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());

        }
    }
}