访问 Spring Filter/HandlerInterceptor 多部分和参数（表单字段）

Question

我正在编写一个过滤器（也尝试了一个 HandlerInterceptor），并且需要访问 MultiPart 消息的各个部分 - 包括参数（表单字段）和文件。下面的示例代码只给我标头和一般请求信息，为任何正文/内容请求返回 null，例如getParameter 或 getPart。

public class SampleFilter implements Filter {

    @Override
    public void doFilter (ServletRequest req, ServletResponse resp, FilterChain filterchain) throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;
        HttpServletResponse response = (HttpServletResponse) resp;

        log.info(request.getContentType());  //Works OK
        log.info(request.getHeader("X-Some-Header"));  //Works OK
        log.info(String.valueOf(request.getContentLength()));  //Works OK
        log.info(request.getParameter("some-form-field"));  //Does NOT work

        for (Part p : request.getParts())  //Does NOT work
        {
            log.info("Part:" + p.getName()); 
        }
}

我已经为此创建了一个 HandlerInterceptor 版本，因为我相信这会在 DespatcherServlet 处理了多部分结构之后在管道中稍后发生。这使我能够从请求中获取表单字段/“参数”，但文件部分仍然没有运气。

public class SampleHandler extends HandlerInterceptorAdapter {

        @Override
        public boolean preHandle (HttpServletRequest request, HttpServletResponse resp, Object handler) throws Exception {

            log.info(request.getContentType());
            log.info(request.getHeader("X-sample-header"));
            log.info(String.valueOf(request.getContentLength()));

            for (String msg : request.getParameterValues("sample-field"))
            {
                log.info(msg);
            }

            log.info(String.valueOf(request.getParts().size()));  // Shows 0

            for (Part p : request.getParts())
            {
                log.info("Part:" + p.getName());
            }

            return true;

到目前为止，我发现的大多数示例都是关于普通控制器中的多部分（见下文，我已经有了这个） - 我专门寻找 Filter 或 HandlerInterceptor 或类似的预控制器钩子。

我有一个现有的 RestController 成功实现了 MultiPart 功能，但不确定如何将这个或类似的方法应用于过滤器：

@RestController
@RequestMapping (value = {"/**"})
@Slf4j
public class SampleController {

    @RequestMapping(value = {"/**"}, method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    @ResponseBody
    public ResponseEntity<String> SampleMultipartController(@RequestHeader Map<String, String> httpheaders,
                                                        @RequestParam("param1") String param1,
                                                        @RequestParam("param2") List<String> param2,
                                                        @RequestParam ("file") List<MultipartFile> files) throws IOException {

//etc...

我定义了一个 Commons multipartResolver：

@Bean(name = "multipartResolver")
    public CommonsMultipartResolver multipartResolver() {
        final int MAX_UPLOAD_SIZE = (100 * 1024 * 1024);
        CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver();
        multipartResolver.setMaxUploadSize(MAX_UPLOAD_SIZE + MAX_UPLOAD_SIZE/5);
        multipartResolver.setMaxUploadSizePerFile(MAX_UPLOAD_SIZE);
        multipartResolver.setMaxInMemorySize(MAX_UPLOAD_SIZE/100);
        return multipartResolver;
    }

Answer 1

通过使用HandlerInterceptor 解决了问题（因为这是 DespatcherServlet 后，它似乎已应用 Multipart Resolver 而不是使用过滤器），和通过删除 Commons Multipart 的东西并改用@MultipartConfig 注解。

@MultipartConfig
public class SampleHandler extends HandlerInterceptorAdapter {

    @Override
    public boolean preHandle (HttpServletRequest request, HttpServletResponse resp, Object handler) throws Exception {

可以访问零件/表格数据：

request.getParameter("some-form-field"))

如果有多个：

for (String val : request.getParameterValues("some-form-field"))...etc

对于文件：

MultipartHttpServletRequest req = (MultipartHttpServletRequest) request;
req.getFile("some-file"))...etc...

如果有多个：

MultipartHttpServletRequest req = (MultipartHttpServletRequest) request;
for (MultipartFile file : req.getFiles("some-file"))...etc...

也许有更优雅的方法，但这很有效。

Answer 2

我会在doFilter 中做这样的事情：

@Override
public void doFilter (ServletRequest req, ServletResponse resp, FilterChain filterchain) throws IOException, ServletException {

    HttpServletRequest request = (HttpServletRequest) req;
    HttpServletResponse response = (HttpServletResponse) resp;

    URI uri = new URI(request.getRequestURI());

    Map<String, String> map = Arrays.stream(uri.getRawQuery().split("&"))
            .collect(Collectors.toMap(param -> param.split("=")[0], param -> param.split("=")[0]));

}

然后你的地图中就有你的参数了。