for daily read

import java.util.*; public class VisitorPattern { public static void main(String[] args) { PersonStructure structure = new PersonStructure(); Visitor1 visitor1 = new Visitor1(); System.out.println("访问者1的访问记录："); structure.Accept(visitor1); System.out.println("学生年龄的总和：" + visitor1.getStudentAgeSum() + " 老师年龄的总和：" + visitor1.getTeacherAgeSum()); System.out.println("========================================="); Visitor2 visitor2 = new Visitor2(); System.out.println("访问者2的访问记录："); structure.Accept(visitor2); System.out.println("学生的最高成绩：" + visitor2.getMaxScore() + " 老师的最高工龄：" + visitor2.getMaxWorkYear()); } } interface Visitor { public void visitStudent(Student student); // 访问学生 public void visitTeacher(Teacher teacher); // 访问老师 } class Visitor1 implements Visitor { // 访问者1 分别统计学生和老师的年龄总和 private int studentAgeSum = 0; private int teacherAgeSum = 0; public int getStudentAgeSum() { return studentAgeSum; } public int getTeacherAgeSum() { return teacherAgeSum; } @Override public void visitStudent(Student student) { System.out.println("访问者1访问学生：" + student.getName() + " 年龄：" + student.getAge()); studentAgeSum += student.getAge(); } @Override public void visitTeacher(Teacher teacher) { System.out.println("访问者1访问老师：" + teacher.getName() + " 年龄：" + teacher.getAge()); teacherAgeSum += teacher.getAge(); } } class Visitor2 implements Visitor { // 访问者2 分别求出 学生的最高成绩 以及 老师的最高工龄 private int maxScore = -1; private int maxWorkYear = -1; public int getMaxScore() { return maxScore; } public int getMaxWorkYear() { return maxWorkYear; } @Override public void visitStudent(Student student) { System.out.println("访问者2访问学生：" + student.getName() + " 成绩：" + student.getScore()); maxScore = Math.max(maxScore, student.getScore()); } @Override public void visitTeacher(Teacher teacher) { System.out.println("访问者2访问老师：" + teacher.getName() + " 工龄：" + teacher.getWorkYear()); maxWorkYear = Math.max(maxWorkYear, teacher.getWorkYear()); } } class PersonStructure { private List<Person> personList = new ArrayList<Person>(); public PersonStructure() { personList.add(new Student("张三", 20, 70)); personList.add(new Student("李四", 21, 80)); personList.add(new Student("王五", 22, 90)); personList.add(new Teacher("李老师", 26, 3)); personList.add(new Teacher("陈老师", 27, 4)); personList.add(new Teacher("刘老师", 28, 5)); } public void Accept(Visitor visitor) { // for (遍历对象类型 对象名 : 遍历对象) for (Person person : personList) { person.Accept(visitor); } } } abstract class Person { private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public int getAge() { return age; } public abstract void Accept(Visitor visitor); } class Student extends Person { private int score; public Student(String name, int age, int score) { super(name, age); this.score = score; } public int getScore() { return score; } @Override public void Accept(Visitor visitor) { visitor.visitStudent(this); } } class Teacher extends Person { private int workYear; public Teacher(String name, int age, int workYear) { super(name, age); this.workYear = workYear; } public int getWorkYear() { return workYear; } @Override public void Accept(Visitor visitor) { visitor.visitTeacher(this); } }