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 {

    @Autowired
    private 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: 8080
  servlet.context-path: /backend

spring:
  datasource:
    druid:
      db-type: com.alibaba.druid.pool.DruidDataSource
      driverClassName: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://${DB_HOST:localhost}:${DB_PORT:3306}/${DB_NAME:eladmin}?serverTimezone=Asia/Shanghai&characterEncoding=utf8&useSSL=false
      username: ${DB_USER:root}
      password: ${DB_PWD:123456}

9、启动成功，并且贴出代码结构