mybatis(1)

mybatis-config.xml

<?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"/>
      <!-- 配置数据源
              需要配置数据库的四个连接属性
       -->
      <dataSource type="POOLED">
        <property name="driver" value="com.mysql.jdbc.Driver"/>
       <!--数据库url  -->
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
      </dataSource>
    </environment>
  </environments>
  
  
  <!-- 
      mappers标签用来配置 sql 的 mapper配置文件
   -->
  <mappers>
      <!-- mapper引入一个sql语句的配置文件
              resource属性配置你要引入的配置文件的路径
              
       -->
    <mapper resource="com/pojo/UserMapper.xml"/> 
  </mappers>
</configuration>

log4j.properties

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

User.java中的成用变量(同时对应数据库中的字段)

    private Integer id;
    private String lastName;
    private Integer sex;

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    名称空间（一般有两种值）
        一：对应的javaBean的全类名
        二：对应的Mapper接口的全类名
 -->
<mapper namespace="com.pojo.User">    
    <!-- 
        select 标签表示select语句
            id 是给当前这个sql语句配置一个唯一标识
            resultType 执行了select查询语句之后，每行记录对应的javaBean对象全类名
            
        #{id} 在mybatis中点位符 ?
     -->
     
     
  <select id="selectUserById" resultType="com.pojo.User">  
    select id,last_name lastName,sex from t_user where id = #{id}
  </select>
</mapper>

test

@Test
    public void test2() throws Exception
    {
        InputStream is=Resources.getResourceAsStream("mybatis-config.xml");
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(is);
        //获取session对象
        SqlSession ss=sqlSessionFactory.openSession();
        System.out.println(2);
        try {
            User user = ss.selectOne("com.pojo.User.selectUserById", 1);
            System.out.println(user);
        } finally {
            // TODO: handle finally clause
            ss.close();
        }
    }