Idea2021.3.1 新建第一个Mybatis程序，Mybatis入门

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我是靠谱客的博主热情指甲油，最近开发中收集的这篇文章主要介绍Idea2021.3.1 新建第一个Mybatis程序，Mybatis入门，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1.导入相关依赖：pom.xml导入 Mybatis依赖

 <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.9</version>
        </dependency>


    </dependencies>

2.配置XML 配置文件中包含了对 MyBatis 系统的核心设置

在resources中创建mybatis.xml文件

新建完成之后将以下代码直接复制进去

<?xml version="1.0" encoding="UTF-8" ?>
        <!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/aaa?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF8&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="UserMapper.xml"/>
    </mappers>
</configuration>

注意：修改url，username，password

3.编写util

package com.tao.util;

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 {
            String resource = "mybatis-config.xml";
            InputStream inputStream =  inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //有了sqlSessionFactory，就可以获得sqlsession的实例了
    //sqlSession 完全包含了面向数据库执行sql命令所需的所有方法
    public static SqlSession getSqlsession(){
        return sqlSessionFactory.openSession();
    }

}

4.写实体类

package com.tao.info;

public class userinfo {

    private int id;
    private String name;

    public userinfo() {
    }

    public userinfo(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "userInfo{" +
                "id=" + id +
                ", name='" + name + ''' +
                '}';
    }
}

5.写接口

package com.tao.dao;

import com.tao.info.userinfo;

import java.util.List;

public interface UserDao {

    List<userinfo> getUserList();

}

6.在resources下配置mapper.XML

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

`
<mapper namespace="com.tao.dao.UserDao">
    <select id="getUserList" resultType="com.tao.info.userinfo">
        select * from user
    </select>
</mapper>

namesepace:为接口路径
id：接口中的方法名
resultType:为实体类路径(sql语句返回值)

7.测试

package org.tao.dao;

import com.tao.dao.UserDao;
import com.tao.info.userinfo;
import com.tao.util.mybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {

    @Test
    public void test(){

        //获取SqlSession对象
        SqlSession sqlsession = mybatisUtils.getSqlsession();

        //getMapper
        UserDao mapper = sqlsession.getMapper(UserDao.class);
        List<userinfo> userList = mapper.getUserList();

        for (userinfo userinfo : userList) {
            System.out.println(userinfo);
        }


        //关闭sqlSession
        sqlsession.close();
    }


}

运行之后报错

资源导出问题，找不到
pom.xml中导入如下代码：

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

                <resource>
                    <directory>src/main/resources</directory>
                    <includes>
                        <include>**/*.xml</include>
                        <include>**/*.properties</include>
                    </includes>
                </resource>
            </resources>
        </build>