SpringDataJPA是Spring基于ORM框架、JPA规范的基础上封装的一套JPA应用框架，底层使用了Hibernate的JPA技术实现。提供了基本CRUD操作。能够满足日常开发过程中对数据库访问的日常需求。特殊的查询还可以自定义查询语句。极简的配置就可以使用起来，极大的减少了开发者的负担。
下面通过一个简单的案例讲述如何使用。
引入jar. <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> Spring Boot 入口类上添加@EnableJpaAuditing注解，用于自动创建表。application.yml文件中做下配置。 spring: application: name: tourist jpa: # print sql or not show-sql: false open-in-view: false hibernate: # 开启自动建表功能，一般选update，每次启动会对比实体和数据表结构是否相同，不相同会更新 ddl-auto: update naming-strategy: org.springframework.boot.orm.jpa.hibernate.SpringNamingStrategy # 设置创表引擎为Innodb，不然默认为MyiSam database-platform: org.hibernate.dialect.MySQL5InnoDBDialect datasource: url: jdbc:mysql://localhost:3306/tourist?useUnicode=true&characterEncoding=utf8&useSSL=false&serverTimezone=UTC name: username: root password: driver-class-name: com.mysql.cj.jdbc.Driver type: com.zaxxer.hikari.HikariDataSource hikari: data-source-properties: cachePrepStmts: true prepStmtCacheSize: 250 prepStmtCacheSqlLimit: 2048 useServerPrepStmts: true 新建一个Entity. @SuppressWarnings("serial") @MappedSuperclass @Data public abstract class AbstractEntity implements Serializable { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "created_date", columnDefinition = "datetime") @CreatedDate private Date createdDate; @Column(name = "update_date", columnDefinition = "datetime") @LastModifiedDate private Date updateDate; } import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.EntityListeners; import javax.persistence.Table; import javax.validation.constraints.NotNull; import org.springframework.data.jpa.domain.support.AuditingEntityListener; import lombok.AllArgsConstructor; import lombok.Data; import lombok.EqualsAndHashCode; import lombok.NoArgsConstructor; @SuppressWarnings("serial") @Entity @Data @EqualsAndHashCode(callSuper = false) @NoArgsConstructor @AllArgsConstructor @Table(name = "user") @EntityListeners(AuditingEntityListener.class) public class User extends AbstractEntity { @NotNull @Column(name = "name", columnDefinition = "varchar(10) not null comment '用户名'") private String name; @Column(name = "age", columnDefinition = "tinyint(1) not null comment '年龄'") private Integer age; @Column(name = "password", columnDefinition = "varchar(60) not null comment '密码'") private String password; @NotNull @Column(name = "phone_number", columnDefinition = "varchar(11) not null comment '手机号'", unique = true) private String phoneNumber; } 定义持久层.根目录下新建一个package:repository /** * Spring Data JPA repository for the User entity. */ public interface UserRepository extends JpaRepository<User, Long> { User findByPhoneNumber(String phoneNumber); }定义Service层。 @Service @Slf4j public class UserService { @Inject private UserMapper userMapper; @Inject private UserRepository userRepository; public UserDto findOne(Long id) { log.debug("get entity by id [{}]", id); return userMapper.entityToDto(userRepository.findById(id).get(), null); } public UserDto create(UserDto dto) { log.debug("create user [{}]", dto); User userDb = userRepository.findByPhoneNumber(dto.getPhoneNumber()); if (userDb == null) { return userMapper.entityToDto(userRepository.save(userMapper.dtoToEntity(dto, null)), null); } return userMapper.entityToDto(userDb, null); } public void delete(Long id) { log.debug("delete user by id [{}]", id); userRepository.deleteById(id); } public UserDto update(UserDto dto) { log.debug("update user [{}]", dto); return userMapper.entityToDto(userRepository.save(userMapper.dtoToEntity(dto, null)), null); } } 附：mapper 类： public abstract class DeepflowAbstractMapper<E extends AbstractEntity, D extends DeepflowAbstractDto> { protected final Class<E> entityClazz; protected final Class<D> dtoClazz; @SuppressWarnings("unchecked") public DeepflowAbstractMapper() { Class<?>[] genericTypes = GenericTypeResolver.resolveTypeArguments(getClass(), DeepflowAbstractMapper.class); this.entityClazz = (Class<E>) genericTypes[0]; this.dtoClazz = (Class<D>) genericTypes[1]; } public E dtoToEntity(D dto, String... ignoreProperties) { if (dto == null) return null; E entity = BeanUtils.instantiateClass(this.entityClazz); copyPropertiesFromDto(dto, entity, ignoreProperties); return entity; } public D entityToDto(E entity, String... ignoreProperties) { if (entity == null) return null; D dto = BeanUtils.instantiateClass(this.dtoClazz); copyPropertiesFromEntity(entity, dto, ignoreProperties); return dto; } // override if necessary protected void copyPropertiesFromEntity(E source, D target, String... ignoreProperties) { BeanUtils.copyProperties(source, target, ignoreProperties); } // override if necessary public void copyPropertiesFromDto(D source, E target, String... ignoreProperties) { BeanUtils.copyProperties(source, target, ignoreProperties); } } @Component public class UserMapper extends DeepflowAbstractMapper<User, UserDto> { }
定义controller层方法。 @RestController @RequestMapping("/users") public class UserController { @Inject private UserService userService; @GetMapping("/{id}") public UserDto getUser(@PathVariable Long id) { return userService.findOne(id); } @PostMapping() public UserDto create(@RequestBody UserDto userDto) { return userService.create(userDto); } @PutMapping() public UserDto update(@RequestBody UserDto userDto) { return userService.update(userDto); } }
八．测试
在启动项目前，先在数据库里新建一个库：tourist。然后启动项目后，到数据库会发现，数据库里应自动生成里相应的表和字段。可以使用postman去调用户接口。
