QueryDSL+Spring Data JPA简单动态查询

左手的ㄟ右手 2022-12-13 04:11 262阅读 0赞

## 1.Repository类继承QuerydslPredicateExecutor ##

package com.supcon.oms.repository;
    
    import com.supcon.oms.entity.TTankEntity;
    import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
    import org.springframework.data.jpa.repository.Query;
    import org.springframework.data.querydsl.QuerydslPredicateExecutor;
    import org.springframework.data.repository.PagingAndSortingRepository;
    import org.springframework.data.repository.query.Param;
    
    /**
     * @author: zhaoxu
     * @date: 2020/8/28 9:08
     */
    public interface TankManageRepository extends JpaSpecificationExecutor<TTankEntity>,PagingAndSortingRepository<TTankEntity,Integer>, QuerydslPredicateExecutor<TTankEntity> { 
        /**获取数据库中Id最大的值
         *
         * @return
         */
        @Query("select max(tank.tankId) from TTankEntity tank order by tank.tankId desc")
        String getMaxId();
    
        /**
         * 通过Id获取tank实体
         * @param tankId
         * @return
         */
        @Query("select tank from TTankEntity tank where tank.tankId = :tankId")
        TTankEntity findTankById(@Param("tankId") Integer tankId);
    
    }

## 2.修改pom文件 ##

**2.1添加pom依赖**

<dependency>
                <groupId>com.querydsl</groupId>
                <artifactId>querydsl-jpa</artifactId>
                <version>${querydsl.version}</version>
            </dependency>
            <dependency>
                <groupId>com.querydsl</groupId>
                <artifactId>querydsl-apt</artifactId>
                <version>${querydsl.version}</version>
                <scope>provided</scope>
            </dependency>

**2.2添加Maven插件**

<plugin>
                    <groupId>com.mysema.maven</groupId>
                    <artifactId>apt-maven-plugin</artifactId>
                    <version>1.1.3</version>
                    <executions>
                        <execution>
                            <goals>
                                <goal>process</goal>
                            </goals>
                            <configuration>
                                <outputDirectory>target/generated-sources/java</outputDirectory>
                                <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                            </configuration>
                        </execution>
                    </executions>
                </plugin>

## 3.生成Q实体类，点击右侧Maven->compile，运行compile自动生成Q实体类，将Q实体类复制到项目当中 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70_pic_center]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70_pic_center 1]

## 4.QueryDSL简单动态查询 ##

@Autowired
        TankManageRepository tankManage;
    
        @Autowired
        EntityManager entityManager;
    
        @Autowired
        BaseConverter baseConverter;
    
        JPAQueryFactory jpaQueryFactory;
    
        @PostConstruct
        public void initFactory() { 
            jpaQueryFactory = new JPAQueryFactory(entityManager);
        }
    
        @Override
        public Map<String, Object> findTanks(Map<String, String> tableMap) { 
            int current = Integer.valueOf(tableMap.get("current"));
            int pageSize = Integer.valueOf(tableMap.get("pageSize"));
            String tankNameJson = "tankName";
            String tankNoJson = "tankNo";
            String tankFarmidJson = "tankFarmid";
            Sort sort = new Sort(Sort.Direction.ASC, "tankNo");
            Pageable pageable = PageRequest.of(current - 1, pageSize, sort);
            QTTankEntity qtTankEntity = QTTankEntity.tTankEntity;
            List<TTankEntity> tankList = jpaQueryFactory.select(qtTankEntity)
                    .from(qtTankEntity)
                    .where(qtTankEntity.tankNo.like("%1%").and(qtTankEntity.tankFarmid.like("%1%")))
                    .limit(current)
                    .offset((current - 1) * pageSize + pageSize)
                    .fetch();
            return baseConverter.convertMultiObjectToMap(new PageImpl(tankList),TTankVo.class);
        }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/593459524a4749239cc5a55834451049.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM5ODk4MTkx_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/fbc847d509e34a4787d0960f014ca712.png