Java httpclient登录网站和下载文件 - 会话问题！

Question

I log on to a website using the POST method (httpclient from apache). I let the HttpClient execute the HttpPost, let the connection manager release it and then I want to post a GET message that opens a php-URL file to download a pdf. But all I get is the html file of a "session expired" page (println: File: index_GT_neu.html?fehlermeldung=fehler_sessioncheck )

I was thinking that once i used the instance of HttpClient to log on at the site, I would be able to open another URL that is only available after log on. But appearently I was wrong. Somebody could give me a hint? Thanks in advance!

This is what my main looks like:

    // prepare post method
    HttpPost post = new HttpPost("http://epaper02.niedersachsen.com/epaper/index_GT_neu.html");

    //prepare get method
    HttpGet httpget = new HttpGet("http://epaper01.niedersachsen.com/epaper/getfile.php?pdf=0114_GTB_HP_01.pdf&zeitung=GT&ekZeitung=&Y=11&M=01&D=14&C=0");

    // add parameters to the post method
    List <NameValuePair> parameters = new ArrayList <NameValuePair>();
    parameters.add(new BasicNameValuePair("username", "test"));
    parameters.add(new BasicNameValuePair("passwort", "test")); 
    UrlEncodedFormEntity sendentity = new UrlEncodedFormEntity(parameters, HTTP.UTF_8);
    post.setEntity(sendentity); 

    // create the client and execute the post method
    HttpClient client = new DefaultHttpClient();
    HttpResponse postResponse = client.execute(post);

    //Output the Response from the POST
    System.out.print(convertInputStreamToString(postResponse.getEntity().getContent()));

    //releasing POST 
    EntityUtils.consume(postResponse.getEntity());

    //Execute get
    HttpContext context = new BasicHttpContext();   
    HttpResponse getResponse = client.execute(httpget, context);
    System.out.println("Statusline: " + getResponse.getStatusLine());

    if (getResponse.getStatusLine().getStatusCode() != HttpStatus.SC_OK)
        throw new IOException(getResponse.getStatusLine().toString());
    HttpUriRequest currentReq = (HttpUriRequest) context.getAttribute(ExecutionContext.HTTP_REQUEST);
    String currentUrl = URLDecoder.decode(currentReq.getURI().toString(), "UTF-8");

    int i = currentUrl.lastIndexOf('/');
    String fileName = null;
    if (i < 0) {
        fileName = currentUrl;
    } else {
        fileName = currentUrl.substring(i + 1);
    }
    System.out.println("File: " + fileName);

    //Create file
    OutputStream os = new FileOutputStream( fileName);
    InputStream is = getResponse.getEntity().getContent();
    byte[] buf = new byte[4096];
    int read;
    while ((read = is.read(buf)) != -1) {
        os.write(buf, 0, read);
    }
    os.close();

    client.getConnectionManager().shutdown();

Answer 1

By default, DefaultHttpClient does not have a cookie store. A cookie store is needed in order to store cookies that are populated initially or that are obtained while interacting with the HTTP client. As soon as digging into this topic you will start to think about the scope/sharing of cookies.

You can enable the cookie store with one additional line of code:

DefaultHttpClient client = new DefaultHttpClient();
client.setCookieStore(new BasicCookieStore());

I know, this might be a bit late, still HTH.

Answer 2

I am not familiar with this library but try creating context before calling the post and reuse the same context for the get:

   HttpContext context = new BasicHttpContext();
   // create the client and execute the post method
    HttpClient client = new DefaultHttpClient();
    HttpResponse postResponse = client.execute(post,context);
    ...

    HttpResponse getResponse = client.execute(httpget, context);