Httpclient 4, error 302. How to redirect?

Question

I want to access one site that first requires an (tomcat server) authentication and then log in with a POST request and keep that user to see the site\'s pages. I use Httpcl

Answer 1

You have to implement custom redirection handler that will indicate that response to POST is a redirection. This can be done by overriding isRedirectRequested() method as shown below.

DefaultHttpClient client = new DefaultHttpClient();
client.setRedirectHandler(new DefaultRedirectHandler() {                
    @Override
    public boolean isRedirectRequested(HttpResponse response, HttpContext context) {
        boolean isRedirect = super.isRedirectRequested(response, context);
        if (!isRedirect) {
            int responseCode = response.getStatusLine().getStatusCode();
            if (responseCode == 301 || responseCode == 302) {
                return true;
            }
        }
        return isRedirect;
    }
});

In later version of HttpClient, the class name is DefaultRedirectStrategy, but similar solution can be used there.

Answer 2

httpclient.setRedirectHandler(new DefaultRedirectHandler());

See HttpClient Javadoc

Answer 3

In later versions of HttpCLient (4.1+), you can just do this:

DefaultHttpClient client = new DefaultHttpClient()
client.setRedirectStrategy(new LaxRedirectStrategy())

LaxRedirectStrategy will automatically redirect HEAD, GET, and POST requests. For a stricter implementation, use DefaultRedirectStrategy.

Answer 4

Redirects are not handled automatically by HttpClient 4.1 for other methods than GET and PUT.

Answer 5

Extend the DefaultRedirectStrategy class and override the methods.
@Override
    protected URI createLocationURI(String arg0) throws ProtocolException {
        // TODO Auto-generated method stub
        return super.createLocationURI(arg0);
    }

    @Override
    protected boolean isRedirectable(String arg0) {
        // TODO Auto-generated method stub
        return true;
    }

    @Override
    public URI getLocationURI(HttpRequest arg0, HttpResponse arg1,
            HttpContext arg2) throws ProtocolException {
        // TODO Auto-generated method stub
        return super.getLocationURI(arg0, arg1, arg2);
    }

    @Override
    public HttpUriRequest getRedirect(HttpRequest request,
            HttpResponse response, HttpContext context)
            throws ProtocolException {
          URI uri = getLocationURI(request, response, context);
          String method = request.getRequestLine().getMethod();
          if (method.equalsIgnoreCase(HttpHead.METHOD_NAME)) {
              return new HttpHead(uri);
          } else {
              return new HttpPost(uri);
          }

    }

    @Override
    public boolean isRedirected(HttpRequest request, HttpResponse response,
            HttpContext context) throws ProtocolException {
        // TODO Auto-generated method stub
        return super.isRedirected(request, response, context);
    }

in this case isRedirectable method will always return true and getRedirect method will return post request in place of get request.

Answer 6

For HttpClient 4.3.x :

HttpClient httpClient = HttpClientBuilder.create().setRedirectStrategy(new LaxRedirectStrategy()).build();