需要把当前类加到项目里面的文件夹下

import org.springframework.boot.web.servlet.MultipartConfigFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.CorsRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import javax.servlet.MultipartConfigElement;

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**")
                .allowedOrigins("*")
                .allowedMethods("POST", "GET", "PUT", "OPTIONS", "DELETE")
                .maxAge(3600)
                .allowCredentials(true);


    }
    @Bean
    public MultipartConfigElement multipartConfigElement(){
        MultipartConfigFactory factory = new MultipartConfigFactory();
        //文件最大KB,MB
        factory.setMaxFileSize("2MB");
        //设置总上传数据总大小
        factory.setMaxRequestSize("10MB");
        return factory.createMultipartConfig();
    }

}