Error reading xml from doPost HttpServletRequest

Question

I am trying to read the XML file being posted using http doPost method. While parsing using SAXParser it throws an Exception:

Content is not allowed in prolog.

The doPost code is:

protected void doPost(HttpServletRequest request, HttpServletResponse response)
{    
    ServletInputStream httpIn = request.getInputStream();        
    byte[] httpInData = new byte[request.getContentLength()];
    StringBuffer readBuffer = new StringBuffer();
    int retVal = -1;
    while ((retVal = httpIn.read(httpInData)) != -1)
    {
        for (int i=0; i<retVal; i++)
        {
            readBuffer.append(Character.toString((char)httpInData[i]));
        }                   
    }

    System.out.println("XML Received" + readBuffer);
    try 
    {
        SAXParser parser = SAXParserFactory.newInstance().newSAXParser();
        ByteArrayInputStream inputStream = new ByteArrayInputStream(
            readBuffer.toString().getBytes("UTF-8"));
        final XmlParser xmlParser = new XmlParser();
        parser.parse(inputStream, xmlParser);               
    }
    catch (Exception e)
    {
        System.out.println("Exception parsing the xml request" + e);
    }
}

This is the JUnit I am testing with:

public static void main(String args[])
{    
    StringBuffer buffer = new StringBuffer();   
    buffer.append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
    buffer.append("<person>");
    buffer.append("<name>abc</name>");
    buffer.append("<age>25</age>");
    buffer.append("</person>");

    try
    {
        urlParameters = URLEncoder.encode(buffer.toString(), "UTF-8");
    } 
    catch (Exception e1)
    {       
        e1.printStackTrace();
    }

    String targetURL = "http://localhost:8888/TestService";

    URL url;
    HttpURLConnection connection = null;  
    try 
    {
        //Create connection
        url = new URL(targetURL);
        connection = (HttpURLConnection)url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/xml");
        connection.setRequestProperty("Content-Length", "" + 
            Integer.toString(urlParameters.getBytes("UTF-8").length));
        connection.setRequestProperty("Content-Language", "en-US");  
        connection.setUseCaches (false);
        connection.setDoInput(true);
        connection.setDoOutput(true);

        //Send request
        DataOutputStream wr = new DataOutputStream (
            connection.getOutputStream ());
        wr.writeBytes (urlParameters);
        wr.flush ();
        wr.close ();
    }
    catch (Exception e)
    {
        e.printStackTrace();           
    }

The XML output in the servlet that I am getting is something like this:

XML Received %3C%3Fxml+version%3D%221.0%22+encoding%3D%22UTF-8%22%3F%3E%3Cperson%3E%

So this is throwing an exception in SAXparser:

What am I doing wrong? Am I sending the XML in wrong way or reading it wrong way?

You're mixing several basic concepts. URL encoding is only necessary if you're sending data in `application/x-www-form-urlencoded` format like so `name1=value1&name2=value2&name3=value3` (like as every HTML `
` does). So if you send XML like `xml=...` then you should indeed URL encode the value, but you should not use `request.getInputStream()`, but just `request.getParameter("xml")` to get it directly as string already. See also http://stackoverflow.com/questions/2793150/how-to-use-java-net-urlconnection-to-fire-and-handle-http-requests — BalusC, Jan 29 '13 at 18:07

score 1 · Accepted Answer · answered Jan 29 '13 at 17:30

You assume

httpInData[i]

is a char, while it is a byte. Your content being UTF-8, that makes a big difference. Use a Reader instead.

Then, you are URLEncoding your XML, which is useless, as it is a POST data. Don't encode it, simply send the data.

replace

urlParameters = URLEncoder.encode(buffer.toString(), "UTF-8");

by

urlParameters = buffer.toString();

Also, the name urlParameter is poorly chosen, as this is a single post body, doesn't go in the url, and isn't really a parameter.

Error reading xml from doPost HttpServletRequest

1 Answers1