Spring Boot中的文件上载：上载、验证和异常处理

Question

我希望能够将图像上传到服务器，优雅地处理错误和异常，并在表单中向用户显示错误消息，并且理想情况下仅使用现有的准系统Spring Boot和Thymeleaf安装。

使用示例项目gs-上载文件，我可以使用Spring Boot和Thymeleaf将文件上载到服务器。在application.properties中，我设置了spring.http.multipart.max-file-size=1MB和spring.http.multipart.max-estest-size=1MB。但是，当我上传大于1MB的文件时，几个安全和验证问题没有解决。

>

可以上载任何文件。例如，可以上载html文件，并将其托管在服务器上。如何按类型限制文件？在发送请求之前，是否可以在页面中验证它们？如果我有多种上传图像的方法，如何验证所有多部分文件？

用户可以尝试上传大文件，超出Spring和嵌入式Tomcat的默认限制。这会导致org.springframework.web.multipart.MultipartException不是由Spring处理的。如何在上传尝试之前验证文件大小？如果绕过这一点，Spring可以捕获任何文件上传异常，以便显示漂亮的错误消息吗？

默认的Spring错误页面并没有用作所有异常的回退。MultipartException返回一个带有完整stacktrace的Tomcat异常页面（请参见日志1）。

我一直在努力寻找并实施一套解决方案。

修复数字1的一个步骤是修改handleFileUpload，检查内容类型，拒绝未通过此操作的文件：！文件getContentType（）。toLowerCase（）。用（“图像”）开始。这是否始终有效？恶意用户能否绕过此漏洞？我如何检查每个多部分文件，以避免每次都要记住添加这个文件？

@PostMapping("/")
public String handleFileUpload(@RequestParam("file") MultipartFile file, RedirectAttributes redirectAttributes)
        throws MultipartException, IllegalStateException {

    if (file != null && file.getContentType() != null && !file.getContentType().toLowerCase().startsWith("image"))
        throw new MultipartException("not img");

    storageService.store(file);
    redirectAttributes.addFlashAttribute("message",
            "You successfully uploaded " + file.getOriginalFilename() + "!");

    return "redirect:/";
}

添加异常处理程序（ExceptionHandler）不起作用，它根本不会被调用。

@ExceptionHandler({ SizeLimitExceededException.class, MultipartException.class,
        java.lang.IllegalStateException.class })
public ModelAndView handleError(HttpServletRequest req, Exception e) {
    // error("Request: " + req.getRequestURL() + " raised " + ex);

    ModelAndView mav = new ModelAndView();
    mav.addObject("exception", e);
    mav.addObject("url", req.getRequestURL());
    mav.addObject("timestamp", new Date());
    mav.addObject("error", e.getClass());
    mav.addObject("message", e.getMessage());
    mav.addObject("status", HttpStatus.INTERNAL_SERVER_ERROR);
    mav.setViewName("error");
    return mav;
}

3号可以由所有异常的全局异常处理程序来解决。（在这篇文章中详细解释）。但是，我担心它可能会推翻控制器级别的处理程序。

package hello;

import java.util.Date;

import javax.servlet.http.HttpServletRequest;

import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.servlet.ModelAndView;

@ControllerAdvice
class GlobalDefaultExceptionHandler {
    public static final String DEFAULT_ERROR_VIEW = "error";

    @ExceptionHandler(value = Exception.class)
    public ModelAndView defaultErrorHandler(HttpServletRequest req, Exception e) throws Exception {
        // If the exception is annotated with @ResponseStatus rethrow it and let
        // the framework handle it - like the OrderNotFoundException example
        // at the start of this post.
        // AnnotationUtils is a Spring Framework utility class.
        if (AnnotationUtils.findAnnotation(e.getClass(), ResponseStatus.class) != null)
            throw e;

        // Otherwise setup and send the user to a default error-view.
        ModelAndView mav = new ModelAndView();
        mav.addObject("exception", e);
        mav.addObject("url", req.getRequestURL());
        mav.addObject("timestamp", new Date());
        mav.addObject("error", e.getClass());
        mav.addObject("message", e.getMessage());
        mav.addObject("status", HttpStatus.INTERNAL_SERVER_ERROR);
        mav.setViewName(DEFAULT_ERROR_VIEW);
        return mav;
    }
}

我尝试了这个答案，它处理异常但返回错误页面。我想返回原始页面并显示一条漂亮的错误消息。

日志1：

HTTP Status 500 - Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)

type Exception report

message Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)
    org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.parseRequest(StandardMultipartHttpServletRequest.java:111)
    org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.<init>(StandardMultipartHttpServletRequest.java:85)
    org.springframework.web.multipart.support.StandardServletMultipartResolver.resolveMultipart(StandardServletMultipartResolver.java:76)
    org.springframework.web.servlet.DispatcherServlet.checkMultipart(DispatcherServlet.java:1099)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:932)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)
    org.apache.catalina.connector.Request.parseParts(Request.java:2871)
    org.apache.catalina.connector.Request.parseParameters(Request.java:3176)
    org.apache.catalina.connector.Request.getParameter(Request.java:1110)
    org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:381)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
root cause

org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (1292555) exceeds the configured maximum (1048576)
    org.apache.tomcat.util.http.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:811)
    org.apache.tomcat.util.http.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:256)
    org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:280)
    org.apache.catalina.connector.Request.parseParts(Request.java:2801)
    org.apache.catalina.connector.Request.parseParameters(Request.java:3176)
    org.apache.catalina.connector.Request.getParameter(Request.java:1110)
    org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:381)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
note The full stack trace of the root cause is available in the Apache Tomcat/8.5.5 logs.

Apache Tomcat/8.5.5

Answer 1

尝试在应用程序中添加以下内容。设置文件大小限制的属性：

spring.http.multipart.max-file-size=256KB
spring.http.multipart.max-request-size=256KB

来源：https://spring.io/guides/gs/uploading-files/

编辑：自Spring boot 2.0发布以来，属性名称已更改为：

spring.servlet.multipart.max-file-size=128KB
spring.servlet.multipart.max-request-size=128KB

注意Spring之间的差异。http --

Answer 2

回复如何检查文件类型：我已经为此创建了一个自定义验证器。

首先，创建注释：

import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {ImageFileValidator.class})
public @interface ValidImage {
    String message() default "Invalid image file";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};
}

接下来，创建验证器本身：

import org.springframework.web.multipart.MultipartFile;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class ImageFileValidator implements ConstraintValidator<ValidImage, MultipartFile> {

    @Override
    public void initialize(ValidImage constraintAnnotation) {

    }

    @Override
    public boolean isValid(MultipartFile multipartFile, ConstraintValidatorContext context) {

        boolean result = true;

        String contentType = multipartFile.getContentType();
        if (!isSupportedContentType(contentType)) {
            context.disableDefaultConstraintViolation();
            context.buildConstraintViolationWithTemplate(
                    "Only PNG or JPG images are allowed.")
                   .addConstraintViolation();

            result = false;
        }

        return result;
    }

    private boolean isSupportedContentType(String contentType) {
        return contentType.equals("image/png")
                || contentType.equals("image/jpg")
                || contentType.equals("image/jpeg");
    }
}

最后，应用注释：

public class CreateUserParameters {

    @NotNull
    @ValidImage
    private MultipartFile image;
...
}

我已经用Spring Boot 1.5.10（也用Thymeleaf）对此进行了测试

对于最大文件大小，我还希望看到一个与“标准错误机制”一起工作的解决方案，这样您可以像其他字段错误一样显示错误，用户可以更正错误。