Using ContentCachingRequestWrapper causes Empty Parameters Map

问题

I have implemented a Filter, in which I want to read the content of request first for some checks and then I would like to go on.

But the problem is, that in the following filter from the filter chain the getParameters() Method from class Request (org.eclipse.jetty.server.Request) is called and not the getParameters() method from class ContentCachingRequestWrapper. So the parametersMap are not filled and is always empty.

Here is how my code looks like:

@Component
@Order(1)
public class EncodingFilter extends GenericFilterBean {

private static final Logger LOG = 
LoggerFactory.getLogger(EncodingFilter.class);

@Override
public void doFilter(ServletRequest request, ServletResponse response, 
FilterChain chain) throws IOException, ServletException {

final HttpServletRequest req = (HttpServletRequest) request;
HttpServletRequest servletRequest = new ContentCachingRequestWrapper(req);

String read = ByteSource.wrap(ByteStreams.toByteArray(servletRequest.getInputStream()))
        .asCharSource(StandardCharsets.UTF_8).read();
// Doing analysis .....
// last step call filter chain
chain.doFilter(servletRequest, response);
}
}

And in Controller:

@PostMapping(
    value = Endpoints.Janus.INIT,
    produces = MediaType.TEXT_HTML_VALUE
)
public ModelAndView controller(
    @RequestParam LinkedCaseInsensitiveMap<String> params,
    HttpServletRequest servletRequest
) {
 ....  
}

In the controller the params Map is always empty. If I don't call servletRequest.getInputStream() in my filter, the params Map is filled.

I am working with Spring Boot 1.5.6 with Jetty as Application Server

回答1:

ContentCachingRequestWrapper doesnt work that way and has some limitations. Only POST request and content type should be application/x-www-form-urlencoded as far as I remember. If this fits for you, here's what you should do:

final HttpServletRequest req = (HttpServletRequest) request;
HttpServletRequest servletRequest = new ContentCachingRequestWrapper(req);
servletRequest.getParameterMap(); // needed for caching!!

String read = ByteSource.wrap(servletRequest.getContentAsByteArray())
    .asCharSource(StandardCharsets.UTF_8).read(); // Please note that we're not touching input stream!!

Hope this helps.

回答2:

Please try the two proposed solutions mentioned below:
1. HttpServletRequestWrapper servletRequest = new ContentCachingRequestWrapper(req);
OR
2. ContentCachingRequestWrapper servletRequest = new ContentCachingRequestWrapper(req);
Instead of HttpServletRequest servletRequest = new ContentCachingRequestWrapper(req);
As you can check here that ContentCachingRequestWrapper class extends HttpServletRequestWrapper which extends ServletRequestWrapper and implements HttpServletRequest.
So here by performing upcasting, you are may be facing this issue. Please check and let me know if this is not the case, then I will debug it further.

来源：https://stackoverflow.com/questions/49250367/using-contentcachingrequestwrapper-causes-empty-parameters-map

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java

Spring

embedded-jetty