JAVA开发的23种设计模式之 --- 中介者模式

中介者模式

概述 : 用一个中介对象来封装一系列的对象交互.中介者使各对象不需要显式的相互引用,从而使其耦合松散,而且可以独立地改变他们之间的交互
中介者模式所包含的角色
Mediator : 中介者角色.在里面定义各个部门之间的交互对象,
ConcreteMediator :
具体中介者实现角色.维护各个部门之间的交互关系
Deparement :
部门角色.所有具体部门类的父类.
ConreteDepaerment :
具体部门角色.实现与中介者角色的交互.从而实现与其他部门的交互

使用场景
系统中对象之间存在比较复杂的引用关系,导致他们之间的依赖关系结构混乱而已难以复用
想通过一个中间类来封装多个类中的行为,而又不想生成太多的子类

优点
降低了类的复杂度,将一对多的关系转化成了一对一(具体部门角色对中介者)
各个类之间实现解耦
符合迪米特原则

缺点
如果部门很多的话,中介类会非常庞大,难以维护

代码实现
        示例:一个公司,各个部门之间可能需要经常交互,这样非常的错综复杂.现在使用中介者模式来简单实现产品部门和研发部门的交互.现在产品部门通常要时刻了解研发部门的开发进度,所以两个部门需要经常进行联系.

   
抽象中介者角色 

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public abstract class Mediator {
public abstract void contact(Department department,String message);
}

具体中介者角色

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public class ConcreteMediator extends Mediator {
protected ResearchDepartment researchDepartment;
protected ProductDepartment productDepartment;

public ResearchDepartment getResearchDepartment() {
return researchDepartment;
}

public void setResearchDepartment(ResearchDepartment researchDepartment) {
this.researchDepartment = researchDepartment;
}

public ProductDepartment getProductDepartment() {
return productDepartment;
}

public void setProductDepartment(ProductDepartment productDepartment) {
this.productDepartment = productDepartment;
}

@Override
public void contact(Department department, String message) {
if ("研发部".equals(department.getName())) {
productDepartment.getMessage(message);
} else if ("产品部".equals(department.getName())) {
researchDepartment.getMessage(message);
}
}
}

部门角色类

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public abstract class Department {
private String name;
protected Mediator mediator;

public Department(String name, Mediator mediator){
this.name = name;
this.mediator = mediator;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

//接收其他部门的消息
public abstract void getMessage(String message);

}

具体部门角色1(产品部)

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public class ProductDepartment extends Department {
public ProductDepartment(String name, Mediator mediator) {
super(name, mediator);
}

//接收其他部门的消息
@Override
public void getMessage(String message) {
System.out.println("产品部刚刚收到消息 : "+message);
}

//向其他部门发送信息
public void sendMessage(ProductDepartment productDepartment,String message) {
mediator.contact(productDepartment,message);
}

}

具体部门角色2(研发部)

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public class ResearchDepartment extends Department {
public ResearchDepartment(String name, Mediator mediator) {
super(name, mediator);
}

//接受其他部门的消息
@Override
public void getMessage(String message) {
System.out.println("研发部刚刚收到消息 : "+message);
}

//向其他部门发送消息
public void sendMessage(ResearchDepartment researchDepartment, String message) {
mediator.contact(researchDepartment,message);
}

}

测试类

package Mediator;

/**
* Created by looper on 2017/8/28.
*/
public class MediatorTest {
public static void main(String[] args) {
ConcreteMediator mediator = new ConcreteMediator();

ProductDepartment productDepartment = new ProductDepartment("产品部",mediator);
ResearchDepartment researchDepartment = new ResearchDepartment("研发部",mediator);

mediator.setProductDepartment(productDepartment);
mediator.setResearchDepartment(researchDepartment);

productDepartment.sendMessage(productDepartment,"我是产品部,需要研发部提供具体的开发日程");
researchDepartment.sendMessage(researchDepartment,"我的研发部,最新的开发日程已经发送到你们,请注意查收");
}
}

我将23种设计模式的代码上传到CSDN,有用得到的同学 可以去下载.

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