Question

Some PHP sites use a page to act as a middle man for handling file downloads.

With a browser this works transparently. There seems to a be a slight pause while the php page processes the request.

However, attempting a download through Java using a URL or HttpURLConnection returns a plain html page. How could I get the file downloads working in the same way?

Edit: Here is an example link:

http://depot.eice.be/index.php?annee_g=jour&cours=poo

Edit: Here is some of the code I’ve been testing:

// This returns an HTML page

private void downloadURL(String theURL) {
    URL url;
    InputStream is = null;
    DataInputStream dis;
    String s;
    StringBuffer sb = new StringBuffer();

    try {
        url = new URL(theURL);

        HttpURLConnection conn = (HttpURLConnection) url.openConnection();

        conn.setRequestMethod("GET");
        conn.connect();

        if (conn.getResponseCode()!=HttpURLConnection.HTTP_OK)
            return;


        InputStream in = conn.getInputStream();

        ByteArrayOutputStream bos = new ByteArrayOutputStream();

        int i;
        while ((i = in.read()) != -1) {
            bos.write(i);
        }

        byte[] b = bos.toByteArray();

        FileOutputStream fos = new FileOutputStream( getNameFromUrl( theURL ) );
        fos.write(b);
        fos.close();
        conn.disconnect();
    } catch (MalformedURLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

---

// This will throw Exceptions if the URL isn't in the expected format

public String getNameFromUrl(String url) {

    int slashIndex = url.lastIndexOf('/');
    int dotIndex = url.lastIndexOf('.');

    System.out.println("url:" + url + "," + slashIndex + "," + dotIndex);

    if (dotIndex == -1) {
        return url.substring(slashIndex + 1);
    } else {
        try {
            return url.substring(slashIndex + 1, url.length());
        } catch (StringIndexOutOfBoundsException e) {
            return "";

        }
    }
}

Answer 1

I think I’ve found a solution using HttpUnit. The source of the framework is available if you wish to see how this is handled.

public void downloadURL(String url) throws IOException {

    WebConversation wc = new WebConversation();
    WebResponse indexResp = wc.getResource(new GetMethodWebRequest(url));
    WebLink[] links = new WebLink[1];
    try {
        links = indexResp.getLinks();
    } catch (SAXException ex) {
        // Log
    }

    for (WebLink link : links) {
        try {
            link.click();
        } catch (SAXException ex) {
            // Log
        }
        WebResponse resp = wc.getCurrentPage();
        String fileName = resp.getURL().getFile();
        fileName = fileName.substring(fileName.lastIndexOf("/") + 1);
        System.out.println("filename:" + fileName);
        File file = new File(fileName);
        BufferedInputStream bis = new BufferedInputStream(
                resp.getInputStream());
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream(file.getName()));
        int i;
        while ((i = bis.read()) != -1) {
            bos.write(i);
        }
        bis.close();
        bos.close();
    }
    System.out.println("Done downloading.");
}