背景：

想必獎學金大家都不陌生，在學校裏獎學金往往分為三種班獎學金、院級獎學金以及校級獎學金，但是我們往往苦於政策修改，不知道自己的獎學金該找誰領，於是乎就詢問順序就是：班級輔導員->學院老師->學校老師，我們最多且只能在一個人那到一份獎學金，這就是職責鏈。輔導員處領不到就輔導員就會讓你問問學院老師，學院老師處領不到就會讓你問問學校老師，這互相（推脫）其實就是職責鏈模式。

責任鏈模式圖:

        public interface IStudent {

            int getType();

            String getRequest();
        }
 

        public class Student implements IStudent {
           private int type = 0;

           private String request = "";


           public Student(int type, String request) {
              this.type = type;
              this.request = request;
           }

           public int getType() {
              return this.type;
           }

           public String getRequest() {
              return this.request;
           }
        }
 

        public abstract class Handler {
              public static final Integer CLASS_SCHOLARSHIP = 1;

              public static final Integer COLLEGE_SCHOLARSHIP = 2;

              public static final Integer UNIVERSITY_SCHOLARSHIP = 3;

              //責任處理級別
              private int level = 0;

              //下一位處理者
              private Handler nextHandler;

              public Handler(int level) {
                  this.level = level;
              }

              public void HandleMsg(IStudent student) {
                  if (student.getType() == this.level) {

              }
            }

            public void setNext(Handler handler) {
            this.nextHandler = handler;
          }

             public abstract void response(IStudent student);


        }
        
 

    public class ClassTeacher extends Handler {
    public ClassTeacher() {
        super(Handler.CLASS_SCHOLARSHIP);
    }

    public void response(IStudent student) {
        System.out.println(student.getRequest());
        System.out.println("班級老師批準！");
    }
}

public class CollegeTeacher extends Handler{
    public CollegeTeacher() {
        super(Handler.COLLEGE_SCHOLARSHIP);
    }

    public void response(IStudent student) {
        System.out.println(student.getRequest());
        System.out.println("學院老師批準！");
    }
}

public class UniversityTeacher extends Handler {
    public UniversityTeacher() {
        super(Handler.UNIVERSITY_SCHOLARSHIP);
    }

    public void response(IStudent student) {
        System.out.println(student.getRequest());
        System.out.println("學校老師批準！");
    }
}

責任鏈缺點：
（1）性能問題，每個請求都會從鏈頭遍歷到鏈尾
（2）如果責任塊過多，會導致debug異常困難

使用場景，在字符類型判斷需求中就可以使用該設計模式

設計模式——責任鏈模式