Java注解与反射（三）

package refection ;
 import java.util.Objects;
 // 反射
 public class Test {
     @SuppressWarnings("all")
     public static void main(String[] args) throws ClassNotFoundException {
         // 创建对象，实际上时需要泛型的，但是没有，用不到，直接去掉。  看着难受就强行镇压黄色的提示
       Class c1 = Class.forName("refection.User");
       // 一个类在内存中只有一个Class对象，可以进行验证
         // 验证的方式：多次获取，看哈希码是否相同
         // 一个类被加载之后，类的整个结构都会被封装在Class对象中
         Class c2 = Class.forName("refection.User");
         Class c3 = Class.forName("refection.User");
         Class c4 = Class.forName("refection.User");
         System.out.println(c2.hashCode());
         System.out.println(c3.hashCode());
         System.out.println(c4.hashCode());
     }
 }
 // 实体类：pojo、entity类
 class User{
     private String name  ;
     private int id ;
     private int age ;
     public User() {
     }
     public User(String name, int id, int age) {
         this.name = name;
         this.id = id;
         this.age = age;
     }
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     public int getAge() {
         return age;
     }
     public void setAge(int age) {
         this.age = age;
     }
     @Override
     public String toString() {
         return "User{" +
                 "name='" + name + ''' +
                 ", id=" + id +
                 ", age=" + age +
                 '}';
     }
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         User user = (User) o;
         return id == user.id &&
                 age == user.age &&
                 Objects.equals(name, user.name);
     }
     @Override
     public int hashCode() {
         return Objects.hash(name, id, age);
     }
 }

package refection ;
 import java.util.Objects;
 public class Test02 {
     @SuppressWarnings("all")
     public static void main(String[] args) throws ClassNotFoundException {
         Person person = new Student();
         System.out.println("这个人是" + person.name);
        //  - 方式一：通过对象获得
         Class c1 = person.getClass();
         System.out.println(c1.hashCode());
        //  - 方式二：通过反射forName获得
         Class c2 = Class.forName("refection.Student");
         System.out.println(c2.hashCode());
        //  - 方式三：通过类名.class获得
        Class c3 = Student.class ;
         System.out.println(c3.hashCode());
         // 方式四：通过内置类型的包装类都有一个Type属性
         Class c4 = Integer.TYPE ;
         System.out.println(c4);
         System.out.println(c4.hashCode());
         // 获取父类型
         Class c5 = c1.getSuperclass();
         System.out.println(c5);
     }
 }
 class Person {
     public String name ;
     public Person (){
     }
     public Person(String name){
         this.name = name ;
     }
     @Override
     public String toString() {
         return "Person{" +
                 "name='" + name + ''' +
                 '}';
     }
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         Person person = (Person) o;
         return Objects.equals(name, person.name);
     }
     @Override
     public int hashCode() {
         return Objects.hash(name);
     }
 }
 class Student extends Person{
     public Student(){
         this.name = "学生" ;
     }
 }
 class Teacher extends Person{
     public Teacher(){
         this.name = "教师" ;
     }
 }