上传文件默认允许大小是1MB，在application.yml中配置上传文件限制大小

  #上传文件大小配置
  spring:
     servlet:
       multipart:
          max-file-size: 20MB       #单文件大小
          max-request-size: 200MB   #整体上传大小
          enabled: false

运行时报错：

Unable to process parts as no multi-part configuration has been provided

根据提示，我们是缺少了multipartResolver配置,可以直接新增一个配置类：

package com.xxx.springbootsource.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.multipart.MultipartResolver;
import org.springframework.web.multipart.commons.CommonsMultipartResolver;

@Configuration
public class UploadConfig {
	@Bean(name="multipartResolver")
	public MultipartResolver multipartResolver(){
		return new CommonsMultipartResolver();
	}
}

添加配置类后，运行试试

若报错：

BeanCreationException: Error creating bean with name 'multipartResolver' defined in class path 

检查pom.xml文件中是否引入了commons-fileupload

<dependency>
	<groupId>commons-fileupload</groupId>
	<artifactId>commons-fileupload</artifactId>
	<version>1.3.1</version>
</dependency>