用Idea自动生成Maven工程：
1、引入的依赖：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.0.RELEASE</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.springboot</groupId><artifactId>springbootfileuploat</artifactId><version>0.0.1-SNAPSHOT</version><name>springbootfileuploat</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope><exclusions><exclusion><groupId>org.junit.vintage</groupId><artifactId>junit-vintage-engine</artifactId></exclusion></exclusions></dependency><dependency><groupId>org.jetbrains</groupId><artifactId>annotations</artifactId><version>0.0.1-SNAPSHOT</version><scope>compile</scope></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>

2、配置application.properties

#配置单个上传文件的大小限制
spring.servlet.multipart.max-file-size=2MB
#配置一次请求上传文件的总容量的限制
spring.servlet.multipart.max-request-size=20MB

3、逻辑代码;

package com.springboot.springbootfileuploat.controller;import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;import java.io.File;/*** 文件上传*/@RestController
public class filecontrolller {@PostMapping("/upload")public String fileUploat(MultipartFile file) throws Exception{System.out.println(file.getOriginalFilename());file.transferTo(new File("D:/"+file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."))));return "ok";}}

运行成功