springboot 整合 jpa

傷城~ 2022-03-21 04:46 466阅读 0赞

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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70][]

填写简单的信息

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 1][]

选择web,Jpa,mysql

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 2][]

选择存放路径

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 3][]

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/> 
        </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

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 4][]

接下来我还是访问昨天创建的 test 数据库 happiness 表

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 5][]

根据 happiness 编写实体类，先来看一下 项目结构：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 6][]

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][http_127.0.0.1_8080_getHappiness]

![2019013017560388.png][]

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][https_blog.csdn.net_static_coder_article_details_79758085]

最后贴上 源码地址： [https://github.com/taoxiaotao6/springboot\_jpa.git][https_github.com_taoxiaotao6_springboot_jpa.git]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 2]: /images/20220321/ba30c324f6d8462d8fc40ad5a119febc.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 5]: /images/20220321/d9eb97c3c9864869bbd12fe96773a1ce.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpdXlpbmcxODAyMDI4OTE1_size_16_color_FFFFFF_t_70 6]: /images/20220321/4bd7f27b802c493f9b63da519c2a8224.png
[http_127.0.0.1_8080_getHappiness]: http://127.0.0.1:8080/getHappiness
[2019013017560388.png]: /images/20220321/30e5224a2d0a4051b193316874f8d6f4.png
[https_blog.csdn.net_static_coder_article_details_79758085]: https://blog.csdn.net/static_coder/article/details/79758085
[https_github.com_taoxiaotao6_springboot_jpa.git]: https://github.com/taoxiaotao6/springboot_jpa.git