Spring + JPA（Hibernate）ORM

我试图做一个迷你论坛，我被​​卡住了。 它应该是什么，首先，你创建一个帖子，写一个主题的消息，它重定向到所有帖子并添加你创建的新发布，​​用户点击一个帖子，并在下一页显示所有消息填充我也做了一个评论系统，我每个帖子都必须有评论，所以问题出现在我的代码下面，当我试图让评论工作时，它的工作原理是这样的：无论你发布什么帖子选择它显示所有确实存在的评论，所以我改变了并且失败了。 可能有人解释我，如何使Hibernate正确。

PostController是：注意方法seeMessage，它通过id找到帖子并显示消息。

    package com.pandora.controllers;



    import com.pandora.domain.Post;
    import com.pandora.services.CommentService;
    import com.pandora.services.PostService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.ui.Model;
    import org.springframework.web.bind.annotation.ModelAttribute;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;



    @Controller
    @RequestMapping("/posts")
    public class PostController {

        @Autowired
        private PostService postService;

        @Autowired
        private CommentService commentService;

        @RequestMapping
        public String findAll(Model model) {
            model.addAttribute("posts", postService.findAll());
            return "post/post";
        }

        @RequestMapping(value = "/click", method = RequestMethod.GET)
        public String click() {
            return "post/new";
        }

        @RequestMapping(value = "/add", method = RequestMethod.POST)
        public String addPost(@ModelAttribute Post post) {
            postService.addPost(post);
            return "redirect:/posts";
        }

        @RequestMapping(value = "/{title}/find", method = RequestMethod.GET)
        public String findByName(@PathVariable String title) {
            postService.findByTitle(title);
            return "redirect:/posts";
        }

        @RequestMapping(value = "/{id}/see", method = RequestMethod.GET)
        public String seeMessage(@PathVariable long id, Model model) {
            Post post = postService.findById(id);
            System.out.println("the id is " + id);
            System.out.println("the value of comments are " +post.getComments().size());

            model.addAttribute("post", post);
    //        model.addAttribute("postMessage", post.getComments());

            return "post/postmessage";


        }


        @RequestMapping(value = "/{id}/delete")
        public String delete(@PathVariable long id) {
            postService.delete(id);
            return "redirect:/posts";
        }

        @RequestMapping(value = "/login", method = RequestMethod.GET)
        public String login(){
            return "login";
        }

    }

CommentController是：在这里注意方法addComment，首先我从什么id发布它去了，并在此之后，我不得不添加评论创建职位。

    package com.pandora.controllers;

    import com.pandora.domain.Comment;

    import com.pandora.domain.Post;
    import com.pandora.services.CommentService;
    import com.pandora.services.PostService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.ModelAttribute;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;

    import java.util.ArrayList;
    import java.util.List;

    @Controller
    @RequestMapping("/comments")
    public class CommentController {

        @Autowired
        private CommentService commentService;

        @Autowired
        private PostService postService;

        @RequestMapping(value = "/post/{postId}/comment", method = RequestMethod.POST)
        public String addComment(@PathVariable long postId, @ModelAttribute Comment comment){

            Post post = postService.findById(postId);

            System.out.println(post.getId());
            System.out.println(comment.getMessage());

            List comments = new ArrayList();

            comments.add(commentService.addComment(comment));

            post.setComments(comments);

            return "redirect:/posts";
        }

        @RequestMapping(value = "/{id}/delete", method = RequestMethod.GET)
        public String delete(@PathVariable long id){
            commentService.delete(id);
            return "redirect:/posts";
        }

    }

邮政实体是：

    package com.pandora.domain;

    import lombok.Getter;
    import lombok.NoArgsConstructor;
    import lombok.Setter;

    import javax.persistence.*;
    import java.util.List;

    @Entity
    @Setter
    @Getter
    @NoArgsConstructor
    public class Post {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private long id;

        @OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "post")
        private List comments;

        @Column(length = 10000)
        private String message;

        private String title;
    }

PostService是：

    package com.pandora.services;

    import com.pandora.domain.Post;
    import com.pandora.domain.repositories.PostRepository;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;

    import java.util.List;

    @Service
    public class PostService {

        @Autowired
        private PostRepository postRepository;

        public Post addPost(Post post){
            return postRepository.saveAndFlush(post);
        }

        public List findAll(){
            return postRepository.findAll();
        }

        public Post findByTitle(String title){
            return postRepository.findByTitle(title);
        }

        public Post findById(long id){
            return postRepository.findOne(id);
        }

        public void delete(long id){
            postRepository.delete(id);
        }



    }

评论实体是：

    package com.pandora.domain;

    import lombok.Getter;
    import lombok.NoArgsConstructor;
    import lombok.Setter;

    import javax.persistence.*;

    @Entity
    @Setter
    @Getter
    @NoArgsConstructor
    public class Comment {

        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private long id;

        @ManyToOne(fetch = FetchType.EAGER)
        private Post post;

        private String message;


    }

和CommentService是：

package com.pandora.services;

    import com.pandora.domain.Comment;
    import com.pandora.domain.repositories.CommentRepository;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;

    import java.util.List;

    @Service
    public class CommentService {

        @Autowired
        private CommentRepository commentRepository;

        public Comment addComment(Comment comment){
            return commentRepository.saveAndFlush(comment);
        }

        public List findAll(){
            return commentRepository.findAll();
        }

        public void delete(long id){
            commentRepository.delete(id);
        }

        public Comment findOne(long id){
            return commentRepository.findOne(id);
        }


    }

并显示其选择的帖子是HTML：这里要注意：每个div容器。 我从PostController注释中删除的列表中检索。 但它不起作用，因为当我这样做时，它总是空的。 我不知道为什么它是空的。

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"
      layout:decorator="layout">

<div layout:fragment="content">

    <h2 align="center">
        <h2 align="left">
            <div th:text="${post.title}"></div>
        </h2>
    </h2>

    <h4 align="center">
        <div th:text="${post.message}"></div>
    </h4>
    <hr/>
    <h4>Comments:</h4>
    <br/>

   
    
    <h4>
        <div th:each="comments : ${post}">
           
            <label for="username"><div th:inline="text">[[${#httpServletRequest.remoteUser}]]: </div> </label>
            <div  th:each="comment : ${comments.comments}">
                <div  id="username" th:text="${comment}"></div>
            </div>
        </div>
    </h4>


    <br/>
    <form method="post" name="comment_form" id="comment_form" th:action="@{'/comments/post/{id}/comment'(id=${post.id}) }" role="form">
        <div class="form-group">
            <label for="message">Comment</label>
            <textarea rows="5" class="form-control" id="message" name="message"/>
        </div>
        <button type="submit" id="submit" class="btn btn-primary">Submit</button>
    </form>


</div>

</html>

链接地址: http://www.djcxy.com/p/8611.html

上一篇: Spring + JPA( Hibernate) ORM

下一篇: Stop cell editing in JTable with JRadioButton as cell renderers