创建数据库

CREATE TABLE `t_wuzong`(
`id` INT(20) NOT NULL,
`name` VARCHAR(30) DEFAULT NULL,
`pwd` VARCHAR(30) DEFAULT NULL,
PRIMARY KEY (`id`)
)ENGINE=INNODB DEFAULT CHARSET=utf8;

pom.xml文件中导入所需依赖：

   <!--在builder中配置resources，防止资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

 <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.26</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>
    </dependencies>

配置mybatis所需的核心配置文件mybatis-config.xml（resources包下）

<?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.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/t_wuzong?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
            <property name="username" value="root"/>
            <property name="password" value="root"/>
        </dataSource>
    </environment>
</environments>
    <mappers>
        <mapper resource="com/wu/dao/UserMapper.xml"/>
    </mappers>
</configuration>

写一个创建sqlsession的工具类MybatisUtils

package com.wu.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;

//sqlSessionFactoryBuilder--->sqlSessionFactory--->sqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            //使用Mybatis第一获取sqlSessionFactory对象
            String resource="mybatis-config.xml";
            InputStream inputStream= Resources.getResourceAsStream(resource);
            sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
    // SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
}

接下来我们需要创建实体类与数据库表对应，可以使用lombok插件简化我们的代码

首先在pom.xml导入lombok依赖

      <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
        </dependency>

创建实体类

package com.wu.pojo;

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

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private int id;
    private String name;
    private String pwd;
}

通过添加注解自动添加了我们所需方法

然后我们需要去编写接口UserMapper

package com.wu.dao;

import com.wu.pojo.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;
import java.util.Map;

public interface UserMapper {
    //Dao=Mapper查询全部用户
//    @Select("select * from user") 这是注解的方式
    List<User> getUserList();
}

在这个目录下编写映射文件UserMapper.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">
<!--namespace=绑定一个对应的Dao/Mapper接口-->
<mapper namespace="com.wu.dao.UserMapper">
    <!--select查询语句-->
    <select id="getUserList" resultType="com.wu.pojo.User">
      select * from mybatis.user
    </select>
</mapper>

测试一下！

public class UserDaoTest {
    @Test
    public void tset(){

        SqlSession sqlSession= MybatisUtils.getSqlSession();
        try{
            //方式一：getMapper 推荐使用
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            List<User> userList = mapper.getUserList();
            //方式二
            //List<User> userList = sqlSession.selectList("com.wu.dao.UserDao.getUserList");

            for (User user:userList){
                System.out.println(user);
            }
        }catch (Exception e){

        }finally {
            sqlSession.close();
        }
    }