(false);         p1 = new jpanel();         p1.setborder(borderfactory.createtitledborder("接收内容："));         p1.add(receivearea);         sp = new jscrollpane(p1);         cp.add(sp, borderlayout.north);         p2 = new jpanel();         p2.setborder(borderfactory.createtitledborder("发送内容："));         p2.add(senttext);         cp.add(p2, borderlayout.south);         senttext.addactionlistener(this);         this.setlocation(x, y);         this.setsize(250, 330);         this.setresizable(false); //窗口大小不可调整         this.setdefaultcloseoperation(jframe.exit_on_close);         this.setvisible(true);     }      public void actionperformed(actionevent e) {         string tempinfo = senttext.gettext().trim();         senttext.settext("");         this.send(tempinfo);     }      public string getname() {         return name;     }      public void setmedium(medium medium) {         this.medium = medium;     }      public abstract void send(string ad);      public abstract void receive(string from, string ad); }  //具体同事类：卖方 class seller extends customer {     private static final long serialversionuid = -1443076716629516027l;      public seller(string name) {         super(name);         clientwindow(50, 100);     }      public void send(string ad) {         receivearea.append("我(卖方)说: "   ad   "\n");         //使滚动条滚动到最底端         receivearea.setcaretposition(receivearea.gettext().length());         medium.relay(name, ad);     }      public void receive(string from, string ad) {         receivearea.append(from   "说: "   ad   "\n");         //使滚动条滚动到最底端         receivearea.setcaretposition(receivearea.gettext().length());     } }  //具体同事类：买方 class buyer extends customer {     private static final long serialversionuid = -474879276076308825l;      public buyer(string name) {         super(name);         clientwindow(350, 100);     }      public void send(string ad) {         receivearea.append("我(买方)说: "   ad   "\n");         //使滚动条滚动到最底端         receivearea.setcaretposition(receivearea.gettext().length());         medium.relay(name, ad);     }      public void receive(string from, string ad) {         receivearea.append(from   "说: "   ad   "\n");         //使滚动条滚动到最底端         receivearea.setcaretposition(receivearea.gettext().length());     } }

模式的应用场景

• 当对象之间存在复杂的网状结构关系而导致依赖关系混乱且难以复用时。
• 当想创建一个运行于多个类之间的对象，又不想生成新的子类时。

模式的扩展

1. 不定义中介者接口，把具体中介者对象实现成为单例。
2. 同事对象不持有中介者，而是在需要的时候直接获取中介者对象并调用。

 package net.biancheng.c.mediator;  import java.util.*;  public class simplemediatorpattern {     public static void main(string[] args) {         simplecolleague c1, c2;         c1 = new simpleconcretecolleague1();         c2 = new simpleconcretecolleague2();         c1.send();         system.out.println("-----------------");         c2.send();     } }  //简单单例中介者 class simplemediator {     private static simplemediator smd = new simplemediator();     private list colleagues = new arraylist();      private simplemediator() {     }      public static simplemediator getmedium() {         return (smd);     }      public void register(simplecolleague colleague) {         if (!colleagues.contains(colleague)) {             colleagues.add(colleague);         }     }      public void relay(simplecolleague scl) {         for (simplecolleague ob : colleagues) {             if (!ob.equals(scl)) {                 ((simplecolleague) ob).receive();             }         }     } }  //抽象同事类 interface simplecolleague {     void receive();      void send(); }  //具体同事类 class simpleconcretecolleague1 implements simplecolleague {     simpleconcretecolleague1() {         simplemediator smd = simplemediator.getmedium();         smd.register(this);     }      public void receive() {         system.out.println("具体同事类1：收到请求。");     }      public void send() {         simplemediator smd = simplemediator.getmedium();         system.out.println("具体同事类1：发出请求...");         smd.relay(this); //请中介者转发     } }  //具体同事类 class simpleconcretecolleague2 implements simplecolleague {     simpleconcretecolleague2() {         simplemediator smd = simplemediator.getmedium();         smd.register(this);     }      public void receive() {         system.out.println("具体同事类2：收到请求。");     }      public void send() {         simplemediator smd = simplemediator.getmedium();         system.out.println("具体同事类2：发出请求...");         smd.relay(this); //请中介者转发     } }

 具体同事类1：发出请求... 具体同事类2：收到请求。 ----------------- 具体同事类2：发出请求... 具体同事类1：收到请求。