本篇内容介绍了“SpringBoot如何实现无限级评论回复功能”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
1 数据库表结构设计
表结构:
CREATE TABLE `comment` ( `id` bigint(18) NOT NULL AUTO_INCREMENT, `parent_id` bigint(18) NOT NULL DEFAULT '0', `content` text NOT NULL COMMENT '内容', `author` varchar(20) NOT NULL COMMENT '评论人', `create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '评论时间', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4;
数据添加:
INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (1, 0, '这是评论1', '吴名氏', '2023-02-20 17:11:16'); INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (2, 1, '我回复了第一条评论', '吴名氏', '2023-02-20 17:12:00'); INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (3, 2, '我回复了第一条评论的第一条回复', '吴名氏', '2023-02-20 17:12:13'); INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (4, 2, '我回复了第一条评论的第二条回复', '吴名氏', '2023-02-21 09:23:14'); INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (5, 0, '这是评论2', '吴名氏', '2023-02-21 09:41:02'); INSERT INTO `comment` (`id`, `parent_id`, `content`, `author`, `create_time`) VALUES (6, 3, '我回复了第一条评论的第一条回复的第一条回复', '吴名氏', '2023-02-21 09:56:27');
添加后的数据:
2 方案一
方案一先返回评论列表,再根据评论id返回回复列表,以此循环,具体代码下文进行展示
2.1 控制层CommentOneController.java
/**
* 方案一
* @author wuKeFan
* @date 2023-02-20 16:58:08
*/
@Slf4j
@RestController
@RequestMapping("/one/comment")
public class CommentOneController {
@Resource
private CommentService commentService;
@GetMapping("/")
public List<Comment> getList() {
return commentService.getList();
}
@GetMapping("/{id}")
public Comment getCommentById(@PathVariable Long id) {
return commentService.getById(id);
}
@GetMapping("/parent/{parentId}")
public List<Comment> getCommentByParentId(@PathVariable Long parentId) {
return commentService.getCommentByParentId(parentId);
}
@PostMapping("/")
public void addComment(@RequestBody Comment comment) {
commentService.addComment(comment);
}
}2.2 service类CommentService.java
/**
* service类
* @author wuKeFan
* @date 2023-02-20 16:55:23
*/
public interface CommentService {
List<Comment> getCommentByParentId(Long parentId);
void addComment(Comment comment);
Comment getById(Long id);
List<Comment> getList();
}2.3 service实现类CommentServiceImpl.java
/**
* @author wuKeFan
* @date 2023-02-20 16:56:00
*/
@Service
public class CommentServiceImpl implements CommentService{
@Resource
private CommentMapper baseMapper;
@Override
public List<Comment> getCommentByParentId(Long parentId) {
QueryWrapper<Comment> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("parent_id", parentId);
return baseMapper.selectList(queryWrapper);
}
@Override
public void addComment(Comment comment) {
baseMapper.insert(comment);
}
@Override
public Comment getById(Long id) {
return baseMapper.selectById(id);
}
@Override
public List<Comment> getList() {
return baseMapper.selectList(new QueryWrapper<Comment>().lambda().eq(Comment::getParentId, 0));
}
}2.4 数据库持久层类CommentMapper.java
/**
* mapper类
* @author wuKeFan
* @date 2023-02-20 16:53:59
*/
@Repository
public interface CommentMapper extends BaseMapper<Comment> {
}2.5 实体类Comment.java
/**
* 评论表实体类
* @author wuKeFan
* @date 2023-02-20 16:53:24
*/
@Data
@TableName("comment")
public class Comment {
@TableId(type = IdType.AUTO)
private Long id;
private Long parentId;
private String content;
private String author;
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date createTime;
}2.6 使用Postman请求接口,查看返回数据
2.6.1 请求评论列表接口(本地的url为:http://localhost:8081/one/comment/ ,GET请求),请求结果如图
2.6.2 根据评论id(或者回复id)返回回复列表(本地url为:http://localhost:8081/one/comment/parent/1 ,GET请求),请求结果如图
3 方案二
方案二采用的是将数据装到一个类似树的数据结构,然后返回,数据如果多的话,可以根据评论列表进行分页
3.1 控制层CommentTwoController.java
/**
* @author wuKeFan
* @date 2023-02-20 17:30:45
*/
@Slf4j
@RestController
@RequestMapping("/two/comment")
public class CommentTwoController {
@Resource
private CommentService commentService;
@GetMapping("/")
public List<CommentDTO> getAllComments() {
return commentService.getAllComments();
}
@PostMapping("/")
public void addComment(@RequestBody Comment comment) {
commentService.addComment(comment);
}
}3.2 service类CommentService.java
/**
* service类
* @author wuKeFan
* @date 2023-02-20 16:55:23
*/
public interface CommentService {
void addComment(Comment comment);
void setChildren(CommentDTO commentDTO);
List<CommentDTO> getAllComments();
}3.3 service实现类CommentServiceImpl.java
/**
* @author wuKeFan
* @date 2023-02-20 16:56:00
*/
@Service
public class CommentServiceImpl implements CommentService{
@Resource
private CommentMapper baseMapper;
@Override
public void addComment(Comment comment) {
baseMapper.insert(comment);
}
@Override
public List<CommentDTO> getAllComments() {
List<CommentDTO> rootComments = baseMapper.findByParentId(0L);
rootComments.forEach(this::setChildren);
return rootComments;
}
/**
* 递归获取
* @param commentDTO 参数
*/
@Override
public void setChildren(CommentDTO commentDTO){
List<CommentDTO> children = baseMapper.findByParentId(commentDTO.getId());
if (!children.isEmpty()) {
commentDTO.setChildren(children);
children.forEach(this::setChildren);
}
}
}3.4 数据库持久层类CommentMapper.java
/**
* mapper类
* @author wuKeFan
* @date 2023-02-20 16:53:59
*/
@Repository
public interface CommentMapper extends BaseMapper<Comment> {
@Select("SELECT id, parent_id as parentId, content, author, create_time as createTime FROM comment WHERE parent_id = #{parentId}")
List<CommentDTO> findByParentId(Long parentId);
}3.5 实体类CommentDTO.java
/**
* 递归方式实体类
* @author wuKeFan
* @date 2023-02-20 17:26:48
*/
@Data
public class CommentDTO {
private Long id;
private Long parentId;
private String content;
private String author;
private List<CommentDTO> children;
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date createTime;
}3.6 使用Postman请求接口,查看返回数据
3.6.1 通过递归的方式以树的数据结构返回(本地url为:http://localhost:8081/two/comment/ ,GET请求),请求结果如图
返回的json格式如图:
[
{
"id": 1,
"parentId": 0,
"content": "这是评论1",
"author": "吴名氏",
"children": [
{
"id": 2,
"parentId": 1,
"content": "我回复了第一条评论",
"author": "吴名氏",
"children": [
{
"id": 3,
"parentId": 2,
"content": "我回复了第一条评论的第一条回复",
"author": "吴名氏",
"children": [
{
"id": 6,
"parentId": 3,
"content": "我回复了第一条评论的第一条回复的第一条回复",
"author": "吴名氏",
"children": null,
"createTime": "2023-02-21 09:56:27"
}
],
"createTime": "2023-02-20 17:12:13"
},
{
"id": 4,
"parentId": 2,
"content": "我回复了第一条评论的第二条回复",
"author": "吴名氏",
"children": null,
"createTime": "2023-02-21 09:23:14"
}
],
"createTime": "2023-02-20 17:12:00"
}
],
"createTime": "2023-02-20 17:11:16"
},
{
"id": 5,
"parentId": 0,
"content": "这是评论2",
"author": "吴名氏",
"children": null,
"createTime": "2023-02-21 09:41:02"
}
]4 方案三
方案三是将所有数据用递归的SQL查出来,再把数据解析成树,返回结果,适合数据较少的情况下,且MySQL版本需要在8.0以上
4.1 控制层CommentThreeController.java
/**
* @author wuKeFan
* @date 2023-02-20 17:30:45
*/
@Slf4j
@RestController
@RequestMapping("/three/comment")
public class CommentThreeController {
@Resource
private CommentService commentService;
@GetMapping("/")
public List<CommentDTO> getAllCommentsBySql() {
return commentService.getAllCommentsBySql();
}
@PostMapping("/")
public void addComment(@RequestBody Comment comment) {
commentService.addComment(comment);
}
}4.2 service类CommentService.java
/**
* service类
* @author wuKeFan
* @date 2023-02-20 16:55:23
*/
public interface CommentService {
List<CommentDTO> getAllCommentsBySql();
}4.3 service实现类CommentServiceImpl.java
/**
* @author wuKeFan
* @date 2023-02-20 16:56:00
*/
@Service
public class CommentServiceImpl implements CommentService{
@Resource
private CommentMapper baseMapper;
/**
* 递归获取
* @param commentDTO 参数
*/
@Override
public void setChildren(CommentDTO commentDTO){
List<CommentDTO> children = baseMapper.findByParentId(commentDTO.getId());
if (!children.isEmpty()) {
commentDTO.setChildren(children);
children.forEach(this::setChildren);
}
}
}4.4 数据库持久层类CommentMapper.java
/**
* mapper类
* @author wuKeFan
* @date 2023-02-20 16:53:59
*/
@Repository
public interface CommentMapper extends BaseMapper<Comment> {
@DS("localhost80")
List<CommentDTO> getAllCommentsBySql();
}4.5 实体类Comment.java
/**
* 评论表实体类
* @author wuKeFan
* @date 2023-02-20 16:53:24
*/
@Data
@TableName("comment")
public class Comment {
@TableId(type = IdType.AUTO)
private Long id;
private Long parentId;
private String content;
private String author;
@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
private Date createTime;
private Integer level;
}4.6 使用Postman请求接口,查看返回数据
4.6.1 通过递归的方式以树的数据结构返回(本地url为:http://localhost:8081/three/comment/ ,GET请求),请求结果如图
返回的json格式如图:
[
{
"id": 1,
"parentId": 0,
"content": "这是评论1",
"author": "吴名氏",
"children": [
{
"id": 2,
"parentId": 1,
"content": "我回复了第一条评论",
"author": "吴名氏",
"children": [
{
"id": 3,
"parentId": 2,
"content": "我回复了第一条评论的第一条回复",
"author": "吴名氏",
"children": [
{
"id": 6,
"parentId": 3,
"content": "我回复了第一条评论的第一条回复的第一条回复",
"author": "吴名氏",
"children": [],
"createTime": "2023-02-21 09:56:27",
"level": 4
}
],
"createTime": "2023-02-20 17:12:13",
"level": 3
},
{
"id": 4,
"parentId": 2,
"content": "我回复了第一条评论的第二条回复",
"author": "吴名氏",
"children": [],
"createTime": "2023-02-21 09:23:14",
"level": 3
}
],
"createTime": "2023-02-20 17:12:00",
"level": 2
}
],
"createTime": "2023-02-20 17:11:16",
"level": 1
},
{
"id": 5,
"parentId": 0,
"content": "这是评论2",
"author": "吴名氏",
"children": [],
"createTime": "2023-02-21 09:41:02",
"level": 1
}
]