条件查询

标签查询

1. POST /label/search 根据条件查询列表
   (1)labelService中增加方法

/*
*  构建查询条件
*/
private Specification<Label> createSpecification(Map searchMap){
  return new Specification<Label>(){
     @Override         public Predicate toPredicate(Root<Label> root, CriteriaQuery<?>  criteriaQuery, CriteriaBuilder cb) {             List<Predicate> predicateList=new ArrayList<>();             if(searchMap.get("labelname")!=null &&  !"".equals(searchMap.get("labelname"))){          
       predicateList.add(cb.like(  root.get("labelname").as(String.class), "%"+ (String)searchMap.get("labelname")+"%"  ) );      
       }        
     if(searchMap.get("state")!=null &&  !"".equals(searchMap.get("state"))){                 predicateList.add(cb.equal(  root.get("state").as(String.class), (String)searchMap.get("state") ) );      
       }            
 if(searchMap.get("recommend")!=null && !"".equals(searchMap.get("recommend"))){           
      predicateList.add(cb.equal(  root.get("recommend").as(String.class),  (String)searchMap.get("recommend") ) );         
    } 
  }
}

(2).LabelController

/*
*  根据条件查询
* @param searchMap
* @return 
*/
@RequestMapping(value = "/search",method = RequestMethod.POST)
public Result<List> findSearch(@RequestBody Map searchMap){
  return new Result<>(true,StatusCode.OK,"查询成功",labelService.findSearch(searchMap));
}

带分页的条件查询

(1)修改labelService，增加方法

/*
*  带分页的条件查询
* @Param searchMap
* @Param page
* @param size
* @return
*/
public Page<Label> findSearch(Map searchMap,int page,int size){
  Specification specification = createSpecification(searchMap);
  PageRequest pageRequest = PageRequest.of(page-1,size);
  return labelDao.findAll(specification,pageRequest);
}

(2)修改labelController

/*
*  条件+分页查询
* @Param searchMap
* @Param page
* @Param size
* @return
*/
@RequestMapping(value = "/search/{page}/{size}",method = RequestMethod.POST)
  public Result<List> findSeach(@RequestBody Map searchMap,@PathVariable int page,@PathVariable int size){
  Page pageList = labelService.findSearch(searchMap,page,size);
  return new Result(true,StatusCode.OK,"查询成功",new PageResult<>(pageList.getTotalElements(),pageList.getContent()));
}

问答微服务开发

表结构分析

问题表

image.png

回答表

image.png

问答标签中间表

image.png

实体类

@Entity
@Table(name = "tb_pl")
public class Pl implements Serializable{
  @Id
  private String problemid;
  
  @Id
  private String labelid;

  //setters/getters...
}

Dao层增加方法

/*
*根据标签ID查询最新问题列表
*@Param labelId
*@Param pageable
*@return 
*/
@Query("select p from Problem p where id in(select problemid from P1 where labelid = ?1) order by replytime desc")
public Page<Problem> findNewestListByLabelId(String labelId,Pageable pageable);

Service层增加方法

/*
*  根据标签ID查询问题列表
*@Param labelId 标签ID
*@Param page 页码
*@Param size 页大小
*@return
*/
public Page<Problem> findNewestListByLabelId(String labelId,int page,int size){
  PageRequest pageRequest = PageRequest.of(page-1,size);
  return problemDao.findNewListByLabelId(labelId,pageRequest);
}

ProblemController新增方法

/*
*@Param labelId 标签ID
*@return
*/
@RequestMapping(value="/newlist/{labelid}/{page}/{size}",method=RequestMe thod.GET)      
public Result findNewListByLabelId(@PathVariable String labelid,@PathVariable int page,@PathVariable int size ){   
  Page<Problem> pageList = problemService.findNewListByLabelId(labelid, page, size);        
  PageResult<Problem> pageResult = new PageResult<> (pageList.getTotalElements(), pageList.getContent());                  
   return  new Result(true, StatusCode.OK, "查询成功",pageResult); 
       }

缓存处理

为了提高查询的性能，我们通常采用Redis缓存解决。

SpringDataRedis

Spring-Data-Redis是spring大家族的一部分，提供了在spring应用中通过简单的配置访问redis服务，对redis底层开发包进行了高度封装，RedisTemplate

配置

(1)在pom.xml中引入依赖

<dependency>
<groupId>org.springframework.boot</groupId>               
<artifactId>spring‐boot‐starter‐data‐redis</artifactId>              </dependency>  

(2)修改application.yml,在spring节点下添加配置

redis:
  host:192.168.184.134  

(3)修改Service层，引入RedisTemplate，并修改方法

@Autowired
private RedisTemplate redisTemplate;

/*
*  根据Id查询实体
*/
public Article findById(String id){
  //从缓存中提取
  Article article = (Article)redisTemplate.opsForValue().get("article_"+id);
  //如果缓存中没有，则到数据库查询并放入缓存
  if(article == null){
    article  = articleDao.findById(id).get();
    redisTemplate.opsForValue().set("article_" + id,article);
  }
  return article;
}

(4)修改或者删除后清空缓存

/*
*  修改
*  @param article
*/
public void update(Article article){
  redisTemplate.delete("article_" + article.getId());
  articleDao.save(article);
}

/*
*  删除
*  @Param id
*/
public void deleteById(String id){
  redisTemplate.delete("article" + id);  //删除缓存
  articleDao.deleteById(id);
}

缓存过期处理

修改findById方法，设置1天的过期时间

redisTemplate.opsForValue().set("article_" + id,article,1,TimeUnit.DAYS);