项目场景：

为了避免使用jdbc的繁杂，使用mybatis来进行数据库的连接操作，结果真是*了狗了，连接了很长时间才连接上

问题描述：

下面记录一下我的debug过程
1.首先遇到的问题是 communication link fail
搜了一下网上说是因为mysql8.0版本太高，再导入依赖时应该用更高的版本

  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
  </dependency>

但在改了之后发现并没有什么用（后来证明确实如此）
反而 Driver的地址变为了 com.mysql.cj.jdbc.Driver

2.之后遇到了 “1字节的UTF-8序列的字节1无效”得问题
继续搜网上说要把配置文件中的UTF-8 改为 UTF8
改完后果然没问题了
3.编码是没问题了结果又显示数据库连接不上
我真是*了狗了气得我一口老血喷出来
于是我又想到是不是时区的问题因为mysql8.0在连接时需要选择时区为GMT
结果发现不是

我一直用的是下面的配置

jdbc:mysql://localhost:3306/数据库?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8

后来我换为网上给的一个配置

jdbc:mysql://localhost:3306/数据库?useUnicode=true&amp;characterEncoding=utf-8&amp;serverTimezone=GMT

我也不知道为什么突然就行了？？？？？？？？？？？？？？？
但是！会有warning

Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+,

这个warning在连接jdbc时我就遇到过
解决方案
1.在数据库连接的url中添加useSSL=false;

2.url中添加useSSL=true，并且提供服务器的验证证书。

后来想到网上给的useSSL好像是true！原来问题的根源在这里！！！吐了

完整配置：

这里给出我的完整配置哎真麻烦呀

1.导入依赖

  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
  </dependency>

2.编写MyBatis核心配置文件

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url"
                          value="jdbc:mysql://localhost:3306/sql_wangpan?useUnicode=true&amp;characterEncoding=utf-8&amp;serverTimezone=GMT&amp;useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>

3.编写MyBatis工具类

package com.run.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

//sqlSessionFactory----> sqlSession
public class MybatisUtils {
    
    
    private static SqlSessionFactory sqlSessionFactory;

    static {
    
    
        try {
    
    

            //获取Mybatis获取sqlSession对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
    
    
            e.printStackTrace();
        }
    }

    //获取SqlSession连接
    public static SqlSession getSqlSession(){
    
    
        return sqlSessionFactory.openSession();
    }

}

4.创建实体类

package com.run.pojo;


import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class commonuser {
    
    
    private int ID;
    private String username;
    private String password;
    private String phonenumber;
    private String email;
}

5.编写Mapper接口类

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.run.dao.commonuserDao">
<select id="getCommonUserList" resultType="com.run.pojo.commonuser">
    select * from commonuser
</select>
</mapper>

6.编写Mapper.xml配置文件

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.run.dao.commonuserDao">
<select id="getCommonUserList" resultType="com.run.pojo.commonuser">
    select * from commonuser
</select>
</mapper>

7.编写测试类

package com.run.dao;

import com.run.pojo.commonuser;
import com.run.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class commonuserDaoTest {
    
    


    @Test
    public void test(){
    
    
        //第一步：获得sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //方式一：执行SQL
        commonuserDao commonuserDao = sqlSession.getMapper(commonuserDao.class);
        List<commonuser> commonUserList = commonuserDao.getCommonUserList();

        for (commonuser commonuser : commonUserList) {
    
    
            System.out.println(commonuser);
        }

        //关闭SqlSession
        sqlSession.close();
    }
}

可能出现问题说明：Maven静态资源过滤问题


<resources>
    <resource>
        <directory>src/main/java</directory>
        <includes>
            <include>**/*.properties</include>
            <include>**/*.xml</include>
        </includes>
        <filtering>false</filtering>
    </resource>
    <resource>
        <directory>src/main/resources</directory>
        <includes>
            <include>**/*.properties</include>
            <include>**/*.xml</include>
        </includes>
        <filtering>false</filtering>
    </resource>
</resources>

mybatis连接mysql8.0

项目场景：

问题描述：

完整配置：

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