需求:根据用户id查询用户信息

一.配置

1.mybatis.xml

<configuration>
    <!-- 配置别名 -->
    <typeAliases>
        <!-- 批量扫描别名 -->
        <package name="com.steven.ssm.po"/>
    </typeAliases>
    <mappers>
        <mapper resource="sqlmap/UserMapper.xml"/>
    </mappers>
</configuration>

2.applicationContext-dao.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <!-- 加载db.properties -->
    <context:property-placeholder location="config/mybatis/db.properties" />
    <!-- 1.配置数据源(c3p0数据库连接池)-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <!-- 基础配置 -->
        <property name="jdbcUrl" value="${jdbc.url}"/>
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="user" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    
    <!-- 2.配置sqlSessionFactory对象 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <!-- 加载数据库源 -->
        <property name="dataSource" ref="dataSource" />
        <!-- 加载mybatis的全局配置文件 -->
        <property name="configLocation" value="config/mybatis/mybatis.xml" />
    </bean>
    
    <!-- 3.配置userDaoImpl -->
    <bean id="userDaoImpl" class="com.steven.ssm.dao.UserDaoImpl">
        <property name="sqlSessionFactory" ref="sqlSessionFactory"/>
    </bean>
</beans>

配置数据库源、sqlSessionFactory对象以及UserDaoImpl的bean。

二.映射

<mapper namespace="com.steven.ssm.mapper.UserMapper">
        <select id="findUserById" resultType="User" parameterType="int">
            select * from user where id=#{id}
        </select>
</mapper>

三.接口以及接口实现类

public interface UserDao {
    User findUserById(int id) throws Exception;
}

public class UserDaoImpl extends SqlSessionDaoSupport implements UserDao{

    @Override
    public User findUserById(int id) throws Exception {
        SqlSession sqlSession = this.getSqlSession();
        User user = sqlSession.selectOne("findUserById",1);
        return user;
    }
}

四.po类编写

public class User {
    //属性名要和数据库表的字段对应
    private int id;
    private String username;// 用户姓名
    private String sex;// 性别
    private String birthday;// 生日
    private String address;// 地址
    //get和set方法......
}

五.测试

ApplicationContext applicationContext = new ClassPathXmlApplicationContext("config/spring/applicationContext-dao.xml");
UserDaoImpl userDaoImpl = (UserDaoImpl) applicationContext.getBean("userDaoImpl");
User user = userDaoImpl.findUserById(1);
System.out.println(user);