项目的BUG（问神篇）-02

这周项目写创建内容接口时出现一个问题，我输出的数据怎么都变了？

过程是这样的，有一个接口可查到目前所有数据，返回的那叫一个全，然后我就调用后复制呗，那不能一个一个复制吧，就调用了BeanUtils.copyProperties().我以为这就万事大吉了，然后就测试呗，结果却和我想要的不一样，我就想这咋回事，排查后发现问题出在了我的对象身上，因为我的实例对象里有引用类型的，后来我给他改了，就出现问题了。

我来给大家验证一下过程：

Student类

public class Student {
    private String name;
    private Integer age;

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + ''' +
                ", age='" + age + ''' +
                '}';
    }

    public String getName() {
        return name;
    }

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

Teacher类，里边有一个Student引用类型

public class Teacher {
    private String tName;
    private Integer tAge;

    private Student student;

    @Override
    public String toString() {
        return "Teacher{" +
                "tName='" + tName + ''' +
                ", tAge=" + tAge +
                ", student=" + student +
                '}';
    }

    public Student getStudent() {
        return student;
    }

    public void setStudent(Student student) {
        this.student = student;
    }

    public String gettName() {
        return tName;
    }

    public void settName(String tName) {
        this.tName = tName;
    }

    public Integer gettAge() {
        return tAge;
    }

    public void settAge(Integer tAge) {
        this.tAge = tAge;
    }

}

客户端类

import org.springframework.beans.BeanUtils;

public class Client {
    public static void main(String[] args) {
        Teacher teacher = new Teacher();
        Teacher teacher1 = new Teacher();
        Student student = new Student();
        teacher.settName("老师");
        teacher.settAge(23);
        teacher.setStudent(student);
        student.setAge(10);
        student.setName("赵高");
        System.out.println(teacher.toString());
        System.out.println(teacher1.toString());

        System.err.println("==================================");
        BeanUtils.copyProperties(teacher, teacher1);
        System.out.println(teacher.toString());
        System.out.println(teacher1.toString());


        System.err.println("==================================");
        teacher1.getStudent().setName("王麻子");
        System.out.println("深复制or浅复制" + teacher.toString());
        System.out.println("深复制or浅复制" + teacher1.toString());
    }
}

输出如下:

Teacher{tName='老师', tAge=23, student=Student{name='赵高', age='10'}}
Teacher{tName='null', tAge=null, student=null}
==================================
Teacher{tName='老师', tAge=23, student=Student{name='赵高', age='10'}}
Teacher{tName='老师', tAge=23, student=Student{name='赵高', age='10'}}
==================================
深复制or浅复制Teacher{tName='老师', tAge=23, student=Student{name='王麻子', age='10'}}
深复制or浅复制Teacher{tName='老师', tAge=23, student=Student{name='王麻子', age='10'}}

引用改了，那么之前那个示例对象的引用也改了，所以这是浅复制，做个笔记，以后要谨记