SpringBoot+Spring Data JPA 实现留言评论，评论回复

言曌 2018年04月23日22:06:17 22 21464 views

博主分享免费Java教学视频，B站账号：Java刘哥，长期提供技术问题解决、项目定制：本站商品点此

先看效果图

样式是模仿哔哩哔哩的，支持二级评论。

动态效果图如下，点击图片放大

一、数据库设计

Comment 表

id：主键，自定生成

content：评论内容，限制500个字符

create_time：创建时间，自动生成

user_id：评论的用户的id

post_id：评论所在文章的id

pid：评论的父id，注意A评论下的所有子评论，我这里都设计为他的儿子，而不是儿子，孙子，曾孙。即，回复的回复，回复的回复的回复的pid都是某个一级评论。这样设计，主要是为了二级显示和避免太多递归（多级显示太麻烦了，/(ㄒoㄒ)/~~）

reply_user_id：被回复人的id，用于@对方时候显示。对一级评论进行评论不需要@他，所以reply_user_id 为空，对回复回复需要@对方，否则不知道回复谁。

再补充一下，解释一下上面的。

如图，柯南的评论属于一级评论，有楼层号显示。小兰回复柯南，灰原哀回复小兰，琴酒回复灰原哀。小兰、灰原哀、琴酒的 pid 都是柯南的 id，而柯南的 pid 为 0。

二、JPA 实体

Post.java 文章实体

package com.liuyanzhao.forum.entity;
import lombok.Data;
import org.hibernate.annotations.Where;
import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.Size;
import java.io.Serializable;
import java.util.List;
/**
* @author 言曌
* @date 2018/3/19 下午9:54
*/
@Entity
@Data
public class Post implements Serializable {
private static final long serialVersionUID = -5086173193716866676L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY) // 自增长策略
@Column(name = "id", nullable = false)
private Long id;
@NotEmpty(message = "标题不能为空")
@Size(max = 200, message = "标题不能超过200个字符")
@Column(nullable = false, length = 200)
private String title;
@Lob // 大对象，映射 MySQL 的 Long Text 类型
@Basic(fetch = FetchType.LAZY) // 懒加载
@NotEmpty(message = "内容不能为空")
@Size(max = 100000, message = "内容不能超过100000个字符")
@Column(nullable = false)
private String content;//文章全文内容
@Column(name = "comment_size")
private Integer commentSize = 0; // 评论数
//当文章删除后，与之关联的评论也会被删除
@OneToMany(mappedBy = "post", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@OrderBy("id DESC")
@Where(clause = "pid=0")
private List<Comment> commentList;
public Post() {
}
}

这里去掉了不必要的代码

Comment.java 评论实体

package com.liuyanzhao.forum.entity;
import lombok.Data;
import javax.persistence.*;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.Size;
import java.io.Serializable;
import java.sql.Timestamp;
import java.util.List;
/**
* 评论实体
* @author 言曌
* @date 2018/3/19 下午9:54
*/
@Entity
@Data
public class Comment implements Serializable {
private static final long serialVersionUID = -4502134548520740266L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY) // 自增长策略
private Long id;
@Column(name = "pid", nullable = false)
private Long pid = 0L;//父评论，如果不设置，默认为0
@NotEmpty(message = "评论内容不能为空")
@Size(max = 500, message = "评论内容不能多于500个字符")
@Column(nullable = false)
private String content;
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "user_id")
private User user;
@Column(nullable = false)
@org.hibernate.annotations.CreationTimestamp // 由数据库自动创建时间
private Timestamp createTime;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "post_id")
private Post post;//所属文章
@OneToMany(fetch = FetchType.LAZY)//不设置级联，使用懒加载
@JoinColumn(name = "pid", referencedColumnName = "id")
@OrderBy("id ASC")
private List<Comment> commentList;
@JoinColumn(name = "reply_user_id")
@OneToOne(fetch = FetchType.LAZY)//不设置级联，使用懒加载
private User replyUser;
public Comment() {
}
public Comment(User user,Post post, String content) {
this.post = post;
this.content = content;
this.user = user;
}
public Comment(User user, Post post, Long pid, String content) {
this.user = user;
this.post = post;
this.pid = pid;
this.content = content;
}
@Override
public String toString() {
return "Comment{" +
"id=" + id +
", pid=" + pid +
", content='" + content + '\'' +
", createTime=" + createTime +
'}';
}
}

三、DAO 层

本项目采用的是 Spring Data JPA 作为 ORM 框架

package com.liuyanzhao.forum.repository;
import com.liuyanzhao.forum.entity.Comment;
import com.liuyanzhao.forum.entity.Post;
import org.springframework.data.jpa.repository.JpaRepository;
/**
* @author 言曌
* @date 2018/4/1 上午9:32
*/
public interface CommentRepository extends JpaRepository<Comment, Long> {
/**
* 统计某篇文章有多少条评论
* @param post
* @return
*/
Integer countByPost(Post post);
}

因为我们在 Post 实体中关联查询评论列表，只查询一级评论，其中二级评论由 Comment 实体中的 CommentList 查询。

@Where(clause = "pid=0")
private List<Comment> commentList;

但是，前台需要显示评论数，也就是 Post 表中的字段 commentSize 需要及时更改，所以我们采用每次从数据库查询的方式来解决。

如果我们不使用 @Where(clause = "pid=0") ，获取评论数可以在 Post 实体中添加这个方法，用于设置评论数

/**
* 修改评论数
*
*/
public void updateCommentSize() {
this.commentSize = this.commentList.size();
}

但是，我们设置了 @Where(clause = "pid=0") ，所以获取的 size 是不准确。所以，这里解释了一下。

四、Service 层

CommentServiceImpl.java

package com.liuyanzhao.forum.service.impl;
import com.liuyanzhao.forum.entity.Comment;
import com.liuyanzhao.forum.entity.Post;
import com.liuyanzhao.forum.entity.User;
import com.liuyanzhao.forum.repository.CommentRepository;
import com.liuyanzhao.forum.repository.PostRepository;
import com.liuyanzhao.forum.service.CommentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
/**
* @author 言曌
* @date 2018/4/18 下午3:33
*/
@Service
public class CommentServiceImpl implements CommentService {
@Autowired
private CommentRepository commentRepository;
@Autowired
private PostRepository postRepository;
@Override
@Transactional
public void removeComment(Long id) {
commentRepository.deleteById(id);
}
@Override
public Integer countCommentSizeByPost(Post post) {
return commentRepository.countByPost(post);
}
@Override
public Comment getCommentById(Long id) {
return commentRepository.findById(id).get();
}
@Override
public void createComment(Long postId, String commentContent) {
Post post = postRepository.findById(postId).get();
User user = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
Comment comment = new Comment(user, post, commentContent);
commentRepository.save(comment);
}
@Override
public void replyComment(Long postId, Long commentId, Long replyId, String commentContent) {
Post post = postRepository.findById(postId).get();
User user = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
Comment comment = new Comment(user, post, commentId, commentContent);
//评论回复，需要加上@用户
if (replyId != null) {
Comment replyComment = commentRepository.findById(replyId).get();
comment.setReplyUser(replyComment.getUser());
}
//添加评论
commentRepository.save(comment);
}
}

五、Controller 层

PostController.java

文章详情页方法

/**
* 文章详情页
*
* @param username
* @param id
* @param model
* @return
*/
@GetMapping("/u/{username}/posts/{id}")
public String getPostById(@PathVariable("username") String username, @PathVariable("id") Long id, Model model) {
//1、每次读取，简单的可以认为阅读量增加1次
try {
postService.readingIncrease(id);
} catch (Exception e) {
//文章不存在
}
// 2、判断操作用户是否是博客的所有者
boolean isPostOwner = false;
if (SecurityContextHolder.getContext().getAuthentication() != null && SecurityContextHolder.getContext().getAuthentication().isAuthenticated()
&& !SecurityContextHolder.getContext().getAuthentication().getPrincipal().toString().equals("anonymousUser")) {
User principal = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
if (principal != null && username.equals(principal.getUsername())) {
isPostOwner = true;
}
}
Post post = postService.getPostById(id);
model.addAttribute("site_title", post.getTitle() + "-" + SITE_NAME);
model.addAttribute("isPostOwner", isPostOwner);
model.addAttribute("post", post);
return "home/post/detail";
}

CommentController.java

package com.liuyanzhao.forum.controller;
import com.liuyanzhao.forum.entity.Comment;
import com.liuyanzhao.forum.entity.Post;
import com.liuyanzhao.forum.entity.User;
import com.liuyanzhao.forum.repository.PostRepository;
import com.liuyanzhao.forum.service.CommentService;
import com.liuyanzhao.forum.service.PostService;
import com.liuyanzhao.forum.util.ConstraintViolationExceptionHandler;
import com.liuyanzhao.forum.vo.Response;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.security.access.prepost.PreAuthorize;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import javax.validation.ConstraintViolationException;
import java.util.List;
/**
* @author 言曌
* @date 2018/4/18 下午3:29
*/
@Controller
@RequestMapping("/comments")
public class CommentController {
@Autowired
private PostRepository postRepository;
@Autowired
private CommentService commentService;
/**
* 发表评论
*
* @param postId
* @param commentId
* @param commentContent
* @return
*/
@PostMapping
@PreAuthorize("hasAnyAuthority('ROLE_ADMIN','ROLE_USER')") // 指定角色权限才能操作方法
public ResponseEntity<Response> createComment(Long postId, Long replyId, Long commentId, String commentContent) {
try {
postRepository.findById(postId).get();
} catch (Exception e) {
return ResponseEntity.ok().body(new Response(false, "文章不存在!"));
}
try {
//1、评论
if (commentId == null) {
commentService.createComment(postId, commentContent);
} else {
//回复
commentService.replyComment(postId, commentId, replyId, commentContent);
}
//2、修改文章的评论数目
Post originalPost = postRepository.findById(postId).get();
originalPost.setCommentSize(commentService.countCommentSizeByPost(originalPost));
postRepository.save(originalPost);
} catch (ConstraintViolationException e) {
return ResponseEntity.ok().body(new Response(false, ConstraintViolationExceptionHandler.getMessage(e)));
} catch (Exception e) {
return ResponseEntity.ok().body(new Response(false, e.getMessage()));
}
return ResponseEntity.ok().body(new Response(true, "处理成功!", null));
}
/**
* 删除评论
*
* @return
*/
@DeleteMapping("/{id}")
@PreAuthorize("hasAnyAuthority('ROLE_ADMIN','ROLE_USER')") // 指定角色权限才能操作方法
public ResponseEntity<Response> delete(@PathVariable("id") Long id) {
boolean isOwner = false;
User user;
try {
user = commentService.getCommentById(id).getUser();
} catch (Exception e) {
return ResponseEntity.ok().body(new Response(false, "评论不存在！"));
}
// 判断操作用户是否是评论的所有者
if (SecurityContextHolder.getContext().getAuthentication() != null && SecurityContextHolder.getContext().getAuthentication().isAuthenticated()
&& !SecurityContextHolder.getContext().getAuthentication().getPrincipal().toString().equals("anonymousUser")) {
User principal = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
if (principal != null && user.getUsername().equals(principal.getUsername())) {
isOwner = true;
}
}
if (!isOwner) {
return ResponseEntity.ok().body(new Response(false, "没有操作权限！"));
}
try {
Comment originalComment = commentService.getCommentById(id);
//1、先删除子评论
List<Comment> commentList = originalComment.getCommentList();
if (commentList != null && commentList.size() != 0) {
for (int i = 0; i < commentList.size(); i++) {
Comment comment = commentList.get(i);
commentService.removeComment(comment.getId());
}
}
//2、删除该评论
commentService.removeComment(id);
//3、修改文章的评论数目
Post originalPost = originalComment.getPost();
originalPost.setCommentSize(commentService.countCommentSizeByPost(originalPost));
postRepository.save(originalPost);
} catch (ConstraintViolationException e) {
return ResponseEntity.ok().body(new Response(false, ConstraintViolationExceptionHandler.getMessage(e)));
} catch (Exception e) {
return ResponseEntity.ok().body(new Response(false, e.getMessage()));
}
return ResponseEntity.ok().body(new Response(true, "处理成功", null));
}
}