SpringBoot-快速搭建一套JPA-蒲公英云

文章目录

- 结构
- Maven
- application.yml
- 实体类
- dao
- service
- controller
- 测试

结构

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Maven

<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
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application.yml

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

实体类

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

dao

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

service

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();
    }
}

controller

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());
    }
}

测试

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);
 }
}

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