Mybatis创建程序步骤

建立maven父工程

在pom文件中导入依赖

mysql
mybatis
junit等

    <dependencies>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.1.47</version>   //此处要看自己的版本号，不要复制
        </dependency>
        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

建立子模块并配置xml文件

新建子模块，名为mybatis-01

在resources中添加config.xml文件进行数据库等配置

在xml中配置：

<?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核心配置-->
<configuration>
    <!--environments可以配置多个环境，default选择默认环境-->
    <environments default="development">
        <environment id="development">
            <!--事务管理-->
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis？useSSL=true&useUnicode=true&characterEncoding=utf8"/>
                <property name="username" value="guo"/>
                <property name="password" value="guo"/>
            </dataSource>
        </environment>
    </environments>
</configuration>

编辑mybatis工具类

在java文件中添加包，建立dao，utils

mybatisUtils中写入↓

package com.guo.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;

public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            //第一步！
            // /*使用mybatis获取sqlSessionFactory对象*/
            String resource = "mybatis-config.xml";
            /*获取配置文件resource*/
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**第二步！！
     * 从sqlSessionFactory中获取sqlsession
     * 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();
    }
}

编写实体类代码

新建pojo包

生成get set方法，及带参构造函数

package com.guo.pojo;

/*实体类*/

public class User {
    private int id;
    private String name;
    private String pwd;

    /**默认构造函数*/
    public User(){

    }

    /**alt+ins添加带参构造函数*/
    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    /**alt+ins自动获取get set方法*/
    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;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

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

dao接口，接口实现类

package com.guo.dao;

import com.guo.pojo.User;

import java.util.List;

public interface UserDao {
    List<User> getUserList();
}

mapper

<?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">
<!--接口实现类由原来的userdaoimpl转变为一个mapper配置文件-->
<mapper namespace="com.guo.dao.UserDao">
    <select id="getUserList" resultType="com.guo.pojo.User">
        select * from user
    </select>
</mapper>

测试

package com.guo.dao;

import com.kuang.pojo.User;
import com.kuang.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List<User> userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }
        sqlSession.close();
    }
}

问题总结

1、mapper注册问题
2、maven资源过滤配置
3、mysql版本时区问题