public HttpUtils() 
{

}

Constructs an empty HttpUtils object.

 public static StringBuffer getRequestURL(HttpServletRequest req) 
{
	StringBuffer url = new StringBuffer ();
	String scheme = req.getScheme ();
	int port = req.getServerPort ();
	String urlPath = req.getRequestURI();
	//String		servletPath = req.getServletPath ();
	//String		pathInfo = req.getPathInfo ();
	url.append (scheme);		// http, https
	url.append ("://");
	url.append (req.getServerName ());
	if ((scheme.equals ("http") && port != 80)
		|| (scheme.equals ("https") && port != 443)) {
	    url.append (':');
	    url.append (req.getServerPort ());
	}
	//if (servletPath != null)
	//    url.append (servletPath);
	//if (pathInfo != null)
	//    url.append (pathInfo);
	url.append(urlPath);
	return url;
}

Reconstructs the URL the client used to make the request, using information in the HttpServletRequest object. The returned URL contains a protocol, server name, port number, and server path, but it does not include query string parameters.

Because this method returns a StringBuffer, not a string, you can modify the URL easily, for example, to append query parameters.

This method is useful for creating redirect messages and for reporting errors.

 public static Hashtable parsePostData(int len,
    ServletInputStream in) 
{
	// XXX
	// should a length of 0 be an IllegalArgumentException
	if (len < =0)
	    return new Hashtable(); // cheap hack to return an empty hash
	if (in == null) {
	    throw new IllegalArgumentException();
	}
	//
	// Make sure we read the entire POSTed body.
	//
        byte[] postedBytes = new byte [len];
        try {
            int offset = 0;
	    do {
		int inputLen = in.read (postedBytes, offset, len - offset);
		if (inputLen < = 0) {
		    String msg = lStrings.getString("err.io.short_read");
		    throw new IllegalArgumentException (msg);
		}
		offset += inputLen;
	    } while ((len - offset)  > 0);
	} catch (IOException e) {
	    throw new IllegalArgumentException(e.getMessage());
	}
        // XXX we shouldn't assume that the only kind of POST body
        // is FORM data encoded using ASCII or ISO Latin/1 ... or
        // that the body should always be treated as FORM data.
        //
        try {
            String postedBody = new String(postedBytes, 0, len, "8859_1");
            return parseQueryString(postedBody);
        } catch (java.io.UnsupportedEncodingException e) {
            // XXX function should accept an encoding parameter & throw this
            // exception.  Otherwise throw something expected.
            throw new IllegalArgumentException(e.getMessage());
        }
}

Parses data from an HTML form that the client sends to the server using the HTTP POST method and the application/x-www-form-urlencoded MIME type.

The data sent by the POST method contains key-value pairs. A key can appear more than once in the POST data with different values. However, the key appears only once in the hashtable, with its value being an array of strings containing the multiple values sent by the POST method.

The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to spaces, and characters sent in hexadecimal notation (like %xx) are converted to ASCII characters.

 public static Hashtable parseQueryString(String s) 
{
	String valArray[] = null;
	if (s == null) {
	    throw new IllegalArgumentException();
	}
	Hashtable ht = new Hashtable();
	StringBuffer sb = new StringBuffer();
	StringTokenizer st = new StringTokenizer(s, "&");
	while (st.hasMoreTokens()) {
	    String pair = (String)st.nextToken();
	    int pos = pair.indexOf('=');
	    if (pos == -1) {
		// XXX
		// should give more detail about the illegal argument
		throw new IllegalArgumentException();
	    }
	    String key = parseName(pair.substring(0, pos), sb);
	    String val = parseName(pair.substring(pos+1, pair.length()), sb);
	    if (ht.containsKey(key)) {
		String oldVals[] = (String []) ht.get(key);
		valArray = new String[oldVals.length + 1];
		for (int i = 0; i <  oldVals.length; i++) 
		    valArray[i] = oldVals[i];
		valArray[oldVals.length] = val;
	    } else {
		valArray = new String[1];
		valArray[0] = val;
	    }
	    ht.put(key, valArray);
	}
	return ht;
}

Parses a query string passed from the client to the server and builds a HashTable object with key-value pairs. The query string should be in the form of a string packaged by the GET or POST method, that is, it should have key-value pairs in the form key=value, with each pair separated from the next by a & character.

A key can appear more than once in the query string with different values. However, the key appears only once in the hashtable, with its value being an array of strings containing the multiple values sent by the query string.

The keys and values in the hashtable are stored in their decoded form, so any + characters are converted to spaces, and characters sent in hexadecimal notation (like %xx) are converted to ASCII characters.