BeanUtils. Copyproperties() and jsonobject What copy type is parseobject() (shallow copy or deep copy)

One 、 Conclusion

• BeanUtils.copyProperties()： Shallow copy
• JSONObject.parseObject()： Deep copy

Two 、 prove BeanUtils.copyProperties() Is a shallow copy

Code ：

import org.springframework.beans.BeanUtils;

public class Test {
    
    public static void main(String[] args) throws Exception {
    
        Info info1 = new Info();
        Student student = new Student();
        student.setName(" Li Hua ");
        student.setAge(18);
        info1.setCountry(" China ");
        info1.setStudent(student);

        Info info2 = new Info();
        BeanUtils.copyProperties(info1, info2);
        info2.setCountry("American");
        info2.getStudent().setName("Tom");
        info2.getStudent().setAge(18);

        System.out.println(info1);
        System.out.println(info2);
    }
}

class Info {
    

    /**  National Information  **/
    private String country;

    /**  Basic information of students  **/
    private Student student;

    public Student getStudent() {
    
        return student;
    }

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

    public String getCountry() {
    
        return country;
    }

    public void setCountry(String country) {
    
        this.country = country;
    }

    @Override
    public String toString() {
    
        return "Info{" +
                "country='" + country + '\'' +
                ", student=" + student +
                '}';
    }
}

/** *  Reference data type  */
class Student {
    

    /**  full name  **/
    private String name;

    /**  Age  **/
    private Integer 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;
    }

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

result ：

Info{
    country=' China ', student=Student{
    name='Tom', age=18}}
Info{
    country='American', student=Student{
    name='Tom', age=18}}

explain ：

You can see from the results student All are Tom, It means it's a shallow copy

expand ：

Don't know much about BeanUtils.copyProperties() Please see BeanUtils.copyProperties(A, B) Use

3、 ... and 、 prove JSONObject.parseObject() It's a deep copy

Code ：

class Test {
    
    public static void main(String[] args) throws Exception {
    
        Info info1 = new Info();
        Student student = new Student();
        student.setName(" Li Hua ");
        student.setAge(18);
        info1.setCountry(" China ");
        info1.setStudent(student);

        Info info2 = JSONObject.parseObject(JSONObject.toJSONString(info1), new TypeReference<Info>(){
    });
        info2.setCountry("American");
        info2.getStudent().setName("Tom");
        info2.getStudent().setAge(18);

        System.out.println(info1);
        System.out.println(info2);
    }
}

class Info {
    

    /**  National Information  **/
    private String country;

    /**  Basic information of students  **/
    private Student student;

    public Student getStudent() {
    
        return student;
    }

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

    public String getCountry() {
    
        return country;
    }

    public void setCountry(String country) {
    
        this.country = country;
    }

    @Override
    public String toString() {
    
        return "Info{" +
                "country='" + country + '\'' +
                ", student=" + student +
                '}';
    }
}

/** *  Reference data type  */
class Student {
    

    /**  full name  **/
    private String name;

    /**  Age  **/
    private Integer 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;
    }

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

result ：

Info{
    country=' China ', student=Student{
    name=' Li Hua ', age=18}}
Info{
    country='American', student=Student{
    name='Tom', age=18}}

explain ：

You can see from the results student The name of the object is different , The description is a deep copy

Four 、 summary

In the example Info Classes and properties Student Classes do not implement Cloneable Interface , No rewriting clone() Method , It doesn't make sense to say that they are shallow copies or deep copies , But the truth is similar , If you want to understand what is shallow copy , What is deep copy , Please watch Reference copy 、 Shallow copy 、 Deep copy