得到标签下的问答列表

src/main/java/cn/meteor/beyondclouds/modules/question/api/QuestionApi.java

@@ -255,5 +255,18 @@ public class QuestionApi {
         return Response.success(questionPageVO);
     }
 
+    @Anonymous
+    @ApiOperation("标签下的问答列表")
+    @GetMapping("/tag/{tagId}/questions")
+    public Response<PageVO<Question>> getQuestionsByTagId(@Valid PageForm pageForm, @PathVariable("tagId") String tagId) {
+        try {
+            IPage<Question> page = questionService.getQuestionsByTagId(pageForm.getPage(), pageForm.getSize(), tagId);
+            PageVO<Question> pageVO = new PageVO<>(page);
+            return Response.success(pageVO);
+        } catch (QuestionTagServiceException e) {
+            e.printStackTrace();
+            return Response.error(e);
+        }
+    }
 
 }

src/main/java/cn/meteor/beyondclouds/modules/question/enums/QuestionTagErrorCode.java

@@ -7,7 +7,10 @@ import cn.meteor.beyondclouds.core.IErrorCode;
  * @since 2020/2/1
  */
 public enum QuestionTagErrorCode implements IErrorCode {
-    ;
+    /**
+     * 标签不存在
+     */
+    TAG_NOT_FOUND(6001, "标签不存在");
 
     private long code;
     private String msg;

src/main/java/cn/meteor/beyondclouds/modules/question/service/IQuestionService.java

@@ -93,4 +93,14 @@ public interface IQuestionService extends IService<Question> {
      */
     IPage<Question> getHotsQuestionsPage(Integer pageNumber, Integer pageSize);
 
+    /**
+     * 得到标签下的问答列表
+     * @param pageNumber 页数
+     * @param pageSize 页面大小
+     * @param tagId 标签ID
+     * @return 分页对象
+     * @throws QuestionTagServiceException 问题标签业务异常
+     */
+    IPage<Question> getQuestionsByTagId(Integer pageNumber, Integer pageSize, String tagId) throws QuestionTagServiceException;
+
 }

src/main/java/cn/meteor/beyondclouds/modules/question/service/impl/QuestionServiceImpl.java

@@ -3,6 +3,7 @@ package cn.meteor.beyondclouds.modules.question.service.impl;
 import cn.meteor.beyondclouds.modules.question.bean.QuestionDetails;
 import cn.meteor.beyondclouds.modules.question.entity.*;
 import cn.meteor.beyondclouds.modules.question.enums.QuestionErrorCode;
+import cn.meteor.beyondclouds.modules.question.enums.QuestionTagErrorCode;
 import cn.meteor.beyondclouds.modules.question.exception.QuestionServiceException;
 import cn.meteor.beyondclouds.modules.question.exception.QuestionTagServiceException;
 import cn.meteor.beyondclouds.modules.question.mapper.QuestionMapper;
@@ -418,4 +419,27 @@ public class QuestionServiceImpl extends ServiceImpl<QuestionMapper, Question> i
         questionTagService.remove(questionTagQueryWrapper);
     }
 
+    @Override
+    public IPage<Question> getQuestionsByTagId(Integer pageNumber, Integer pageSize, String tagId) throws QuestionTagServiceException {
+        IPage<Question> page = new Page<>(pageNumber, pageSize);
+
+        //1.检查标签是否存在
+        Tag tag = tagService.getById(tagId);
+        if (null == tag) {
+            throw new QuestionTagServiceException(QuestionTagErrorCode.TAG_NOT_FOUND);
+        }
+
+        //2.通过标签ID得到对应的问题ID
+        List<String> questionIds = questionTagService.list(QuestionUtils.getWrapper("tag_id", tag.getTagId()))
+                                                     .stream().map(QuestionTag::getQuestionId).collect(Collectors.toList());
+
+        if (!CollectionUtils.isEmpty(questionIds)) {
+            QueryWrapper<Question> questionQueryWrapper = new QueryWrapper<>();
+            questionQueryWrapper.in("q.question_id", questionIds)
+                                .orderByDesc("q.create_time");
+            return questionMapper.selectPageWithTags(page, questionQueryWrapper);
+        }else {
+            return page;
+        }
+    }
 }

src/main/resources/application.yml

@@ -3,7 +3,7 @@ spring:
     driver-class-name: com.mysql.cj.jdbc.Driver
     url: jdbc:mysql://127.0.0.1:3306/beyond_clouds?useUnicode=true&characterEncoding=UTF-8&useSSL=false&allowPublicKeyRetrieval=true
     username: root
-    password: 100Centa30821%mysql
+    password: 197442
   mail:
     host: smtp.163.com
     username: 13546386889@163.com