springboot 整合 jpa

昨天学习了springboot 如何 整合 简单的mybatis , 今天来学习一下springboot 如何 整合 jpa

spring data jpa 也是用于简化数据库访问的持久化规范，在企业中也经常用到，有必要简单学习一下，今天我就来打一个最简单的springboot-jpa项目。（其实也是做个记录，方便自己以后查询）

一。新建项目

填写简单的信息

选择web,Jpa,mysql

选择存放路径

然后启动项目，因为有了之前的经验，知道是启动不起来的，因为要配置mysql数据库的一些信息

于是，我们在resources目录下，创建 application.yml 文件

# database
spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/test
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: 11111111

# jpa
jpa:
  hibernate:
    ddl-auto: update
  show-sql: true

启动后发现还是报错

日志中有这句提示：

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

然后我就把application.yml 中的驱动类

driver-class-name: com.mysql.jdbc.Driver

改为： 

driver-class-name: com.mysql.cj.jdbc.Driver

继续重启发现还是报错：java.sql.SQLNonTransientConnectionException: CLIENT_PLUGIN_AUTH is required

我百度后有人说是因为我们数据库驱动版本过高，而我本地的数据库版本比较低导致的，所以我要降低数据库驱动的版本

我在创建项目的时候选择springboot 的版本2.1.2  我将springboot 的版本修改为 2.0.8后，pom文件如下：

<?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 http://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>2.0.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.taoj</groupId>
    <artifactId>springboot_jpa02</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_jpa02</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </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>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </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>
            </plugin>
        </plugins>
    </build>

</project>

然后启动，没有报错，并且可以正常访问

 

接下来我还是访问昨天创建的 test 数据库 happiness 表

 

根据 happiness 编写实体类，先来看一下 项目结构：

新建实体类： Happiness

package com.taoj.entity;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="happiness")
public class Happiness {

    @Id
    @GeneratedValue
    private Integer id;

    private String city;

    private String num;

    public Integer getId() {
        return id;
    }

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

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getNum() {
        return num;
    }

    public void setNum(String num) {
        this.num = num;
    }

    @Override
    public String toString() {
        return "Happiness{" +
                "id=" + id +
                ", city='" + city + '\'' +
                ", num='" + num + '\'' +
                '}';
    }
}

新建一个 UserInfoRepository 接口

package com.taoj.repository;

import com.taoj.entity.Happiness;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserInfoRepository extends JpaRepository<Happiness, Integer> {

    Happiness findHappinessById(Integer id);

}

最后编写controller 

package com.taoj.controller;

import com.taoj.entity.Happiness;
import com.taoj.repository.UserInfoRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class HelloController {

    @Autowired
    private UserInfoRepository userInfoRepository;

    @RequestMapping("/hello")
    @ResponseBody
    public String sayHello(){
        return "hello spring boot jpa";
    }

    @RequestMapping("/getHappiness")
    @ResponseBody
    public String getHappiness(){
        Happiness happiness = userInfoRepository.findHappinessById(1001);
        System.out.println(happiness.toString());
        return happiness.toString();
    }

}

最后访问：

http://127.0.0.1:8080/getHappiness

结果正常

 

以上项目是参照别人的博客本地验证的。感谢一下作者：

https://blog.csdn.net/static_coder/article/details/79758085

 

最后贴上 源码地址： https://github.com/taoxiaotao6/springboot_jpa.git