Design Patterns GOF23 chain of responsibility pattern

Chain of Responsibility pattern chain of responsibility

Object request can process the same type connected into a chain, sequentially transmitting the request submitted in the chain, until it is transmitted to the ability to process the requested object, it can not pass down a chain

Scenes:

- playing cards

- Scholarships for approval

- Leave Approval

Core: it is chained in the client, the array may be loaded in the configuration file or by the presence of

Develop common scenarios:

- the try the catch abnormal chain

-javascript language, bubbling and event capture mechanism of the Java language, an event handler using the Observer pattern

-Servlet development, the filter chaining

-Struts2, call interceptor is typical of chaining

Examples : work leave

Director approval manager for approval 0-3 3-10 10-30 General Manager for approval

/ **
 * written request for leave
 * @author sail knock Code
 *
 * /

public class LeaveRequest {
   private String empName;
   private int leaveDays;
   private String 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;
   }
   public LeaveRequest(String empName, int leaveDays, String reason) {
    this.empName = empName;
    this.leaveDays = leaveDays;
    this.reason = reason;
   }
}

public abstract class Leader {
  protected String leaderName;
  protected Leader nextLeader; // successor objects responsibility chain
  public Leader (String leaderName) {
   this.leaderName = leaderName;
  }
  leading disposed at a //
  public void setNetLeader (Leader leader) {
   Leader = this.nextLeader;
  }
   // business method for processing leave requests
  public abstract void Handler (LeaveRequest leaveRequest);
}

public class Director extends Leader{

 public Director(String leaderName) {
  super(leaderName);
 }

 @Override
 public void Handler (LeaveRequest leaveRequest) {
     IF ( leaveRequest.getLeaveDays () <. 3) {
     System.out.println ( "Employees:" + leaveRequest.getEmpName () + " , leave:" + leaveRequest.getLeaveDays () + "reason:" + leaveRequest.getReason ());
     System.out.println ( "Director:" + this.leaderName + "!, approval");
    } the else {
     ! IF (this.nextLeader = null) {
      nextLeader. Handler (leaveRequest);
     } the else {
      System.out.println ( "this staff may want to quit");
     }
    }
 }

}

public class Manager extends Leader{

 public Manager(String leaderName) {
  super(leaderName);
 }

 @Override
 public void Handler (LeaveRequest leaveRequest) {
    IF (leaveRequest.getLeaveDays () <10) {
     System.out.println ( "Employees:" + leaveRequest.getEmpName () + " , leave:" + leaveRequest.getLeaveDays () + "reason:" + leaveRequest.getReason ());
     System.out.println ( "manager:" + this.leaderName + "!, approval");
    } the else {
     ! IF (this.nextLeader = null) {
      nextLeader. Handler (leaveRequest);
     } the else {
      System.out.println ( "this staff may want to quit");
     }
    }
 }

}

public class GeneralManager extends Leader{

 public GeneralManager(String leaderName) {
  super(leaderName);
 }

 @Override
 public void Handler (LeaveRequest leaveRequest) {
    IF (leaveRequest.getLeaveDays () <30) {
     System.out.println ( "Employees:" + leaveRequest.getEmpName () + " , leave:" + leaveRequest.getLeaveDays () + "reason:" + leaveRequest.getReason ());
     System.out.println ( "general manager:" + this.leaderName + "!, approval");
    } the else {
     ! IF (this.nextLeader = null) {
      nextLeader .handler (leaveRequest);
     } the else {
      System.out.println ( "this staff may want to quit");
     }
    }
 }

}

public class Client {

 static void main public (String [] args) {
   Leader A new new Director = ( "John Doe");
   Leader B = new new Manager ( "John Doe");
   Leader include GeneralManager new new C = ( "Wang Wu");
   
    // Start chain of responsibility tissue
   a.setNetLeader (B);
   b.setNetLeader (C);
   
   LeaveRequest REQl new new LeaveRequest = ( "TOM", 2, "grasping JACK");
   a.handler (REQl);
 }

}