2.springboot配置jpa

1.pom依赖引入

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

2.application.properties配置文件

server.port=8080
server.servlet.context-path=/jpalogging.level.com.yuchen.VOS.dao=debug
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver#配置mysql8.0,阿里连接池需要引入区域信息才能启动
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url=jdbc:mysql://abc.com:3306/springboot_jpa_demo?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Chongqing
spring.datasource.username=root
spring.datasource.password=123456#阿里druid连接池驱动配置信息
#初始化大小，最小，最大
spring.datasource.initialSize=2
spring.datasource.minIdle=2
spring.datasource.maxActive=15
#配置获取连接等待超时的时间
spring.datasource.maxWait=5000
#配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
#配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
#打开PSCache，并且指定每个连接上PSCache的大小
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20#配置阿里数据源的扩展过滤器
#WallFilter：Druid防御SQL注入攻击的防火墙，会在jdbc底层执行时对sql语句进行审查，防止sql注入，并支持mysql，orcale等数据库的语法
#statFilter：开启监控界面的sql统计
spring.datasource.filters=stat,wall,log4j
#通过connectProperties属性来打开mergeSql功能；慢SQL记录
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000# JPA配置，驼峰命名是自动的
spring.jpa.database = MYSQL# 是否将执行的sql语句显示到控制台,正式环境建议关闭
spring.jpa.show-sql = true# Hibernate ddl auto 参数用来配置是否开启自动更新数据库表结构，可取create、create-drop、update、validate、none五个值
#create 每次加载hibernate时，先删除已存在的数据库表结构再重新生成；
#create-drop 每次加载hibernate时，先删除已存在的数据库表结构再重新生成，当sessionFactory关闭时也会先删除已存在的数据库表结构再重新生成
#update 只在第一次加载hibernate时自动生成数据库表结构，以后再次加载hibernate时根据model类自动更新表结构；
#validate 每次加载hibernate时，验证数据库表结构，只会和数据库中的表进行比较，不会创建新表，但是会插入新值。
#none 什么都不做
spring.jpa.hibernate.ddl-auto = update# Naming strategy
#[org.hibernate.cfg.ImprovedNamingStrategy  #org.hibernate.cfg.DefaultNamingStrategy]
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy#设置Hibernate使用的数据库方言
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

3.定义实体类

@Entity //用来标记该类是一个JPA实体类
@Table(name = "ums_user") //映射数据库表,name为数据库的表名
public class User implements Serializable {private static final long serialVersionUID = -679176727475076780L;@Id //定义记录的唯一标识@GeneratedValue(strategy = GenerationType.AUTO) //定义记录的生成规则private Long id;private String username;private String password;private String nickName;private Integer level;@Transient  //表示该字段不和数据库字段关联private Integer status;private Integer isDelete;@Column(name = "create_time", columnDefinition = "DATETIME")private Date createTime;@Column(nullable = true, columnDefinition = "decimal(11,2)")private BigDecimal tradeTotalMoney;//get、set省略
}

4.dao层继承 Repository<实体类型,主键id的类型>

public interface UserDao extends JpaRepository<User,Long> {//如果需要自己写sql，使用Query即可,@Query("select e.id as employeeId,e.name as employeeName,d.id as departmentId,d.name as departmentName from Employee e , Department d where e.id= ?1 and d.id= ?2")EmployeeDetail getEmployeeJoinDepartment(Long eid, Long did);
}

5.service层与实现类

public interface UserService {User save(User user);boolean delete(Long id);boolean update(User user);List<User> listAll();Page<User> list(Integer pageNo,Integer pageSize);User getUser(Long id);
}

@Service
public class UserServiceImpl implements UserService {@Autowiredprivate UserDao userDao;@Overridepublic User save(User user) {User save = userDao.save(user);return save;}@Overridepublic boolean delete(Long id) {userDao.deleteById(id);return false;}@Overridepublic boolean update(User user) {User save = userDao.save(user);return false;}@Overridepublic List<User> listAll() {return userDao.findAll();}@Overridepublic Page<User> list(Integer pageNo, Integer pageSize) {Pageable pageable = PageRequest.of(pageNo,pageSize);return userDao.findAll(pageable);}@Overridepublic User getUser(Long id) {try {return userDao.findById(id).get();}catch (NoSuchElementException e){return null;}}
}

6.controller层

@Api(tags = "用户管理")
@RequestMapping("/user")
@RestController
public class UserController {Logger log = LoggerFactory.getLogger(UserController.class);@Autowiredprivate UserService userService;@ApiOperation(value = "添加功能")@PostMapping(path = "/add")public Result add(@RequestBody User user){if(StringUtils.isEmpty(user.getUsername())){return Result.error500("参数错误",null);}log.info(user.toString());userService.save(user);return Result.ok("添加成功",null);}@ApiOperation(value = "删除功能")@DeleteMapping(path = "/delete")public Result delete(@RequestParam("id") String id){if(StringUtils.isEmpty(id)){return Result.error500("参数错误",null);}userService.delete(Long.valueOf(id));return Result.ok("删除成功",null);}@ApiOperation(value = "修改功能")@PutMapping(path = "/update")public Result update(User user){userService.update(user);return Result.ok("修改成功",null);}@ApiOperation(value = "分页查询")@GetMapping(path = "/list")public Result list(@RequestParam(value = "pageNo",defaultValue = "0") Integer pageNo,@RequestParam(value = "pageSize",defaultValue = "10") Integer pageSize){Page<User> list = userService.list(pageNo, pageSize);return Result.ok(null,list);}@ApiOperation(value = "详情")@GetMapping(path = "/details/{id}")public Result details(@PathVariable("id")Long id){User user = userService.getUser(id);if(user==null){return Result.error500("用户不存在",null);}return Result.ok("",user);}
}

7.分页查询测试打印如下
JPA Page类属性如下

{"status": 200,"message": null,"data": {"content": [{"id": 3,"username": "aaaa","createTime": null},{"id": 4,"username": "xxx","createTime": null}],"pageable": {"sort": {"sorted": false,"unsorted": true,"empty": true},"offset": 0,"pageSize": 10,"pageNumber": 0,"unpaged": false,"paged": true},"totalPages": 1,"totalElements": 2,"last": true,"size": 10,"number": 0,"sort": {"sorted": false,"unsorted": true,"empty": true},"numberOfElements": 2,"first": true,"empty": false},"time": "2020-09-15 16:48:24"
}