当尝试从链接到另一个实体的用户获取详细信息时，它会出现 StackOverflow 错误

Question

我正在努力学习休眠，因为我正在尝试制作一个应用程序，用户可以在其中添加一些产品，当我们获取用户并调用产品列表时，它应该获取该特定添加的产品用户为此我已经定义了用户和产品之间的@OneToMany映射但是当我试图获取有一些产品的用户时它给我 Whosebug 错误但是当我打电话给没有产品的用户时它工作正常.这是我的代码，请看一下，请让我知道我在这里做错了什么。

UserModel.java

package com.solitera.model;

import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="user")
public class UserModel {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private Integer id;
    @Column(name="user_name")
    private String name;
    @Column(name="user_password")
    private String password;
    @Column(name="user_email")
    private String email;
    @Column(name="user_address")
    private String address;
    @Column(name="user_phone")
    private String phoneNumber;
    @Column(name="user_role")
    private Integer role;

    @OneToMany(mappedBy = "addedBy" ,cascade = CascadeType.ALL,fetch = FetchType.LAZY)
//  @JoinColumn(name="added_by")
    private List<ProductModel> products;
    
        
    public UserModel() {
    }


    public UserModel(String name, String password, String email, String address, String phoneNumber, Integer role) {
        this.name = name;
        this.password = password;
        this.email = email;
        this.address = address;
        this.phoneNumber = phoneNumber;
        this.role = role;
    }


    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }

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

    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }

    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    
    public String getPhoneNumber() {
        return phoneNumber;
    }
    public void setPhoneNumber(String phoneNumber) {
        this.phoneNumber = phoneNumber;
    }

    public Integer getRole() {
        return role;
    }
    public void setRole(Integer role) {
        this.role = role;
    }


    public List<ProductModel> getProducts() {
        return products;
    }
    public void setProducts(List<ProductModel> products) {
        this.products = products;
    }


    @Override
    public String toString() {
        return "{\"id\":\"" + id + "\", \"name\":\"" + name + "\", \"password\":\"" + password + "\", \"email\":\""
                + email + "\", \"address\":\"" + address + "\", \"phoneNumber\":\"" + phoneNumber + "\", \"role\":\""
                + role + "\", \"products\":\"" + products + "\"}";
    }   
    
}

ProductModel.java

package com.solitera.model;

import java.sql.Date;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="products")
public class ProductModel {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="id")
    private Integer id;
    @Column(name="name")
    private String name; 

    @ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name="added_by")
    private UserModel addedBy;

    @Column(name="price")
    private Integer price;
    
    @OneToMany(mappedBy = "productid" , cascade = CascadeType.ALL)
    private List<PictureModel> pictures;
    
    public ProductModel() {
    }


    public ProductModel(String name, UserModel addedBy, Integer price) {
        this.name = name;
        this.addedBy = addedBy;
        this.price = price;
    }


    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }

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

    public UserModel getAddedBy() {
        return addedBy;
    }
    public void setAddedBy(UserModel addedBy) {
        this.addedBy = addedBy;
    }

    public Integer getPrice() {
        return price;
    }
    public void setPrice(Integer price) {
        this.price = price;
    }

    public List<PictureModel> getPictures() {
        return pictures;
    }
    public void setPictures(List<PictureModel> pictures) {
        this.pictures = pictures;
    }


    @Override
    public String toString() {
        return "{\"id\":\"" + id + "\", \"name\":\"" + name + "\", \"addedBy\":\"" + addedBy + "\", \"price\":\""
                + price + "\", \"pictures\":\"" + pictures + "\"}";
    }



    
}

UserServiceImpl.java

 public UserModel getuser(UserModel userModel,EntityManager entityManager) {
     Boolean isIntMgr = false;
     
     if(entityManager == null) {
         entityManager = MyEntityManagerFactory.getEntityManagerFactory().createEntityManager();
         entityManager.getTransaction().begin();
         isIntMgr =true;
     }
     Integer id= 8;
     
     userModel = entityManager.find(UserModel.class,id);
     
     logger.info("The user Model for USer id 8 is : "+ userModel );
     logger.info("This are the products : " + userModel.getProducts());
//   for(ProductModel products : userModel.getProducts()) {
//       logger.info("This are the products : " + products);
//   }  
     if(isIntMgr) {
         entityManager.getTransaction().commit();
     }
     return userModel;
 }

控制台

04:09:2020 00:02:38 [LogHelper] HHH000204: Processing PersistenceUnitInfo [
    name: my_test_eCommerce
    ...]
04:09:2020 00:02:38 [Version] HHH000412: Hibernate Core {5.3.2.Final}
04:09:2020 00:02:38 [Environment] HHH000206: hibernate.properties not found
04:09:2020 00:02:39 [Version] HCANN000001: Hibernate Commons Annotations {5.0.4.Final}
[main] INFO com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Starting...
[main] INFO com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Start completed.
04:09:2020 00:02:39 [Dialect] HHH000400: Using dialect: org.hibernate.dialect.MySQL8Dialect
Hibernate: 
    select
        usermodel0_.id as id1_2_0_,
        usermodel0_.user_address as user_add2_2_0_,
        usermodel0_.user_email as user_ema3_2_0_,
        usermodel0_.user_name as user_nam4_2_0_,
        usermodel0_.user_password as user_pas5_2_0_,
        usermodel0_.user_phone as user_pho6_2_0_,
        usermodel0_.user_role as user_rol7_2_0_ 
    from
        user usermodel0_ 
    where
        usermodel0_.id=?
Hibernate: 
    select
        products0_.added_by as added_by4_1_0_,
        products0_.id as id1_1_0_,
        products0_.id as id1_1_1_,
        products0_.added_by as added_by4_1_1_,
        products0_.name as name2_1_1_,
        products0_.price as price3_1_1_ 
    from
        products products0_ 
    where
        products0_.added_by=?
04:09:2020 00:02:40 [UserServiceImpl] --------------------Finally in Main ---------------------
Exception in thread "main" java.lang.WhosebugError
    at java.base/java.lang.Integer.toString(Integer.java:441)
    at java.base/java.lang.Integer.toString(Integer.java:1165)
    at java.base/java.lang.String.valueOf(String.java:2801)
    at java.base/java.lang.StringBuilder.append(StringBuilder.java:135)
    at com.solitera.model.ProductModel.toString(ProductModel.java:88)
    at java.base/java.lang.String.valueOf(String.java:2801)
    at java.base/java.lang.StringBuilder.append(StringBuilder.java:135)
    at java.base/java.util.AbstractCollection.toString(AbstractCollection.java:473)

Answer 1

您应该从 UserModel.toString()

中删除 products

    @Override
    public String toString() {
        return "{\"id\":\"" + id + "\", \"name\":\"" + name + "\", \"password\":\"" + password + "\", \"email\":\""
                + email + "\", \"address\":\"" + address + "\", \"phoneNumber\":\"" + phoneNumber + "\", \"role\":\""
                + role + "\"}";
    }

由于用户的toString调用产品的toString等，出现Whosebug错误。

当尝试从链接到另一个实体的用户获取详细信息时，它会出现 StackOverflow 错误

When trying to fetch details from user which linked to another entity it gives StackOverflow Error

mysql

hibernate

jpa

one-to-many

many-to-one