添加到Java Spring类中的元素列表中

Question

我有一个帐户类，用于我正在构建的求职应用程序，其中包含教育实例的链接列表（只是大学名称，gpa等）。我想要一个HTTP Post请求来向列表中添加一个元素：

@PostMapping("/education/{id}")
    void newAccount(@RequestBody Education newEducation, @PathVariable Long id) {
        Account a = repository.findById(id).orElseThrow(() -> new AccountNotFoundException(id));
        a.addEducation(newEducation);
    }

这是account类：

import java.util.LinkedList;
import java.util.Objects;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Account {
    private @Id @GeneratedValue Long id;
    private String name;
    private String email;
    private String phone;
    private LinkedList<Education> education;
    Account() {}
    Account(String name, String email, String phone) {
        education = new LinkedList<>();
        this.setName(name);
        this.setEmail(email);
        this.setPhone(phone);
    }
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id=id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    public LinkedList<Education> getEducation() {
        return education;
    }
    public void addEducation(Education e) {
        education.add(e);
    }
    @Override
    public boolean equals(Object o) {
        if (this==o)
            return true;
        if (!(o instanceof Account))
            return false;
        Account acc = (Account)o;
        return name.equals(acc.name);
    }
    @Override
    public int hashCode() {
        return Objects.hash(this.id, this.name);
    }
    @Override
    public String toString() {
        String edu="";
        if (!this.education.isEmpty())
        {
            edu+=", \"Education: [";
            for (Education e: this.education)
            {
                edu+=e.toString();
            }
            edu+="]";
        }
        String s = "Account{";
        
        s += String.format("\"id\": \"%s\", ", this.id);
        s += String.format("\"name\": \"%s\", ", this.name);
        s += String.format("\"email\": \"%s\", ", this.email);
        s += String.format("\"phone\": \"%s\"", this.phone);
        s += edu;
        
        s += "}";
        return s;
    }
}

然而，当我实际发送带有教育数据的post请求时（针对一个已经存在的用户），它并不发布。它确实正确地打印了帐户a（添加了教育），但实际上并不更新数据库。

此外,这是我拥有的另一个类：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class LoadDatabase {
    private static final Logger log = 
            LoggerFactory.getLogger(LoadDatabase.class);
    
    @Bean
    CommandLineRunner initDatabase(AccountRepository repository) {
        return args -> {
            log.info("Preloading " + repository.save(new Account("Alex", "[e-mail]", "214")));
            Account a= new Account("Bob", "[e-mail]", "972");
            //a.addEducation(new Education("B.S.", "Uni", 3.64));
            //log.info("Preloading " + repository.save(a));
            
        };
    }

}

编辑：这是教育课：

public class Education {
    private String degree;
    private String institute;
    private double gpa;
    Education(String degree, String institute, double gpa) {
        this.setDegree(degree);
        this.setInstitute(institute);
        this.setGpa(gpa);
    }
    public String getDegree() {
        return degree;
    }
    public void setDegree(String degree) {
        this.degree = degree;
    }
    public String getInstitute() {
        return institute;
    }
    public void setInstitute(String institute) {
        this.institute = institute;
    }
    public double getGpa() {
        return gpa;
    }
    public void setGpa(double gpa) {
        this.gpa = gpa;
    }
    @Override
    public String toString() {
        String s = "{";
        s += s += String.format("\"degree\": \"%s\"", this.degree);
        s += String.format("\"institute\": \"%s\"", this.institute);
        s += String.format("\"gpa\": %.2f", this.gpa);
        s += "}";
        return s;
    }
}

Answer 1

https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/list.html

问题是，只要您的列表是动态的，就不能序列化，而是需要序列化才能能够传输到数据库。所以您必须确保您的列表是可序列化的。这是通过“List.of和List.CopyOf静态工厂方法提供了创建不可修改列表的便捷方式”来实现的。这意味着，在将对象发送到数据库之前，必须确保列表对象是不可修改的/不是动态的。