MyBatis 简单入门

添加maven 依赖

    <dependencies>

        <dependency>

            <groupId>org.mybatis</groupId>

            <artifactId>mybatis</artifactId>

            <version>3.5.0</version>

        </dependency>

        <dependency>

            <groupId>mysql</groupId>

            <artifactId>mysql-connector-java</artifactId>

            <version>8.0.17</version>

        </dependency>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>4.12</version>

        </dependency>

    </dependencies>

    <build>

        <plugins>

            <plugin>

                <groupId>org.apache.maven.plugins</groupId>

                <artifactId>maven-surefire-plugin</artifactId>

                <version>2.22.1</version>

            </plugin>

        </plugins>

    </build>

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>

    <properties resource="db.properties"/>

    <!--配置enviroments环境-->

    <environments default="mysql">

        <environment id="mysql">

            <!--指定事务管理的类型，这里简单使用Java的JDBC的提交和回滚设置-->

            <transactionManager type="JDBC"/>

            <!--dataSource 指连接源配置，POOLED是JDBC连接对象的数据源连接池的实现-->

            <dataSource type="POOLED">

                <property name="driver" value="${jdbc.driver}"/>

                <property name="url" value="${jdbc.url}"/>

                <property name="username" value="${jdbc.username}"/>

                <property name="password" value="${jdbc.password}"/>

            </dataSource>

        </environment>

    </environments>

    <mappers>

        <mapper resource="mapper/userMapper.xml"/>

    </mappers>

</configuration>

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">

<mapper namespace="cn.qin.mapper.userMapper">

    <select id="selectall" resultType="cn.qin.entity.user">

      select * from user;

    </select>

</mapper>

接口

public interface userMapper {

    public List<user> selectall();

}

测试

public class TestUser {

    private SqlSessionFactory sqlSessionFactory;

    @Test

    public void test() throws IOException {

        InputStream inputStream= Resources.getResourceAsStream("mybatis-config.xml");

        //读取mybatis 配置文件创建sqlsessionFactory

        SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream);

        inputStream.close();

        //获取sqlsession

        SqlSession sqlSession=sqlSessionFactory.openSession();

        //获取对应mapper

        userMapper mapper=sqlSession.getMapper(userMapper.class);

        //执行并返回结果

        List<user> list=mapper.selectall();

        for (user u: list) {

            System.out.println(u.toString());

        }

    }

}