我有一个基于Spring MVC构建的应用程序。

我想编写处理请求的简单代理，如下所示：

1. 将相同的HTTP请求发送到某些特定的服务器
2. 从此特定服务器捕获HTTP响应
3. 向请求客户返回相同答案

这是到目前为止我得到的：

public void proxyRequest(HttpServletRequest request, HttpServletResponse response) {
    try {
        HttpUriRequest proxiedRequest = createHttpUriRequest(request);
        HttpResponse proxiedResponse = httpClient.execute(proxiedRequest);
        writeToResponse(proxiedResponse, response);
    } catch (URISyntaxException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void writeToResponse(HttpResponse proxiedResponse, HttpServletResponse response){
    for(Header header : proxiedResponse.getAllHeaders()){
        response.addHeader(header.getName(), header.getValue());
    }
    OutputStream os = null;
    InputStream is = null;
    try {
        is = proxiedResponse.getEntity().getContent();
        os = response.getOutputStream();
        IOUtils.copy(is, os);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally {
        if (os != null) {
            try {
                os.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (is != null) {
            try {
                is.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

private HttpUriRequest createHttpUriRequest(HttpServletRequest request) throws URISyntaxException{
    URI uri = new URI(geoserverConfig.getUrl()+"/wms?"+request.getQueryString());

    RequestBuilder rb = RequestBuilder.create(request.getMethod());
    rb.setUri(uri);

    Enumeration<String> headerNames = request.getHeaderNames();
    while(headerNames.hasMoreElements()){
        String headerName = headerNames.nextElement();
        String headerValue = request.getHeader(headerName);
        rb.addHeader(headerName, headerValue);
    }

    HttpUriRequest proxiedRequest = rb.build();
    return proxiedRequest;
}

可以，但是并非在所有情况下都可以。我已经检查了Chrome的网络监视器，并且使用此代理的某些请求失败。

以下是示例失败的请求响应的标头：

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Disposition: inline; filename=JEDN_EWID.png
Transfer-Encoding: chunked
Date: Thu, 16 Jul 2015 10:31:49 GMT
Content-Type: image/png;charset=UTF-8
Content-Length: 6727

以下是示例成功请求响应的标头：

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Disposition: inline; filename=JEDN_EWID.png
Transfer-Encoding: chunked
Date: Thu, 16 Jul 2015 10:31:49 GMT
Content-Type: image/png;charset=UTF-8
Transfer-Encoding: chunked

更重要的是，Chrome在控制台中引发错误：

GET http://localhost:8080/<rest of url> net::ERR_INVALID_CHUNKED_ENCODING

我正在代理的请求是WMS GetMap请求，我的代理正在将它们转发到隐藏的Geoserver。我注意到失败的请求应该返回透明的512x512
.png图像，这些图像都是空的。成功的图像返回512x512 .png图像，这些图像不仅透明而且还包含一些颜色。