职责链模式-白红宇

《大话设计模式》阅读笔记和总结。原书是C#编写的，本人用Java实现了一遍，包括每种设计模式的UML图实现和示例代码实现。
目录：
Github地址：

说明

定义：职责链模式（Chain of Responsibility），使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这个对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。

UML图：

职责链模式UML图.png

代码实现：

Handler类，定义一个处理请示的接口

abstract class Handler{    protected Handler successor;    public void setSuccessor(Handler successor) {        this.successor = successor;    }        // 处理请求的抽象方法    public abstract void HandlerRequest(int request);}

ConcreteHandler类，具体处理者类，处理它所负责的请求，可访问它的后继者，如果可处理该请求，就处理之，否则就将该请求转发给它的后继者

/** * ConcreteHandler1，请求数在0和10之间则有权处理，否则转到下一位 */class ConcreteHandler1 extends Handler{    @Override    public void HandlerRequest(int request) {        if (request >= 0 && request < 10) {            System.out.println("ConcreteHandler1处理请求"+request);        }else if(successor !=null){            successor.HandlerRequest(request);        }            }    }/** *  ConcreteHandler2，请求数在10和20之间则有权处理，否则转到下一位 */class ConcreteHandler2 extends Handler{    @Override    public void HandlerRequest(int request) {        if (request >= 10 && request < 20) {            System.out.println("ConcreteHandler2处理请求"+request);        }else if(successor !=null){            successor.HandlerRequest(request);        }            }    }/** *  ConcreteHandler3，请求数在20和30之间则有权处理，否则转到下一位 */class ConcreteHandler3 extends Handler{    @Override    public void HandlerRequest(int request) {        if (request >= 20 && request < 30) {            System.out.println("ConcreteHandler3处理请求"+request);        }else if(successor !=null){            successor.HandlerRequest(request);        }            }    }

客户端代码

public class ChainOfResponsibilityPattern {        public static void main(String[] args) {        Handler h1 = new ConcreteHandler1();        Handler h2 = new ConcreteHandler2();        Handler h3 = new ConcreteHandler3();                h1.setSuccessor(h2);        h2.setSuccessor(h3);                int[] requests = {2,5,14,22,18,3,27,20};        for (int i = 0; i < requests.length; i++) {            h1.HandlerRequest(requests[i]);        }    }}

运行结果

ConcreteHandler1处理请求2ConcreteHandler1处理请求5ConcreteHandler2处理请求14ConcreteHandler3处理请求22ConcreteHandler2处理请求18ConcreteHandler1处理请求3ConcreteHandler3处理请求27ConcreteHandler3处理请求20

示例

例子：在公司无论办什么事情都要走流程，一级一级审批。如果我们想请假，两天以内部门经理就可以批准，如果超过两天，五天以内总监有权限批准，五天以上就需要总经理批准了。如果我们想加薪就只能总经理审批。用程序模拟这个过程。

UML图：

职责链模式示例UML图.png

代码实现：

申请

public class Request {    // 申请类别    private String requestType;    // 申请内容    private String requestContent;    // 申请数量    private int number;    public String getRequestType() {        return requestType;    }    public void setRequestType(String requestType) {        this.requestType = requestType;    }    public String getRequestContent() {        return requestContent;    }    public void setRequestContent(String requestContent) {        this.requestContent = requestContent;    }    public int getNumber() {        return number;    }    public void setNumber(int number) {        this.number = number;    }    }

管理者

public abstract class Manager {    protected String name;    //管理者的上级    protected Manager superior;    public Manager(String name){        this.name = name;    }        public void setSuperior(Manager superior) {        this.superior = superior;    }        public abstract void RequestApplicatios(Request request);}

总经理类

public class CommonManager extends Manager{    public CommonManager(String name) {        super(name);    }    @Override    public void RequestApplicatios(Request request) {        // 经理的权限就是可准许下两天以内的假期        if(request.getRequestType().equals("请假") && request.getNumber()<=2){            System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");        }        // 其余的申请都需转到上级        else{            if(superior!=null){                superior.RequestApplicatios(request);            }        }    }}

总监类

public class Majordomo extends Manager{    public Majordomo(String name) {        super(name);    }    @Override    public void RequestApplicatios(Request request) {        // 经理的权限就是可准许下属一周以内的假期        if(request.getRequestType().equals("请假") && request.getNumber()<=5){            System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");        }        // 其余的申请都需转到上级        else{            if(superior!=null){                superior.RequestApplicatios(request);            }        }    }}

总经理类，可以处理全部任何事情

public class GeneralManager extends Manager{    public GeneralManager(String name) {        super(name);    }    @Override    public void RequestApplicatios(Request request) {        if(request.getRequestType().equals("请假")){            System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");        }        else if(request.getRequestType().equals("加薪") && request.getNumber() <= 500){            System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"被批准");        }        else if(request.getRequestType().equals("加薪") && request.getNumber() > 500){            System.out.println(name+":"+request.getRequestContent()+" 数量"+request.getNumber()+"再说吧");        }    }}

客户端代码

public class Main {        public static void main(String[] args) {        CommonManager jingli = new CommonManager("经理");        Majordomo zongjian = new Majordomo("总监");        GeneralManager zongjingli = new GeneralManager("总经理");        jingli.setSuperior(zongjian);        zongjian.setSuperior(zongjingli);                Request request = new Request();        request.setRequestType("请假");        request.setRequestContent("小菜请假");        request.setNumber(1);        jingli.RequestApplicatios(request);                Request request2 = new Request();        request2.setRequestType("请假");        request2.setRequestContent("小菜请假");        request2.setNumber(4);        jingli.RequestApplicatios(request2);                Request request3 = new Request();        request3.setRequestType("加薪");        request3.setRequestContent("小菜请求加薪");        request3.setNumber(500);        jingli.RequestApplicatios(request3);                Request request4 = new Request();        request4.setRequestType("加薪");        request4.setRequestContent("小菜请求加薪");        request4.setNumber(1000);        jingli.RequestApplicatios(request4);    }}

运行结果

经理:小菜请假 数量1被批准总监:小菜请假 数量4被批准总经理:小菜请求加薪 数量500被批准总经理:小菜请求加薪 数量1000再说吧