在Spring Boot中配置上傳文件大小限制有兩種方法：

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來限制上傳文件的大小：

# 設置最大文件上傳大小
spring.servlet.multipart.max-file-size=10MB
# 設置最大請求大小
spring.servlet.multipart.max-request-size=10MB

2. 使用Java配置類配置： 創建一個配置類，繼承WebMvcConfigurerAdapter，并重寫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);
    }

}

以上兩種方法可以實現對上傳文件大小的限制。