package sun.dao;

 import sun.domain.QueryObj;

 import sun.domain.User;

 import java.util.List;

 public interface UserDao {

     /**

      * 根据已有条件进行查询(if where)

      */

     List<User> findUserByCondition(User user);

     /**

      * 根据集合中的id进行查询(if where foreach)

      */

     List<User> findUserByList(QueryObj qobj);

 }

 <?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="sun.dao.UserDao">

     <resultMap id="userMap" type="sun.domain.User">

         <!--主键字段对应-->

         <id property="user_id" column="id"></id>

         <!--非主键关系对应-->

         <result property="user_name" column="username"></result>

         <result property="user_birthday" column="birthday"></result>

         <result property="user_address" column="address"></result>

         <result property="user_sex" column="sex"></result>

     </resultMap>

     <!--公共sql语句抽取-->

     <sql id="defaultSelect">

         select * from user

     </sql>

     <!--根据条件进行查询-->

     <select id="findUserByCondition" resultMap="userMap" parameterType="user">

         <include refid="defaultSelect"></include>

         <where>

             <if test="user_name!=null">

                 and username=#{user_name}

             </if>

             <if test="user_sex!=null">

                 and sex=#{user_sex}

             </if>

         </where>

     </select>

     <!--根据id列表进行查询-->

     <select id="findUserByList" parameterType="queryobj" resultMap="userMap">

         <include refid="defaultSelect"></include>

         <where>

             <if test="ids!=null and ids.size()>0">

                 <foreach collection="ids" open="id in (" close=")" item="id" separator=",">

                     #{id}

                 </foreach>

             </if>

         </where>

     </select>

 </mapper>

 package sun.test;

 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 org.junit.After;

 import org.junit.Before;

 import org.junit.Test;

 import sun.dao.UserDao;

 import sun.domain.QueryObj;

 import sun.domain.User;

 import java.io.IOException;

 import java.io.InputStream;

 import java.util.ArrayList;

 import java.util.Date;

 import java.util.List;

 public class MybatisTest {

     private InputStream in;

     private SqlSession sqlSession;

     private UserDao userDao;

     @Before

     public void init() throws IOException {

         // 读取配置文件

         in = Resources.getResourceAsStream("SqlMapConfig.xml");

         // 创建SqlSessionFactory

         SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();

         SqlSessionFactory factory = builder.build(in);

         // 使用工厂生产sqlsession对象

         sqlSession = factory.openSession();

         // 使用sqlsession创建UserDao接口代理对象

         userDao = sqlSession.getMapper(UserDao.class);

     }

     @After

     public void destory() throws IOException {

         sqlSession.commit();

         sqlSession.close();

         in.close();

     }

     @Test

     public void conditionTest(){

         User user = new User();

         user.setUser_name("kelvin");

         user.setUser_sex("女");

         List<User> users = userDao.findUserByCondition(user);

         for (User user1 : users) {

             System.out.println(user1);

         }

     }

     @Test

     public void ids(){

         QueryObj queryObj = new QueryObj();

         ArrayList<Integer> ids = new ArrayList<Integer>();

         ids.add(51);

         ids.add(52);

         ids.add(53);

         queryObj.setIds(ids);

         List<User> users = userDao.findUserByList(queryObj);

         for (User user : users) {

             System.out.println(user);

         }

     }

 }