mybatis-plus中的select（mybatis-plus中的selectmap）

前言：

我在开始用Mybatis-Plus来对数据库进行增删改查时，将里面的函数试了个遍，接下来我就将使用selectByMap函数的简单测试实例写出来，方便没有使用过的朋友们快速上手

正文：

首先我们要使用这个selectByMap函数，需要在我们的Mapper中继承mybatis-plus包中相应的接口

1 2 3 4 5 6 package com.example.library.Mapper; import com.example.library.entity.bookBorrowing; import com.baomidou.mybatisplus.core.mapper.BaseMapper; public interface borrowMapper extends BaseMapper<bookBorrowing>{ }

其中BaseMapper中接口就有该函数：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 // IntelliJ API Decompiler stub source generated from a class file // Implementation of methods is not available package com.baomidou.mybatisplus.core.mapper; public interface BaseMapper <T> extends com.baomidou.mybatisplus.core.mapper.Mapper<T> { int insert(T entity); int deleteById(java.io.Serializable id); int deleteByMap(@org.apache.ibatis.annotations.Param("cm") java.util.Map<java.lang.String,java.lang.Object> columnMap); int delete(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); int deleteBatchIds(@org.apache.ibatis.annotations.Param("coll") java.util.Collection<? extends java.io.Serializable> idList); int updateById(@org.apache.ibatis.annotations.Param("et") T entity); int update(@org.apache.ibatis.annotations.Param("et") T entity, @org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> updateWrapper); T selectById(java.io.Serializable id); java.util.List<T> selectBatchIds(@org.apache.ibatis.annotations.Param("coll") java.util.Collection<? extends java.io.Serializable> idList); java.util.List<T> selectByMap(@org.apache.ibatis.annotations.Param("cm") java.util.Map<java.lang.String,java.lang.Object> columnMap); T selectOne(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); java.lang.Integer selectCount(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); java.util.List<T> selectList(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); java.util.List<java.util.Map<java.lang.String,java.lang.Object>> selectMaps(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); java.util.List<java.lang.Object> selectObjs(@org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); <E extends com.baomidou.mybatisplus.core.metadata.IPage<T>> E selectPage(E page, @org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); <E extends com.baomidou.mybatisplus.core.metadata.IPage<java.util.Map<java.lang.String,java.lang.Object>>> E selectMapsPage(E page, @org.apache.ibatis.annotations.Param("ew") com.baomidou.mybatisplus.core.conditions.Wrapper<T> queryWrapper); }

其中的selectByMap调用的就是其中的函数。

接下来就是调用的方法：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 package com.example.library; import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper; import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper; import org.junit.jupiter.api.Test; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import com.example.library.Mapper.*; import com.example.library.entity.*; import org.mybatis.spring.annotation.MapperScan; import java.util.Arrays; import java.util.HashMap; import java.util.List; import java.util.Map; @MapperScan("com/example/library/Mapper") @SpringBootTest class LibraryApplicationTests { @Autowired private borrowMapper borrowMapper; @Test public void mapSelect(){ Map<String,Object> map = new HashMap<String, Object>(); map.put("student_code","123456"); List<bookBorrowing> stu = borrowMapper.selectByMap(map); for(bookBorrowing s:stu){ System.out.println(s); } } }