HTTPClient - Capture a list of all Redirects

问题

Is it possible to capture the full redirect history from a URL using HttpClient?

Say for example we have URL-A which redirects to URL-B which finally sends us to URL-C, is there a way to capture what URLs A, B and C were?

The most obvious option is to manually look for the location tag in the header, and stop when we reach a HTTP 200. This isnt a simple process as we would need to look for circular redirects etc etc...

Now I'm assuming the something along the lines of:

    HttpContext context = new BasicHttpContext(); 
    HttpResponse response = hc.execute(httpget, context);
    //.....
    for(URI u :  ((RedirectLocations)context.getAttribute(DefaultRedirectStrategy.REDIRECT_LOCATIONS)).getAll()){
                System.out.println(u);
    }

will work for this use case?

回答1:

HttpClient supports custom RedirectHandler. You can override the default implementation (DefaultRedirectHandler) to capture all the redirects.

DefaultHttpClient hc = new DefaultHttpClient();

HttpGet httpget = new HttpGet("http://google.com");
HttpContext context = new BasicHttpContext();


hc.setRedirectHandler(new DefaultRedirectHandler() {
    @Override
    public URI getLocationURI(HttpResponse response,
                              HttpContext context) throws ProtocolException {

        //Capture the Location header here
        System.out.println(Arrays.toString(response.getHeaders("Location")));

        return super.getLocationURI(response,context);
    }
});

HttpResponse response = hc.execute(httpget, context);

回答2:

RedirectHandler is deprecated as of 4.1 RedirectStrategy is to be used.

we can override 2 methods isRedirected and getRedirect In your case you can get all redirects by:

final HttpClientContext clientContext = 
        HttpClientContext.adapt(context);
RedirectLocations redirectLocations = (RedirectLocations)
    clientContext.getAttribute(
        HttpClientContext.REDIRECT_LOCATIONS
    );

You can add this code in getRedirect. This can also find this code in getLocationURI method of DefaultRedirectStrategy class.

来源：https://stackoverflow.com/questions/7860188/httpclient-capture-a-list-of-all-redirects

标签

java

apache-httpclient-4.x