SpringDataJPA使用
一、简介
SpringDataJpa是 JPA规范的一个很好的实现,简化了开发的复杂度,极大提升了开发的效率。SpringDataJpa通过 Repository接口及子接口可以很方便的实现持久化操作。
SpringDataJpa的API在线手册:https://docs.spring.io/spring-data/jpa/docs/2.1.0.RELEASE/api/
简单的看下 Repository 类层次结构图关系:
Repository:空的父接口,即是一个标记接口。
CrudRepository:Repository的子接口,提供CRUD操作
PagingAndSortingRepository:CrudRepository的子接口,增加 分页 和 排序的功能
JpaRepository:PagingAndSortingRepository、QueryByExampleExecutor的子接口,增加 批量操作 以及 QBE查询
SimpleJpaRepository:实现了JpaRepository 和 JpaSpecificationExecutor 接口,构造函数中传入 EntityManager。类上注解了@Transactional(readOnly = true),对于CUD的方法使用了注解@Transactional,局部有限原则。各种方法最终的实现都依托于 EntityManager来完成。
二、使用
1、创建springboot项目 springdata-jpa
2、src/main/resources 目录下新建 application.properties,内容如下:
db.driverClass=com.mysql.jdbc.Driver db.jdbcUrl=jdbc:mysql://localhost:3310/boot?useUnicode=true&characterEncoding=UTF-8&useSSL=false db.username=root db.password=123456 spring.jpa.properties.hibernate.show_sql=true spring.jpa.properties.hibernate.format_sql=true #修改实体类的匹配命名规则,主要影响@column(name="")配置,默认是驼峰匹配法 spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
3、创建 DataSource configuration:
package com.cfang.confingurations; import javax.sql.DataSource; import org.springframework.beans.factory.annotation.Value; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import com.alibaba.druid.pool.DruidDataSource; @Configuration public class DataSourceConfigurations { @Value("${db.driverClass:com.mysql.jdbc.Driver}") private String driverClass; @Value("${db.jdbcUrl}") private String jdbcUrl; @Value("${db.username}") private String username; @Value("${db.password}") private String password; @Value("${initialSize:10}") private Integer initialSize; //初始化连接池个数 @Value("${maxActive:20}") private Integer maxActive; //最大连接数 @Value("${maxWait:60000}") private Long maxWait; //获取连接等待超时时间,单位毫秒 @Value("${timeBetweenEvictionRunsMillis:60000}") private Long timeBetweenEvictionRunsMillis; //间隔多久进行一次检测,检测回收需要关闭的空闲链接,单位毫秒 @Value("${minEvictableIdleTimeMillis:300000}") private Long minEvictableIdleTimeMillis; //定义一个连接在池中的最小生存时间,单位毫秒 @Value("${validationQuery:select 1 from dual}") private String validationQuery; //用来检测连接是否有效的sql @Value("${testWhileIdle:true}") private Boolean testWhileIdle; //申请连接的时候是否检测。如果空间时间大于timeBetweenEvictionRunsMillis,执行validationQuery检测连接是否有效 @Value("${testOnBorrow:false}") private Boolean testOnBorrow; @Value("${testOnReturn:false}") private Boolean testOnReturn; //归还连接的时候,是否validationQuery检查连接的有效性,true执行的话,降低性能 @Value("${poolPreparedStatements:false}") private Boolean poolPreparedStatements; //是否打开pscache @Value("${maxPoolPreparedStatementPerConnectionSize:20}") private int maxPoolPreparedStatementPerConnectionSize; //指定每个连接的pscache的大小 @Bean public DataSource initDataSource() { DruidDataSource dataSource = new DruidDataSource(); dataSource.setDriverClassName(driverClass); dataSource.setUrl(jdbcUrl); dataSource.setUsername(username); dataSource.setPassword(password); dataSource.setInitialSize(initialSize); dataSource.setMaxActive(maxActive); dataSource.setMaxWait(maxWait); dataSource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis); dataSource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis); dataSource.setValidationQuery(validationQuery); dataSource.setTestWhileIdle(testWhileIdle); dataSource.setTestOnBorrow(testOnBorrow); dataSource.setTestOnReturn(testOnReturn); dataSource.setPoolPreparedStatements(poolPreparedStatements); if(poolPreparedStatements) { dataSource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize); } return dataSource; } }
4、创建User实体
package com.cfang.entity; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import lombok.Data; @Entity @Table(name = "tb_user") @Data public class TblUserEntity { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "id") private int id; @Column(name = "name") private String name; @Column(name = "password") private String password; @Column(name = "age") private int age; }
5、创建持久化操作Repository:
package com.cfang.repository; import java.util.List; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.repository.JpaRepository; import org.springframework.data.jpa.repository.JpaSpecificationExecutor; import org.springframework.data.jpa.repository.Modifying; import org.springframework.data.jpa.repository.Query; import org.springframework.data.repository.query.Param; import com.cfang.entity.TblUserEntity; public interface UserRepository extends JpaRepository<TblUserEntity, Integer>, JpaSpecificationExecutor<TblUserEntity>{ /** * springdata关键字命名方法,可不写实现 */ TblUserEntity findByName(String name); TblUserEntity findByNameAndAge(String name, int age); List<TblUserEntity> findByNameLikeAndAge(String name, int age); Page<TblUserEntity> findUserPageByNameLike(String name, Pageable pageable); /** * JPQL */ @Query(value = "from TblUserEntity where id=?1", nativeQuery = false) TblUserEntity readIdByJPQL(int id); @Query(value = "select * from tb_user where id=:id", nativeQuery = true) TblUserEntity readIdBySQL(int id); @Modifying @Query(value = "update TblUserEntity set name=?2 where id=?1", nativeQuery = false) int updateUserNameByIdJPQL(int id, String name); @Modifying @Query(value = "update tb_user set name=:name where id=:id", nativeQuery = true) int updateUserNameByIdSQL(@Param("id")int id, @Param("name")String name); @Query(value = "from TblUserEntity where name like %?1%", nativeQuery = false) List<TblUserEntity> findUserByNameJPQL(String name); @Query(value = "select * from tb_user where name like %:name%", nativeQuery = true) List<TblUserEntity> findUserByNameSQL(String name); }
6、创建 junit 测试
package com.cfang.repository; import java.util.List; import javax.persistence.criteria.CriteriaBuilder; import javax.persistence.criteria.CriteriaQuery; import javax.persistence.criteria.Predicate; import javax.persistence.criteria.Root; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageRequest; import org.springframework.data.domain.Pageable; import org.springframework.data.domain.Sort; import org.springframework.data.jpa.domain.Specification; import org.springframework.test.annotation.Rollback; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import org.springframework.test.context.web.WebAppConfiguration; import org.springframework.transaction.annotation.Transactional; import com.alibaba.fastjson.JSON; import com.cfang.SpringDataJpaApplication; import com.cfang.entity.TblUserEntity; import com.google.common.collect.Lists; import lombok.extern.slf4j.Slf4j; @Slf4j @RunWith(SpringJUnit4ClassRunner.class) @SpringBootTest(classes = {SpringDataJpaApplication.class}) @WebAppConfiguration public class UserTest { @Autowired private UserRepository userRepository; @Test public void findByName() { TblUserEntity entity = userRepository.findByName("lisi"); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void findByNameAndAge() { TblUserEntity entity = userRepository.findByNameAndAge("lisi", 22); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void findByNameLikeAndAge() { List<TblUserEntity> entity = userRepository.findByNameLikeAndAge("li%", 22); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void readIdByJPQL() { TblUserEntity entity = userRepository.readIdByJPQL(27); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void readIdBySQL() { TblUserEntity entity = userRepository.readIdBySQL(27); log.info("result:{}", JSON.toJSONString(entity)); } @Test @Transactional @Rollback(false) public void updateUserNameByIdJPQL() { int result = userRepository.updateUserNameByIdJPQL(27, "wangwu"); log.info("result:{}", result); } @Test @Transactional @Rollback(false) public void updateUserNameByIdSQL() { int result = userRepository.updateUserNameByIdSQL(27, "wangwu2"); log.info("result:{}", result); } @Test public void findUserByNameJPQL() { List<TblUserEntity> entity = userRepository.findUserByNameJPQL("li"); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void findUserByNameSQL() { List<TblUserEntity> entity = userRepository.findUserByNameSQL("li"); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void findUserPageByNameLike() { Pageable pageable = PageRequest.of(0, 2, new Sort(Sort.Direction.DESC, "id")); Page<TblUserEntity> entity = userRepository.findUserPageByNameLike("li%", pageable); log.info("result:{}", JSON.toJSONString(entity)); } @Test public void testSpecification() { Pageable pageable = PageRequest.of(0, 2, Sort.Direction.DESC, "id"); String name = "li"; Specification<TblUserEntity> specification = new Specification<TblUserEntity>() { @Override public Predicate toPredicate(Root<TblUserEntity> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) { List<Predicate> conditions = Lists.newArrayList(); Predicate condition = null; condition = criteriaBuilder.like(root.get("name"), "%" + name + "%"); conditions.add(condition); condition = criteriaBuilder.greaterThan(root.get("id"), 27); conditions.add(condition); Predicate[] arr = new Predicate[conditions.size()]; // return criteriaBuilder.and(conditions.toArray(arr)); query.where(conditions.toArray(arr)); return null; } }; Page<TblUserEntity> result = userRepository.findAll(specification, pageable); log.info("result:{}", JSON.toJSONString(result)); } }
ps:在进行 repository 的CUD操作的时候,必须加事务支持 @Transactional,否则会报错(截取部分出错信息):
org.springframework.dao.InvalidDataAccessApiUsageException: Executing an update/delete query; nested exception is javax.persistence.TransactionRequiredException: Executing an update/delete query
Caused by: javax.persistence.TransactionRequiredException: Executing an update/delete query
三、总结
数据进行持久化操作的时候,都是需要一个对象来进行相关操作的,原生的Hibernate中使用Session,JPA中使用EntityManager,MyBatis中使用SqlSession。上述工程中,在主类main方法中可添加如下进行查看:
@Bean public Object testTransactionManager(PlatformTransactionManager manager) { System.out.println("TransactionManager is : " + manager.getClass().getName()); return new Object(); }
SpringDataJpa提供了丰富的CRUD构造的方法,具体可根据实际情况查询使用。