mybatis_2

<?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">
  <!-- 全局配置文件 -->
<configuration>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8"/>
        <property name="username" value="root"/>
        <property name="password" value="root"/>
      </dataSource>
    </environment>
  </environments>

  <!-- 加载映射文件 -->
  <mappers>
    <mapper resource="EmployeeMapper1.xml"/>
    <mapper resource="EmployeeMapper2.xml"/>
  </mappers>
</configuration>

package demo2;

import entity.Employee;

public interface EmployeeMapper {
public Employee getById(int id);
}

<?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">

<!-- demo2 -->
<mapper namespace="com.demo2.EmployeeMapper">
    <!-- 
            mybatis 支持命名空间设置为 dao 接口 进行绑定   框架会自动对接口进行代理  不需要手动实例化
                    sql 唯一id与接口中的方法进行绑定  这里的接口只需要设定好方法的参数而不需要实例化
     -->
      <select id="getById" resultType="org.entity.Employee">
        select * from employee where id = #{id}
      </select>
</mapper>

package demo2;

import java.io.IOException;
import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import entity.Employee;

public class Demo2 {

    public static void main(String[] args) throws IOException {
        // 1、获取sessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder()
                .build(inputStream);
        // 2、获取 session
        SqlSession session = sqlSessionFactory.openSession();
        // 3、获取接口的是实现类对象 自动代理
        EmployeeMapper mapper = session.getMapper(EmployeeMapper.class);

        Employee employee = mapper.getById(1);
        System.out.println(employee.toString());
        session.close();
    }
}