mybatis-210718-02---映射文件_参数处理_单个参数_多个参数

mybatis-210718-02—映射文件_参数处理_单个参数_多个参数

• 单个参数
• 多个参数
• 测试代码
  • EmployeeMapper.java(不使用注解前)
  • EmployeeMapper.java(使用注解后)
  • EmployeeMapper.xml(不使用注解前)
  • EmployeeMapper.xml(使用注解后)
  • MybatisTest.java

---

单个参数

单个参数时：
	mybatis不会做特殊处理
	#{参数名}：取出参数值

---

多个参数

多个参数时：
	mybatis会做特殊处理
	多个参数会被封装成一个map
		key：param1，param2......paramn ； 或者参数的索引也可以（从0开始）
		value：传入的参数值
	#{}就是从map中获取指定的key的值

-------------------------------------------------------------------------------------------------------------------
	异常：
		org.apache.ibatis.binding.BindingException: Parameter 'id' not found. Available parameters are [0, 1, 	param1, param2]
		Caused by: org.apache.ibatis.binding.BindingException: Parameter 'id' not found. Available parameters are [0, 1, param1, param2]
	操作：
		方法：public Employee getEmpByIdAndLastName(Integer id,String lastName);
		取值：#{id},#{lastName}
		
	解决操作：
		方法：public Employee getEmpByIdAndLastName(Integer id,String lastName);
		取值01：#{param1},#{param2}
		取值02：#{0},#{1}
		
	<select id="getEmpByIdAndLastName" resultType="com.bgy.mybatis.bean.Employee">
        select 	
            id,last_name,gender,email
        from 
            tbl_employee
        where
            id=#{param1} and last_name=#{param2}
  	</select>

-------------------------------------------------------------------------------------------------------------------

命名参数：
	明确封装参数值map的key：@Param("id")
	多个参数会被封装成一个map，
		key：使用@Param注解指定的值
		value：参数值
	#{指定的key} 取出对应的参数值

---

测试代码

EmployeeMapper.java(不使用注解前)

package com.bgy.mybatis.dao;
import com.bgy.mybatis.bean.Employee;
public interface EmployeeMapper {
	
    // 单个参数
	public Employee getEmpById(Integer id);
	
    // 多个参数
	public Employee getEmpByIdAndLastName(Integer id,String lastName);
}

---

EmployeeMapper.java(使用注解后)

package com.bgy.mybatis.dao;

import org.apache.ibatis.annotations.Param;

import com.bgy.mybatis.bean.Employee;

public interface EmployeeMapper {
	
	public Employee getEmpById(Integer id);
	
	public Employee getEmpByIdAndLastName(@Param("id")Integer id,@Param("lastName")String lastName);
}

---

EmployeeMapper.xml(不使用注解前)

<?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="com.bgy.mybatis.dao.EmployeeMapper">

  <!-- 
		参数处理，单个参数处理
		where id = #{id}	中 #{参数} 可以为任意值
  -->
  <select id="getEmpById" resultType="com.bgy.mybatis.bean.Employee">
    select 
    	id,last_name,gender,email
    from
    	tbl_employee 
    where 
    	id = #{idabc}
  </select>
  
  <!-- 
		参数处理，多个参数处理	
  -->
  <select id="getEmpByIdAndLastName" resultType="com.bgy.mybatis.bean.Employee">
  	select 	
  		id,last_name,gender,email
  	from 
  		tbl_employee
  	where
  		id=#{param1} and last_name=#{param2}
  </select>
</mapper>

---

EmployeeMapper.xml(使用注解后)

<?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="com.bgy.mybatis.dao.EmployeeMapper">

  <!-- 
		参数处理，单个参数处理
		where id = #{id}	中 #{参数} 可以为任意值
  -->
  <select id="getEmpById" resultType="com.bgy.mybatis.bean.Employee">
    select 
    	id,last_name,gender,email
    from
    	tbl_employee 
    where 
    	id = #{idabc}
  </select>
  
  <!-- 
		参数处理，多个参数处理	
  -->
  <select id="getEmpByIdAndLastName" resultType="com.bgy.mybatis.bean.Employee">
  	select 	
  		id,last_name,gender,email
  	from 
  		tbl_employee
  	where
  		id=#{id} and last_name=#{lastName}
  </select>
</mapper>

---

MybatisTest.java

package com.bgy.mybatis.test;

import static org.junit.jupiter.api.Assertions.*;

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 org.junit.jupiter.api.Test;

import com.bgy.mybatis.bean.Employee;
import com.bgy.mybatis.dao.EmployeeMapper;
import com.bgy.mybatis.dao.EmployeeMapperAnnotation;

class MybatisTest {
	
	public SqlSessionFactory getSqlSessionFactory() throws IOException {
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		return new SqlSessionFactoryBuilder().build(inputStream);
	}

	/**
	 * 测试接口式映射
	 * @throws IOException
	 */
	@Test
	public void test01() throws IOException {
		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
		
		SqlSession openSession = sqlSessionFactory.openSession();
		
		try {
			EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
			Employee employee = mapper.getEmpById(1);
			
			System.out.println("test01");
			System.out.println(employee);
		} finally {
			openSession.close();
		}
	}
	
	/**
	 * 测试注解式映射
	 * @throws IOException
	 */
	@Test
	public void test02() throws IOException{
		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
		
		SqlSession openSession = sqlSessionFactory.openSession();
		
		try {
			EmployeeMapperAnnotation mapper = openSession.getMapper(EmployeeMapperAnnotation.class);
			Employee employee = mapper.getEmpById(1);
			
			System.out.println("test02");
			System.out.println(employee);
		} finally {
			openSession.close();
		}
	}
	
	/**
	 * 测试单个参数，多个参数的不同
	 * @throws IOException
	 */
	@Test
	public void test03() throws IOException{
		SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();
		
		SqlSession sqlSession = sqlSessionFactory.openSession();
		
		try {
			EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
			
			// 测试单个参数
//			Employee employee = mapper.getEmpById(1);
//			System.out.println("测试单个参数");
//			System.out.println(employee);
			
			// 测试多个参数
			Employee employee = mapper.getEmpByIdAndLastName(1, "zhangsan");
			System.out.println("测试多个参数");
			System.out.println(employee);
			
		} finally {
			sqlSession.close();
		}
	}
}