<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.7.6</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>springboot-jpa</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot-jpa</name>
<description>springboot-jpa</description>
<properties>
<java.version>1.8</java.version>
<!-- 文件拷贝时的编码-->
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<!-- 编译时的编码 这里就是你运行项目，会给你的文件进行编码-->
<maven.compiler.encoding>UTF-8</maven.compiler.encoding>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.2.15</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
使用IDEA的可以安装下面的插件这样在使用JPA进行编码的时候非常舒服,各种提示
server:
port: 9878
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver #驱动
url: jdbc:mysql://localhost:3306/demo?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
type: com.alibaba.druid.pool.DruidDataSource
username: root
password: root
jpa:
hibernate:
ddl-auto: update #自动更新 ,每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新
show-sql: true #日志中显示sql语句 ,生产环境不要开启
properties:
hibernate:
enable_lazy_load_no_trans: true #懒加载
注意: 实体类中的字段类型 必须是包装类型,否则会导致查询出现默认值的现象
package com.example.springbootjpa.entity;
import lombok.*;
import org.hibernate.Hibernate;
import javax.persistence.*;
import java.util.Date;
import java.util.Objects;
@Getter
@Setter
@ToString
@RequiredArgsConstructor
@Entity // 标识这是一个实体类，并且使用默认的orm规则，即class名即数据库表中表名，class字段名即表中的字段名
@Table(name = "t_user") //来改变class名与数据库中表名的映射规则
public class UserEntity {
@Id
// GenerationType.IDENTITY使用数据库的自增
// 如果是oracle则需要使用GenerationType.SEQUENCE配合@SequenceGenerator
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", nullable = false)
private Long id;
@Column
private String name;
@Column
private String email;
@Column
private String phone;
@Column
private String password;
@Column
private Integer age;
@Column
private Integer sex;
@Column
private Integer status;
@Temporal(TemporalType.TIMESTAMP)
@Column
private Date creationTime;
@Column
private String site;
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || Hibernate.getClass(this) != Hibernate.getClass(o)) return false;
UserEntity that = (UserEntity) o;
return id != null && Objects.equals(id, that.id);
}
@Override
public int hashCode() {
return getClass().hashCode();
}
}
一般来说,我们都是先设计数据库然后在设计实体类, 如果你是使用的是jpa就可以先设计实体类,而对应的表在启动项目的时候就会自动创建了
public interface UserDao extends JpaRepository<UserEntity, Long> {
}
一般来说继承JpaRepository即可 ,内部包括常规的增删改查
package com.example.springbootjpa.service;
import com.example.springbootjpa.entity.UserEntity;
import java.util.List;
public interface UserService {
//查询全部用户
List<UserEntity> findAll();
}
package com.example.springbootjpa.service.impl;
import com.example.springbootjpa.dao.UserDao;
import com.example.springbootjpa.entity.UserEntity;
import com.example.springbootjpa.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserDao userDao;
@Override
public List<UserEntity> findAll() {
return userDao.findAll();
}
}
package com.example.springbootjpa.controller;
import com.example.springbootjpa.entity.UserEntity;
import com.example.springbootjpa.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private UserService userService;
@RequestMapping("/findAll")
public ResponseEntity<List<UserEntity>> findAll(){
return ResponseEntity.ok(userService.findAll());
}
}
package com.example.springbootjpa;
import com.example.springbootjpa.controller.UserController;
import com.example.springbootjpa.dao.UserDao;
import com.example.springbootjpa.entity.UserEntity;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.ResponseEntity;
import java.util.List;
@SpringBootTest
class SpringbootJpaApplicationTests {
@Autowired
private UserController userController;
@Test
void contextLoads() {
ResponseEntity<List<UserEntity>> all = userController.findAll();
List<UserEntity> body = all.getBody();
System.out.println(body);
}
}
