在Spring Boot中配置上传文件大小限制有两种方法：

1. application.properties/application.yml文件中配置： 可以在application.properties或application.yml文件中添加如下配置来限制上传文件的大小：

# 设置最大文件上传大小
spring.servlet.multipart.max-file-size=10MB
# 设置最大请求大小
spring.servlet.multipart.max-request-size=10MB

2. 使用Java配置类配置： 创建一个配置类，继承WebMvcConfigurerAdapter，并重写configure方法：

@Configuration
public class WebMvcConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/uploads/**")
                .addResourceLocations("file:/path/to/upload/folder/")
                .setCachePeriod(0);
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        UrlPathHelper urlPathHelper = new UrlPathHelper();
        urlPathHelper.setRemoveSemicolonContent(false);
        configurer.setUrlPathHelper(urlPathHelper);
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        UrlPathHelper urlPathHelper = new UrlPathHelper();
        urlPathHelper.setRemoveSemicolonContent(false);
        configurer.setUrlPathHelper(urlPathHelper);
    }

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/uploads/**")
                .addResourceLocations("file:/path/to/upload/folder/")
                .setCachePeriod(0);
    }

    @Override
    public void configurePathMatch(PathMatchConfigurer configurer) {
        UrlPathHelper urlPathHelper = new UrlPathHelper();
        urlPathHelper.setRemoveSemicolonContent(false);
        configurer.setUrlPathHelper(urlPathHelper);
    }

}

以上两种方法可以实现对上传文件大小的限制。