MyBatis简单配置

1、在Maven的pom.xml中导入Mybatis和MySQL数据库驱动依赖

<dependencies>
    <!--mybatis依赖-->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.5</version>
        </dependency>

    <!--mysql驱动-->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
    </dependency>
</dependencies>

2、在Maven项目中的resources下创建mybatis-config.xml配置文件

<?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>
    <!--扫描实体类包,则AdminMapper.xml的resultType中可直接填写实体类名(不区分大小写)-->
    <typeAliases>
        <package name="com.tyh.pojo"/>
    </typeAliases>

    <!--核心配置信息-->
    <environments default="development">
        <!--数据库相关配置-->
        <environment id="development">
            <!--事务控制类型-->
            <transactionManager type="JDBC"/>
                <!--数据库连接参数-->
                <dataSource type="POOLED">
                    <!--数据库连接信息-->
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/testjavaweb?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                    <property name="username" value="root"/>
                    <property name="password" value="123456"/>
                </dataSource>
        </environment>
    </environments>

    <mappers>
        <!--加载sql映射文件-->
        <!--<mapper resource="com/tyh/mapper/AdminMapper.xml"/>-->
        <!--代理简化方式  扫描包-->
        <package name="com.tyh.mapper"/>
    </mappers>
</configuration>

3、在com.tyh.utils下创建MybatisUtils.java工具类

package com.tyh.utils;

import org.apache.ibatis.io.Resources;
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 {
            String mybatisConfig = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(mybatisConfig);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}

4、在com.tyh.pojo中创建Admin.java实体类

5、在Maven:main.java.com.tyh.mapper中创建AdminMapper.java接口，即dao接口

package com.tyh.mapper;

import com.tyh.pojo.Admin;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface AdminMapper {
    //查询所有用户
    List<Admin> selectAll();
}

6、在Maven:main/resources/com/tyh/mapper中创建AdminMapper.xml配置文件，即daoImpl实现类

<?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.tyh.mapper.AdminMapper">

    <select id="selectAll" resultType="com.tyh.pojo.Admin">
        select * from admin;
    </select>

</mapper>

7、测试：在Maven中test.java.com.tyh.test下创建TestAdminMybatis.java测试类

先导入Test依赖：

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.13.2</version>
    <scope>test</scope>
</dependency>

再编写测试代码： 

package com.tyh.test;

import com.tyh.mapper.AdminMapper;
import com.tyh.pojo.Admin;
import com.tyh.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;

import java.io.IOException;
import java.util.List;

public class TestAdminMyBatis {
    @Test
    public void TestSelectAll() throws IOException {
        //1、获取SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = MybatisUtils.getSqlSessionFactory();

        //2、获取SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //3、获取Mapper接口的代理对象
        AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);

        //4、执行方法
        List<Admin> list = adminMapper.selectAll();
        for (Admin a : list){
            System.out.println(a);
        }

        //5、释放资源
        sqlSession.close();
    }
}