在Zuul预过滤器中修改请求正文无效

Question

In my app I am using netflix zuul to route a request from a microservice (gateway) to another. The requests are being routed fine but I also want to introduce some parameters in the request body before it is routed to the appropriate microservice. For this I am using Zuul pre filter like this.

public class SimpleFilter extends ZuulFilter {

    private static Logger log = LoggerFactory.getLogger(SimpleFilter.class);

    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 1;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() {

        try {
            RequestContext context = RequestContext.getCurrentContext();

            InputStream in = (InputStream) context.get("requestEntity");
            if (in == null) {
                in = context.getRequest().getInputStream();
            }

            String body = StreamUtils.copyToString(in, Charset.forName("UTF-8"));

            // body = "request body modified via set('requestEntity'): "+ body;
            body = body.toUpperCase();
            context.set("requestEntity", new ByteArrayInputStream(body.getBytes("UTF-8")));

        } catch (IOException e) {
            log.error(e.getMessage(), e);
        }

        return null;
    }

}

For now I am just trying to change the body to upper case but the microservice to which this request is routed doesn't receive the modified body (upper case). Instead it receives the original one. Am I doing something wrong. Any help would be appreciated. Thanks !!

Answer 1

试试这个吧，这可能在您的情况下有效。

requestContext.getCurrentContext().put("requestEntity", new ByteArrayInputStream(body.getBytes("UTF-8")));

Answer 2

Was able to do the following - transform a GET request to a POST request, and add body content to the (proxied) POST request.

    public Object run() throws ZuulException {
        RequestContext context = RequestContext.getCurrentContext();
        context.addZuulRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        String body = String.format("a=%s&b=%s", a, b);

        final byte[] bytes = body.getBytes(StandardCharsets.UTF_8);
        context.setRequest(new HttpServletRequestWrapper(context.getRequest()) {
            @Override
            public ServletInputStream getInputStream() {
                return new ServletInputStreamWrapper(bytes);
            }

            @Override
            public int getContentLength() {
                return bytes.length;
            }

            @Override
            public long getContentLengthLong() {
                return bytes.length;
            }

            @Override
            public String getMethod() {
                return "POST";
            }
        });

        return null;
    }

Answer 3

Turned out this method cannot change the request body within the requestContext. Truly in the requestContext, a new field "requestEntity" is added, however, the request body from context.getRequest().getInputStream() remains the same after this operation.

Answer 4

You can modify the request body, see this answer for an example. You just need to wrap the new request data and make sure you correctly report it's new content length.