spring boot学习第五篇:spring boot与JPA结合

1、准备表，创建表语句如下

CREATE TABLE `girl` (`id` int(11) NOT NULL AUTO_INCREMENT,`cup_Size` varchar(100) COLLATE utf8mb4_bin DEFAULT NULL,`age` int(11) DEFAULT NULL,PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

2、pom.xml文件，内容如下

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.6.4</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.hmblogs</groupId><artifactId>backend</artifactId><version>0.0.1-SNAPSHOT</version><name>backend</name><description>backend</description><properties><java.version>8</java.version><druid.version>1.2.8</druid.version></properties><dependencies><!-- druid数据源驱动 --><dependency><groupId>com.alibaba</groupId><artifactId>druid-spring-boot-starter</artifactId><version>${druid.version}</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.28</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

3、GirlController.java控制层代码，如下

package com.hmblogs.backend.controller;import com.hmblogs.backend.dao.GirlRep;
import com.hmblogs.backend.entity.Girl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;import java.util.List;@RestController
public class GirlController {@Autowiredprivate GirlRep girlRep;/*** 查询所有女生列表* @return*/@GetMapping(value = "/girls")public List<Girl> getGirlList(){return girlRep.findAll();}/*** 添加一个女生* @param cupSize* @param age* @return*/@RequestMapping(value = "/girls",method = RequestMethod.POST)public Girl addGirl(@RequestParam("cupSize") String cupSize,@RequestParam("age") Integer age){Girl girl = new Girl();girl.setAge(age);girl.setCupSize(cupSize);return girlRep.save(girl);}}

4、dao层代码如下，

package com.hmblogs.backend.dao;import com.hmblogs.backend.entity.Girl;
import org.springframework.data.jpa.repository.JpaRepository;//其中第二个参数为Id的类型
public interface GirlRep extends JpaRepository<Girl,Integer> {
}

5、entity类代码如下

package com.hmblogs.backend.entity;import lombok.Data;import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;@Entity
@Data
public class Girl {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Integer id;private String cupSize;private Integer age;}

6、启动类代码如下

package com.hmblogs.backend;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class BackendApplication {public static void main(String[] args) {SpringApplication.run(BackendApplication.class, args);}}

7、application.yml代码如下

server:port: 8080servlet.context-path: /backendspring:datasource:druid:db-type: com.alibaba.druid.pool.DruidDataSourcedriverClassName: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://${DB_HOST:localhost}:${DB_PORT:3306}/${DB_NAME:eladmin}?serverTimezone=Asia/Shanghai&characterEncoding=utf8&useSSL=falseusername: ${DB_USER:root}password: ${DB_PWD:123456}

9、启动成功，并且贴出代码结构