SpringDataJPA

环境

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!--用于复杂查询-->
<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-jpa</artifactId>
</dependency>
<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-sql</artifactId>
</dependency>
<dependency>
    <groupId>com.querydsl</groupId>
    <artifactId>querydsl-apt</artifactId>
</dependency>

<build>
<plugins>
    <plugin>
        <groupId>com.mysema.maven</groupId>
        <artifactId>apt-maven-plugin</artifactId>
        <version>1.1.3</version>
        <executions>
            <execution>
                <goals>
                    <goal>process</goal>
                </goals>
                <configuration>
                    <!-- q类实体生成地址-->
                    <outputDirectory>target/generated-sources/java</outputDirectory>
                    <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                </configuration>
            </execution>
        </executions>
    </plugin>
</plugins>
</build>

实现JpaRepository对象用于简单查询

public interface SysUserRepository extends JpaRepository<SysUser, Long> {
    
}

常用注解

• @Data
• @MappedSuperclass
• @Id
• @GeneratedValue(strategy = GenerationType.IDENTITY)
• @Column
• @Transient
• @Query:支持jpql查询，nativeQuery=true时使用sql查询

// 自定义dto接口
public interface PeopleDTO {    
    String getName();
    Long getCount();    
}
// jpa代理对象可以直接json化返回前端
@Query(value = "SELECT p.name AS name, COUNT(dp.people_id) AS count " +
               "FROM people p INNER JOIN dream_people dp " +
               "ON p.id = dp.people_id " +
               "WHERE p.user_id = :userId " +
               "GROUP BY dp.people_id " +
               "ORDER BY p.name", nativeQuery = true)
List<PeopleDTO> findByPeopleAndCountByUserId(@Param("userId") Long userId);

简单查询api

• findOne(id)：根据id查询
• findAll(): 查询全部
• findAllById(List<> ids):查询所有id
• save(customer):保存或者更新
• delete(id)：根据id删除
• count()：统计总条数

方法名称规则查询

public interface SysUserRepository extends JpaRepository<SysUser, Long> {
    Page<SysRole> findByName(String name, Pageable page);
}

方法名称规则

注入JPAQueryFactory对象用于复杂查询

@Bean
public JPAQueryFactory jpaQueryFactory(EntityManager entityManager) {
        return new JPAQueryFactory(entityManager);
}

public List<SysRole> listRolesByUserId(Long userId) {
        return jpaQueryFactory.selectFrom(qSysRole)
        .leftJoin(qSysUserRole).on(qSysRole.id.eq(qSysUserRole.roleId))
        .where(qSysUserRole.userId.eq(userId)).fetch();
        }