Mybatis-Plus中的selectByMap使用实例_Java教程

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

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									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：

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									  // 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：

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									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);

									        }

									    }

									}