责任链模式

来源：互联网发布：2017最新癌症数据统计编辑：程序博客网时间：2024/06/11 05:43

定义：将能够处理同一类请求的对象连成一条链，所提交的请求沿链传递，能处理的自己处理，不能处理的传递给下一个对象。

场景：java中异常机制try{}catch{}；js中时间的冒泡和捕获机制，java语言中事件采取观察者模式；servlet开发中，过滤器的链处理；struct2拦截器的调用也是典型的责任链模式

例子：比如请假流程，就是一层一层的传递给下一个领导，就是链状结构。

Leader（抽象类）

public abstract class Leader {protected String name;protected Leader nextLeader; //责任链上的后继对象public Leader(String name) {super();this.name = name;}//设定责任链上的后继对象public void setNextLeader(Leader nextLeader) {this.nextLeader = nextLeader;}/** * 处理请求的核心的业务方法 * @param request */public abstract void handleRequest(LeaveRequest request);}

Director.java（主任）

public class Director extends Leader {public Director(String name) {super(name);}@Overridepublic void handleRequest(LeaveRequest request) {if(request.getLeaveDays()<3){System.out.println("员工："+request.getEmpName()+"请假，天数："+request.getLeaveDays()+",理由："+request.getReason());System.out.println("主任："+this.name+",审批通过！");}else{if(this.nextLeader!=null){this.nextLeader.handleRequest(request);}}}}

Manager.java（经理）

public class Manager extends Leader {public Manager(String name) {super(name);}@Overridepublic void handleRequest(LeaveRequest request) {if(request.getLeaveDays()<10){System.out.println("员工："+request.getEmpName()+"请假，天数："+request.getLeaveDays()+",理由："+request.getReason());System.out.println("经理："+this.name+",审批通过！");}else{if(this.nextLeader!=null){this.nextLeader.handleRequest(request);}}}}

ViceGeneralMannager.java（副总经理）

public class ViceGeneralManager extends Leader {public ViceGeneralManager(String name) {super(name);}@Overridepublic void handleRequest(LeaveRequest request) {if(request.getLeaveDays()<20){System.out.println("员工："+request.getEmpName()+"请假，天数："+request.getLeaveDays()+",理由："+request.getReason());System.out.println("副总经理："+this.name+",审批通过！");}else{if(this.nextLeader!=null){this.nextLeader.handleRequest(request);}}}}

GeneraManager.java（总经理）

public class GeneralManager extends Leader {public GeneralManager(String name) {super(name);}@Overridepublic void handleRequest(LeaveRequest request) {if(request.getLeaveDays()<30){System.out.println("员工："+request.getEmpName()+"请假，天数："+request.getLeaveDays()+",理由："+request.getReason());System.out.println("总经理："+this.name+",审批通过！");}else{System.out.println("莫非"+request.getEmpName()+"想辞职，居然请假"+request.getLeaveDays()+"天！");}}}

LeaveRequest.java（请假消息）

public class LeaveRequest {private String empName;private int leaveDays;private String reason;public LeaveRequest(String empName, int leaveDays, String reason) {super();this.empName = empName;this.leaveDays = leaveDays;this.reason = reason;}public String getEmpName() {return empName;}public void setEmpName(String empName) {this.empName = empName;}public int getLeaveDays() {return leaveDays;}public void setLeaveDays(int leaveDays) {this.leaveDays = leaveDays;}public String getReason() {return reason;}public void setReason(String reason) {this.reason = reason;} }

测试

public class Client {public static void main(String[] args) {Leader a = new Director("张三");Leader b = new Manager("李四");Leader b2 = new ViceGeneralManager("李小四");Leader c = new GeneralManager("王五");//组织责任链对象的关系a.setNextLeader(b);b.setNextLeader(b2);b2.setNextLeader(c);//开始请假操作LeaveRequest req1 = new LeaveRequest("TOM", 15, "回英国老家探亲！");a.handleRequest(req1);}}

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