反射修改原型模式中未深克隆的String类型属性

结论：
1、直接赋值的方式，对原型模式中未深克隆的String类型属性无影响
2、反射修改原型模式中未深克隆的String类型属性，未重新赋值的所有实例中String类型属性也会发生变化；从安全的角度考虑，有被恶意破坏的风险

源码如下：

原型类

class User implements Cloneable {
  private String name = "zahngsan";

  @Override
  protected Object clone() throws CloneNotSupportedException {
    return super.clone();
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  @Override
  public String toString() {
    return "User{" + "name='" + name + '\'' + '}';
  }
}

测试类

import java.lang.reflect.Field;

public class Main {

  public static void main(String[] args)
      throws CloneNotSupportedException, NoSuchFieldException, IllegalAccessException {
    set();
    System.out.println("========================");
    fanshe();
  }

  // 直接赋值的方式，对原型模式中未深克隆的String类型属性无影响
  private static void set() throws CloneNotSupportedException {
    User user1 = new User();
    User user2 = (User) user1.clone();
    User user3 = (User) user1.clone();
    user3.setName("lisi");
    User user4 = (User) user1.clone();
    System.out.println(user1); // User{name='zahngsan'}
    System.out.println(user2); // User{name='zahngsan'}
    System.out.println(user3); // User{name='lisi'}
    System.out.println(user4); // User{name='zahngsan'}
    System.out.println(user1.getName() == user2.getName()); // true
    System.out.println(user1.getName() == user3.getName()); // false
    System.out.println(user1.getName() == user4.getName()); // true
  }

  // 使用反射修改原型模式中未深克隆的String类型属性，未重新赋值的所有实例中String类型属性也会发生变化；从安全的角度考虑，有被恶意破坏的风险
  private static void fanshe() throws CloneNotSupportedException, NoSuchFieldException, IllegalAccessException {
    User user1 = new User();
    User user2 = (User) user1.clone();
    User user3 = (User) user1.clone();
    String name = user3.getName();
    Field value = name.getClass().getDeclaredField("value");
    value.setAccessible(true);
    value.set(name, new char[]{'l', 'i', 's', 'i'});
    User user4 = (User) user1.clone();
    System.out.println(user1); // User{name='lisi'}
    System.out.println(user2); // User{name='lisi'}
    System.out.println(user3); // User{name='lisi'}
    System.out.println(user4); // User{name='lisi'}
    System.out.println(user1.getName() == user2.getName()); // true
    System.out.println(user1.getName() == user3.getName()); // true
    System.out.println(user1.getName() == user4.getName()); // true
  }
}