Java Hibernate：一对多双向映射存储

事实上，我对hibernate还不熟悉，正在研究一对多双向映射。关系是这样的

一个用户拥有多个博客

一个用户拥有多个论坛

根据我的理解，如果我们在博客模型中使用@ManyToOne注释和@JoinColumn，那么就没有必要在博客中明确添加外键（用户id）列。但问题是，当我试图持久化数据时，用户id列采用空值。如果我在blog模型中显式地编写userid属性及其getter和setter，那么一切都可以正常工作

Users.java

@Entity
@Table

public class Users {

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator= "generator")
@SequenceGenerator(name = "generator" , sequenceName="users_seq" , allocationSize=1)
private int user_id;

private String name,password,email,role,status,isOnline;

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Blog> blog = new ArrayList<Blog>();

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Forum> forum = new ArrayList<Forum>();

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Friend> friend =  new ArrayList<Friend>();

public List<Forum> getForum() {
    return forum;
}

public List<Friend> getFriend() {
    return friend;
}

public void setFriend(List<Friend> friend) {
    this.friend = friend;
}

public void setForum(List<Forum> forum) {
    this.forum = forum;
}

public List<Blog> getBlog() {
    return blog;
}

public void setBlog(List<Blog> blog) {
    this.blog = blog;
}

public int getUser_id() {
    return user_id;
}

public void setUser_id(int user_id) {
    this.user_id = user_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 getRole() {
    return role;
}

public void setRole(String role) {
    this.role = role;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public String getIsOnline() {
    return isOnline;
}

public void setIsOnline(String isOnline) {
    this.isOnline = isOnline;
}

@Entity
@Table
public class Blog {

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator= "generator")
@SequenceGenerator(name = "generator" , sequenceName="blog_seq" , allocationSize=1)
private int blog_id;

private int likes,user_id; // I need to explicitly write the user_id column here

public int getUser_id() {
    return user_id;
}

public void setUser_id(int user_id) {
    this.user_id = user_id;
}

private String blog_name,blog_content,status;

@Temporal(TemporalType.DATE)
private Date create_date;

@ManyToOne
@JoinColumn(name="user_id",insertable=false, updatable=false) // This step will actually add the user_id column in the Blog model but it's not happening
@JsonBackReference
private Users user;

public Users getUser() {
    return user;
}

public void setUser(Users user) {
    this.user = user;
}

public int getBlog_id() {
    return blog_id;
}

public void setBlog_id(int blog_id) {
    this.blog_id = blog_id;
}

public int getLikes() {
    return likes;
}

public void setLikes(int likes) {
    this.likes = likes;
}

public String getBlog_name() {
    return blog_name;
}

public void setBlog_name(String blog_name) {
    this.blog_name = blog_name;
}

public String getBlog_content() {
    return blog_content;
}

public void setBlog_content(String blog_content) {
    this.blog_content = blog_content;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public Date getCreate_date() {
    return create_date;
}

public void setCreate_date(Date create_date) {
    this.create_date = create_date;
}

@EnableTransactionManagement
@Repository("blogDAO")
public class BlogDAOImpl implements BlogDAO {

@Autowired
SessionFactory sessionFactory;

public BlogDAOImpl(SessionFactory sessionFactory) {
    super();
    this.sessionFactory = sessionFactory;
}

public BlogDAOImpl() {
    super();
    // TODO Auto-generated constructor stub
}

@Transactional
public boolean addOrUpdateBlog(Blog blog) {
    try{
        sessionFactory.getCurrentSession().saveOrUpdate(blog);
        return true;
    }
    catch(Exception e)
    {
        System.out.println("Exception in addOrUpdateBlog of BlogDAOImpl");
        e.printStackTrace();
        return false;
    }
}

@Transactional
public boolean deleteBlog(Blog blog) {
    try
    {
        sessionFactory.getCurrentSession().delete(blog);
        return true;
    }
    catch(Exception e)
    {
        System.out.println("Exception in deleteBlog of BlogDAOImpl");
        e.printStackTrace();
        return false;
    }
}

@Transactional
public List<Blog> getListOfBlog() {
    try
    {
        String hql = "from Blog";
        Session session = sessionFactory.openSession();
        Query query = session.createQuery(hql);
        List<Blog> bloglist = query.list();
        session.close();
        return bloglist;
    }
    catch(Exception e)
    {
        System.out.println("Exception in getListOfBlog of BlogDAOImpl");
        e.printStackTrace();
        return null;
    }
}

@Transactional
public Blog getParticularBlog(int blogid) {
    try
    {
        return (Blog) sessionFactory.getCurrentSession().get(Blog.class, blogid);
    }
    catch(Exception e)
    {
        System.out.println("Exception in getParticularBlog of BlogDAOImpl");
        e.printStackTrace();
        return null;
    }
    }

}

}

BlogDAOImpl.java

@Entity
@Table

public class Users {

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator= "generator")
@SequenceGenerator(name = "generator" , sequenceName="users_seq" , allocationSize=1)
private int user_id;

private String name,password,email,role,status,isOnline;

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Blog> blog = new ArrayList<Blog>();

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Forum> forum = new ArrayList<Forum>();

@OneToMany(mappedBy="user",cascade=CascadeType.ALL,fetch=FetchType.EAGER)
@JsonManagedReference
private List<Friend> friend =  new ArrayList<Friend>();

public List<Forum> getForum() {
    return forum;
}

public List<Friend> getFriend() {
    return friend;
}

public void setFriend(List<Friend> friend) {
    this.friend = friend;
}

public void setForum(List<Forum> forum) {
    this.forum = forum;
}

public List<Blog> getBlog() {
    return blog;
}

public void setBlog(List<Blog> blog) {
    this.blog = blog;
}

public int getUser_id() {
    return user_id;
}

public void setUser_id(int user_id) {
    this.user_id = user_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 getRole() {
    return role;
}

public void setRole(String role) {
    this.role = role;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public String getIsOnline() {
    return isOnline;
}

public void setIsOnline(String isOnline) {
    this.isOnline = isOnline;
}

@Entity
@Table
public class Blog {

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator= "generator")
@SequenceGenerator(name = "generator" , sequenceName="blog_seq" , allocationSize=1)
private int blog_id;

private int likes,user_id; // I need to explicitly write the user_id column here

public int getUser_id() {
    return user_id;
}

public void setUser_id(int user_id) {
    this.user_id = user_id;
}

private String blog_name,blog_content,status;

@Temporal(TemporalType.DATE)
private Date create_date;

@ManyToOne
@JoinColumn(name="user_id",insertable=false, updatable=false) // This step will actually add the user_id column in the Blog model but it's not happening
@JsonBackReference
private Users user;

public Users getUser() {
    return user;
}

public void setUser(Users user) {
    this.user = user;
}

public int getBlog_id() {
    return blog_id;
}

public void setBlog_id(int blog_id) {
    this.blog_id = blog_id;
}

public int getLikes() {
    return likes;
}

public void setLikes(int likes) {
    this.likes = likes;
}

public String getBlog_name() {
    return blog_name;
}

public void setBlog_name(String blog_name) {
    this.blog_name = blog_name;
}

public String getBlog_content() {
    return blog_content;
}

public void setBlog_content(String blog_content) {
    this.blog_content = blog_content;
}

public String getStatus() {
    return status;
}

public void setStatus(String status) {
    this.status = status;
}

public Date getCreate_date() {
    return create_date;
}

public void setCreate_date(Date create_date) {
    this.create_date = create_date;
}

@EnableTransactionManagement
@Repository("blogDAO")
public class BlogDAOImpl implements BlogDAO {

@Autowired
SessionFactory sessionFactory;

public BlogDAOImpl(SessionFactory sessionFactory) {
    super();
    this.sessionFactory = sessionFactory;
}

public BlogDAOImpl() {
    super();
    // TODO Auto-generated constructor stub
}

@Transactional
public boolean addOrUpdateBlog(Blog blog) {
    try{
        sessionFactory.getCurrentSession().saveOrUpdate(blog);
        return true;
    }
    catch(Exception e)
    {
        System.out.println("Exception in addOrUpdateBlog of BlogDAOImpl");
        e.printStackTrace();
        return false;
    }
}

@Transactional
public boolean deleteBlog(Blog blog) {
    try
    {
        sessionFactory.getCurrentSession().delete(blog);
        return true;
    }
    catch(Exception e)
    {
        System.out.println("Exception in deleteBlog of BlogDAOImpl");
        e.printStackTrace();
        return false;
    }
}

@Transactional
public List<Blog> getListOfBlog() {
    try
    {
        String hql = "from Blog";
        Session session = sessionFactory.openSession();
        Query query = session.createQuery(hql);
        List<Blog> bloglist = query.list();
        session.close();
        return bloglist;
    }
    catch(Exception e)
    {
        System.out.println("Exception in getListOfBlog of BlogDAOImpl");
        e.printStackTrace();
        return null;
    }
}

@Transactional
public Blog getParticularBlog(int blogid) {
    try
    {
        return (Blog) sessionFactory.getCurrentSession().get(Blog.class, blogid);
    }
    catch(Exception e)
    {
        System.out.println("Exception in getParticularBlog of BlogDAOImpl");
        e.printStackTrace();
        return null;
    }
    }

}

@EnableTransactionManagement
@存储库（“blogDAO”）
公共类BlogDAOImpl实现BlogDAO{
@自动连线
会话工厂会话工厂；
公共BlogDAOImpl（SessionFactory SessionFactory）{
超级（）；
this.sessionFactory=sessionFactory；
}
公共BlogDAOImpl（）{
超级（）；
//TODO自动生成的构造函数存根
}
@交易的
公共布尔addOrUpdateBlog（博客）{
试一试{
sessionFactory.getCurrentSession（）.saveOrUpdate（博客）；
返回true；
}
捕获（例外e）
{
System.out.println（“BlogDAOImpl的addOrUpdateBlog中的异常”）；
e、 printStackTrace（）；
返回false；
}
}
@交易的
公共博客（Blog Blog）{
尝试
{
sessionFactory.getCurrentSession（）.delete（博客）；
返回true；
}
捕获（例外e）
{
System.out.println（“BlogDAOImpl的deleteBlog中的异常”）；
e、 printStackTrace（）；
返回false；
}
}
@交易的
公共列表getListOfBlog（）{
尝试
{
字符串hql=“from Blog”；
Session Session=sessionFactory.openSession（）；
Query=session.createQuery（hql）；
List bloglist=query.List（）；
session.close（）；
返回博客列表；
}
捕获（例外e）
{
System.out.println（“BlogDAOImpl的getListOfBlog中的异常”）；
e、 printStackTrace（）；
返回null；
}
}
@交易的
公共博客GetSpecificularBlog（intBlogId）{
尝试
{
return（Blog）sessionFactory.getCurrentSession（）.get（Blog.class，blogid）；
}
捕获（例外e）
{
System.out.println（“BlogDAOImpl的getSpecificularBlog中的异常”）；
e、 printStackTrace（）；
返回null；
}
}
}

博客REST控制器

package com.coding.blogandforum.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.coding.blogandforum.DAO.BlogDAO;
import com.coding.blogandforum.DAO.UserDAO;
import com.coding.blogandforum.model.Blog;
import com.coding.blogandforum.model.Users;

@RestController
public class BlogController {

    @Autowired
    BlogDAO blogDAO;

    @Autowired
    Blog blog;

    @Autowired
    Users user;

    @Autowired
    UserDAO userDAO;

    // To get the list of all the blog objects
    @RequestMapping(value="/getListOfBlog", method=RequestMethod.GET)
    public ResponseEntity<List<Blog>> getListOfBlog()
    {
        List<Blog> bloglist = blogDAO.getListOfBlog();
        return new ResponseEntity<List<Blog>>(bloglist,HttpStatus.OK);
    }

    /*
     * To get a particular Blog details using blog id
     * In postman, blog details are only displayed.
    */
    @RequestMapping(value="/getParticularBlog/{blogid}", method=RequestMethod.GET)
    public ResponseEntity<Blog> getParticularBlog(@PathVariable("blogid") int blogid)
    {
        Blog particularblog = blogDAO.getParticularBlog(blogid);
        return new ResponseEntity<Blog>(particularblog,HttpStatus.OK);
    }

    /* 
     * To get a particular user details with blogid 
     * In postman the user will display the blog and forum details along with it
     */
    @RequestMapping(value="/getUserDetailsWithBlogid/{blogid}", method=RequestMethod.GET)
    public ResponseEntity<Users> getUserDetailsWithBlogid(@PathVariable("blogid") int blogid)
    {
        Blog blogwithuser = blogDAO.getParticularBlog(blogid);
        return new ResponseEntity<Users>(blogwithuser.getUser(),HttpStatus.OK);
    }

    // To add a particular blog details in the DB
    @RequestMapping(value="/addBlog", method=RequestMethod.POST)
    public ResponseEntity<String> addBlog(@RequestBody Blog blog)
    {
        System.out.println(blog.getUser());
        blog.setStatus("PENDING");
        blogDAO.addOrUpdateBlog(blog);
        return new ResponseEntity<String>("Blog added successfully",HttpStatus.OK);
    }

    // To delete a particular blog from the DB
    @RequestMapping(value="/deleteBlog/{blogid}", method=RequestMethod.DELETE)
    public ResponseEntity<String> deleteBlog(@PathVariable("blogid") int blogid)
    {
        blogDAO.deleteBlog(blogDAO.getParticularBlog(blogid));
        return new ResponseEntity<String>("Blog deleted successfully",HttpStatus.OK);
    }

    /*
     * To update a particular blog
     * Date will not be displayed as YYYY-MM-DD in postman since the updateblog date property is not temporal
     */
    @RequestMapping(value="/updateBlog/{blogid}", method=RequestMethod.PUT)
    public ResponseEntity<Blog> updateBlog(@PathVariable("blogid") int blogid, @RequestBody Blog blog)
    {
        Blog updateblog = blogDAO.getParticularBlog(blogid);
        //updateblog.setBlog_content(blog.getBlog_content());
        updateblog.setCreate_date(blog.getCreate_date());
        blogDAO.addOrUpdateBlog(updateblog);
        return new ResponseEntity<Blog>(updateblog,HttpStatus.OK);
    }
}

package com.coding.blogandforum.controller；
导入java.util.List；
导入org.springframework.beans.factory.annotation.Autowired；
导入org.springframework.http.HttpStatus；
导入org.springframework.http.ResponseEntity；
导入org.springframework.web.bind.annotation.PathVariable；
导入org.springframework.web.bind.annotation.RequestBody；
导入org.springframework.web.bind.annotation.RequestMapping；
导入org.springframework.web.bind.annotation.RequestMethod；
导入org.springframework.web.bind.annotation.RestController；
导入com.coding.blogandforum.DAO.BlogDAO；
导入com.coding.blogandforum.DAO.UserDAO；
导入com.coding.blogandforum.model.Blog；
导入com.coding.blogandforum.model.Users；
@RestController
公共类BlogController{
@自动连线
BlogDAO BlogDAO；
@自动连线
博客；
@自动连线
用户；
@自动连线
UserDAO UserDAO；
//获取所有博客对象的列表
@RequestMapping（value=“/getListOfBlog”，method=RequestMethod.GET）
公共响应getListOfBlog（）
{
List bloglist=blogDAO.getListOfBlog（）；
返回新的ResponseEntity（bloglist，HttpStatus.OK）；
}
/*
*使用博客id获取特定博客详细信息
*在postman中，只显示博客详细信息。
*/
@RequestMapping（value=“/GetSpecificularBlog/{blogid}”，method=RequestMethod.GET）
公共响应属性GetSpecificularBlog（@PathVariable（“blogid”）intBlogId）
{
Blog specificularblog=blogDAO.getspecificularblog（blogid）；
返回新的ResponseEntity（特别是rblog、HttpStatus.OK）；
}
/* 
*使用blogid获取特定用户的详细信息
*在postman中，用户将显示博客和论坛的详细信息
*/
@RequestMapping（value=“/getUserDetailsWithBlogid/{blogid}”，method=RequestMethod.GET）
公共响应属性getUserDetailsWithBlogid（@PathVariable（“blogid”）intBlogId）
{
blogBlogWithUser=blogDAO.getSpecificularBlog（blogid）；
返回新的ResponseEntity（blogwithuser.getUser（），HttpStatus.OK）；
}
//在数据库中添加特定博客详细信息
@RequestMapping（value=“/addBlog”，method=RequestMethod.POST）
公共响应性addBlog（@RequestBody Blog）
{
System.out.println（blog.getUser（））；
blog.setStatus（“待定”）；
addOrUpdateBlog（blog）；
返回新的响应状态（“博客添加成功”，HttpStatus.OK）；
}
//从数据库中删除特定博客的步骤
@RequestMapping（value=“/deleteBlog/{blogid}”，method=RequestMethod.DELETE）
公共响应属性deleteBlog（@PathVariable（“blogid”）int blogid）
{
deleteBlog（blogDAO.getSpecificularBlog（blogid））；
返回新的响应状态（“博客删除成功”，HttpStatus.OK）；
}
/*
*更新特定博客的步骤
*由于updateblog Date属性不是临时属性，因此日期在postman中不会显示为YYYY-MM-DD
*/
@RequestMapping（value=“/updateBlog/{blogid}”，method=RequestMethod.PUT）
公共响应性更新日志（@PathVariable（“blogid”）int blogid，@RequestBody Blog）
{
Blog updateblog=blogDAO.getspecificularblog（blogid）；
//updateblog.setBlog_content（blog.getBlog_content（））；
updateblog.setCreate_date（blog.getCreate_date（））；
blogDAO.addorupdate