Mybatis学习笔记7 参数处理专题

Mybatis学习笔记6 使用时的一些小技巧_biubiubiu0706的博客-CSDN博客

1.单个简单类型参数

2.Map参数

3.实体类参数

4.多参数

5.@Param注解(命名参数)

6.@Param源码分析

建表

插入点数据

新建模块

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.example</groupId><artifactId>mybatis-06</artifactId><version>1.0-SNAPSHOT</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target></properties><dependencies><!--mybatis依赖--><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.5.10</version></dependency><!--mysql驱动--><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.30</version></dependency><!--junit--><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.13.2</version><scope>test</scope></dependency><!--logback--><dependency><groupId>ch.qos.logback</groupId><artifactId>logback-classic</artifactId><version>1.2.11</version></dependency></dependencies>
</project>

目录结构

1.单个简单类型参数包括:

byte short int long float double char

Byte Short Integer Long Double Char

String

java.util.Date

java.sql.Date

持久层接口

pojo

映射文件

<?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.example.mapper.StuMapper"><!--parameterType属性的作用：告诉mybatis框架，我这个方法的参数类型是什么类型。mybatis框架自身带有类型自动推断机制，所以大部分情况下parameterType属性都是可以省略不写的。SQL语句最终是这样的：select * from t_student where id = ?JDBC代码是一定要给?传值的。怎么传值？ps.setXxx(第几个问号, 传什么值);ps.setLong(1, 1L);ps.setString(1, "zhangsan");ps.setDate(1, new Date());ps.setInt(1, 100);...mybatis底层到底调用setXxx的哪个方法，取决于parameterType属性的值。注意：mybatis框架实际上内置了很多别名。可以参考开发手册。--><select id="selectById" resultType="student" parameterType="java.lang.Long">select * from t_student where id=#{id}</select><select id="selectByName" resultType="student">select * from t_student where name=#{name}</select><select id="selectByBirth" resultType="student">select * from t_student where birth=#{birth}</select><select id="selectBySex" resultType="student">select * from t_student where sex=#{sex}</select>
</mapper>

测试代码

import com.example.mapper.StuMapper;
import com.example.pojo.Student;
import com.example.utils.SqlSessionUtil;
import org.apache.ibatis.session.SqlSession;import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;/*** @author hrui* @date 2023/9/19 1:24*/
public class Test {@org.junit.Testpublic void selectBySex(){SqlSession sqlSession = SqlSessionUtil.openSession();StuMapper mapper = sqlSession.getMapper(StuMapper.class);List<Student> students = mapper.selectBySex('男');students.forEach(student-> System.out.println(student));sqlSession.close();}@org.junit.Testpublic void selectByBirth() throws ParseException {SqlSession sqlSession = SqlSessionUtil.openSession();StuMapper mapper = sqlSession.getMapper(StuMapper.class);//List<Student> students = mapper.selectByBirth(new Date(1978-1900,1,3));SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd");Date parse = simpleDateFormat.parse("1980-10-11");List<Student> students = mapper.selectByBirth(parse);students.forEach(student-> System.out.println(student));sqlSession.close();}@org.junit.Testpublic void selectByName(){SqlSession sqlSession = SqlSessionUtil.openSession();StuMapper mapper = sqlSession.getMapper(StuMapper.class);List<Student> students = mapper.selectByName("张三");students.forEach(student-> System.out.println(student));sqlSession.close();}@org.junit.Testpublic void selectById(){SqlSession sqlSession = SqlSessionUtil.openSession();StuMapper mapper = sqlSession.getMapper(StuMapper.class);List<Student> students = mapper.selectById(1L);students.forEach(student-> System.out.println(student));sqlSession.close();}
}

加上这个或许效率高一点,但是一般不这么麻烦,不需要