【SpringBoot】SpringBoot 与JPA整合（十四）

　　本章介绍SpringBoot与JPA整合

整合流程

　　1、新建一个SpringBoot Web项目

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.test</groupId>
    <artifactId>test-springboot-jpa</artifactId>
    <version>1.0-SNAPSHOT</version>


    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.8.RELEASE</version>
    </parent>

    <properties>

        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

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


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

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

        <!-- mysql -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.12</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>


    <!-- SpringBoot打包插件，可以将代码打包成一个可执行的jar包 -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

　　2、引入JPA依赖和JDBC依赖

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

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

　　3、添加配置信息

spring:
  datasource:
    username: admin
    password: 123456
    url: jdbc:mysql://127.0.0.1:3306/test_jpa 6     driver-class-name: com.mysql.jdbc.Driver
  jpa:
    # 底层通过hibernate来实现的
    hibernate:
      # 更新或者创建数据表结构
      ddl-auto: update
      # 控制台显示SQL
    show-sql: true

　　4、编写一个User实体类

package com.test.springboot.entity;

import org.springframework.context.annotation.Configuration;

import javax.persistence.*;

// 使用JAP注解配置映射关系

// 告诉JPA这是一个实体类（和数据表映射的类）
@Entity
// @Table来指定和那个数据表对应；如果省略默认表名就是user;
@Table(name="jpa_user")
public class User {

    // 这是一个主键
    @Id
    @GeneratedValue(strategy =  GenerationType.IDENTITY)
    private Integer id;

    @Column(name = "last_name", length = 50)
    private String lastName;

    // 省略默认列名就是属性名
    @Column
    private String email;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }
}

　　5、编写一个UserRepository类

package com.test.springboot.repository;

import com.test.springboot.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Integer> {

}

　　6、编写一个UserController类

package com.test.springboot.controller;

import com.test.springboot.entity.User;
import com.test.springboot.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

import java.util.Optional;

@RestController
public class UserController {

    @Autowired
    UserRepository userRepository;

    @GetMapping("/user/{id}")
    public User getUser(@PathVariable("id") Integer id) {
        Optional<User> optional = userRepository.findById(id);
        if(optional.isPresent()) {
            return optional.get();
        }
        return null;
    }


    @GetMapping("/user")
    public User insertUser(User user){
        User user1 = userRepository.save(user);
        return user1;
    }
}

　　7、启动SpringBoot Web项目进行测试，查看启动日志，可以看到它自动生成了表

　　　　

　　　浏览器输入地址http://localhost:8080/user?lastName=%E6%9D%8E%E5%9B%9B&email=xx@163.com，新增用户

　　　　

　　　查看用户，输入地址：http://localhost:8080/user/1