[MyBatis]-06 parameterType

<!--parameterType 参数类型,用于参数传递的查询-->
	<select id="selUseObject" resultType="User" parameterType="User">
		<!--如果参数是对象可以使用#{属性名来获取}-->
		select * from tb_user where username = #{username} and password = #{password}
	</select>

<?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: 命名空间, 可以随意定义, 一般情况下要写全限定路径
	MyBatis管理SQL语句是通过namespace+id来定位的
 -->
<mapper namespace="com.lin.mapper.UserMapper">
	<!-- 
		select标签用于编写查询语句
			id: sql语句的唯一标识, 类比为方法名
			resultType: 用于设定返回结果的类型(全限定路径)
				如果返回结果是集合, 要写集合泛型的类型
	 -->
	<!-- parameterType, 参数类型, 用于参数的传递 -->
	<select id="selById" resultType="user" parameterType="int">
		<!--
			#{}用于使用参数
				可以用 index, 索引, 从0开始
				也可以用 param+数字, param1, param2
				select * from tb_user where id=#{param1}
		 -->
		select * from tb_user where id = #{0}
	</select>
    <!--parameterType 参数类型,用于参数传递的查询-->
	<select id="selUseObject" resultType="User" parameterType="User">
		<!--如果参数是对象可以使用#{属性名来获取}-->
		select * from tb_user where username = #{username} and password = #{password}
	</select>
	<select id="selUseMap" resultType="User" parameterType="map">
		<!--如果是Map集合,通过#{key}来获取-->
		select * from tb_user where username = #{username} and password = #{password}
	</select>

</mapper>

package com.lin.test;

import com.lin.pojo.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;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class TestMyBatisSelect {
   
    
    
@Test
    public void testSelectById() throws IOException {
        //加载资源
        InputStream is = Resources.getResourceAsStream("mybatis.xml");
        //获取工厂对象
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //获取session 对象
        SqlSession session = factory.openSession();
        /*如果需要传多个参数的话就封装成对象传入*/
        User user = session.selectOne("com.lin.mapper.UserMapper.selById", 2);
        System.out.println(user);

        //关闭资源
        session.close();
    }
    @Test
    public void selectByUserNameAndPassWord() {

        SqlSession session = null;
        try {
            session = new SqlSessionFactoryBuilder()
                    .build(Resources.getResourceAsStream("mybatis.xml"))
                    .openSession();
            User u = new User();
            u.setUsername("zhangsan");
            u.setPassword("123");
            User user = session.selectOne("com.lin.mapper.UserMapper.selUseObject", u);
            System.out.println(user);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    @Test
    public void selectUseMap() {

        SqlSession session = null;
        try {
            session = new SqlSessionFactoryBuilder()
                    .build(Resources.getResourceAsStream("mybatis.xml"))
                    .openSession();
            //出了封装对象还可以使用map集合
            Map<String, String> map = new HashMap<>();
            map.put("username","lisi");
            map.put("password","123");
            User user = session.selectOne("com.lin.mapper.UserMapper.selUseMap", map);
            System.out.println(user);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}