Java框架spring Boot学习笔记（四）：Spring Boot操作MySQL数据库

在pom.xml添加一下代码，添加操作MySQL的依赖jar包。

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

<dependency>
　　<groupId>mysql</groupId>
　　<artifactId>mysql-connector-java</artifactId>
</dependency>

新建dbpeople的一个数据库,用户名root，密码123456

修改application.yml文件

spring:
  profiles:
    active: prod
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/dbpeople
    username: root
    password: 123456
  jpa:
    hibernate:
      ddl-auto: create #update
    show-sql: true

添加一个people类People.java

package com.example.demo;

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

//@Entity对应数据库中的一个表
@Entity
public class People {

    //@Id配合@GeneratedValue，表示id自增长
    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private Integer age;

    //必须要有一个无参的构造函数，不然数据库会报错
    public People() {
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }
}

运行报错：

Thu Nov 16 10:29:29 CST 2017 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

是因为高版本的MySQL连接需要useSSL=true，在application.yml文件中修改MySQL连接的url为

url: jdbc:mysql://localhost:3306/dbpeople?useSSL=true

运行成功刷新数据库发现生成了一个people的表

在application.yml中的ddl-auto设置为create表示每次运行都会删掉以前的表，再建一张新表

jpa:
    hibernate:
        ddl-auto: create 
        show-sql: true        

如果设置成update，如果已经有表不会删掉原来的表，如果没有则新建一张表。

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