create database mybatis;
 use mybatis;
 CREATE TABLE users(id INT PRIMARY KEY AUTO_INCREMENT, NAME VARCHAR(), age INT);
 INSERT INTO users(NAME, age) VALUES('孤傲苍狼', );
 INSERT INTO users(NAME, age) VALUES('白虎神皇', );

<?xml version="." encoding="UTF-"?>
 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config .//EN" "http://mybatis.org/dtd/mybatis--config.dtd">
 <configuration>
   <environments default="development">
     <environment id="development">
       <transactionManager type="JDBC" />
       <!-- 配置数据库连接信息 -->
       <dataSource type="POOLED">
         <property name="driver" value="com.mysql.jdbc.Driver" />
         <property name="url" value="jdbc:mysql://localhost:/mybatis" />
         <property name="username" value="root" />
         <property name="password" value="XDP" />
       </dataSource>
     </environment>
   </environments>
   
 </configuration>

package me.gacl.domain;
 
 /**
  * @author gacl
  * users表所对应的实体类
  */
 public class User {
 
   //实体类的属性和表的字段名称一一对应
   private int id;
   private String name;
   private int age;
 
   public int getId() {
     return id;
   }
 
   public void setId(int id) {
     this.id = id;
   }
 
   public String getName() {
     return name;
   }
 
   public void setName(String name) {
     this.name = name;
   }
 
   public int getAge() {
     return age;
   }
 
   public void setAge(int age) {
     this.age = age;
   }
 
   @Override
   public String toString() {
     return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
   }
 }

  <select id="getUser" parameterType="int" 
     resultType="me.gacl.domain.User">
     select * from users where id=#{id}
   </select>
 </mapper>

 <?xml version="." encoding="UTF-"?>
 <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config .//EN" "http://mybatis.org/dtd/mybatis--config.dtd">
 <configuration>
   <environments default="development">
     <environment id="development">
       <transactionManager type="JDBC" />
       <!-- 配置数据库连接信息 -->
       <dataSource type="POOLED">
         <property name="driver" value="com.mysql.jdbc.Driver" />
         <property name="url" value="jdbc:mysql://localhost:/mybatis" />
         <property name="username" value="root" />
         <property name="password" value="XDP" />
       </dataSource>
     </environment>
   </environments>
   
   <mappers>
     <!-- 注册userMapper.xml文件， 
     userMapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/userMapper.xml-->
     <mapper resource="me/gacl/mapping/userMapper.xml"/>
   </mappers>
   
 </configuration>

package me.gacl.test;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import me.gacl.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class Test {
  public static void main(String[] args) throws IOException {
    //mybatis的配置文件
    String resource = "conf.xml";
    //使用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
    InputStream is = Test.class.getClassLoader().getResourceAsStream(resource);
    //构建sqlSession的工厂
    SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
    //使用MyBatis提供的Resources类加载mybatis的配置文件（它也加载关联的映射文件）
    //Reader reader = Resources.getResourceAsReader(resource); 
    //构建sqlSession的工厂
    //SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
    //创建能执行映射文件中sql的sqlSession
    SqlSession session = sessionFactory.openSession();
    /**
     * 映射sql的标识字符串，
     * me.gacl.mapping.userMapper是userMapper.xml文件中mapper标签的namespace属性的值，
     * getUser是select标签的id属性值，通过select标签的id属性值就可以找到要执行的SQL
     */
    String statement = "me.gacl.mapping.userMapper.getUser";//映射sql的标识字符串
    //执行查询返回一个唯一user对象的sql
    User user = session.selectOne(statement, );
    System.out.println(user);
  }
}