CODEWITHSUNDEEP
javaservlets
Prakash
Prakash

Reputation:

How to get the parameter values from HTTP "Referer" header?

I got the url value using request.getHeader("Referer") e.g.:

string rr=request.getHeader("Referer");
<%= rr %>

I got the url as http://www.sun.com/questions?uid=21&value=gg

Now I stored that url in as string, how do I get the value parameter value as uid=21 and value=gg

Upvotes: 0

Views: 23844

Answers (4)

Thomas_
Thomas_

Reputation: 1

I combine two codes and result is below:

StringBuffer url = request.getRequestURL(); 
    if(request.getQueryString()!= null){    
    url.append("?"); 
    url.append(request.getQueryString()); 
    } 
    String url_param = url.toString();          
    String[] params = url_param.split("&");

    String[][] param_key = new String[1320][3];
    String[][] param_val = new String[1320][3];
    String param = "";
    String key_tmp = "";
    String val_tmp = "";
    y = 1;

    for(x=1;x<params.length;x++)
    {
        param = params[x];
        key_tmp = param.substring(0, param.indexOf("="));
        param_key[x][y] = key_tmp;
        y++;
        val_tmp = param.substring(param.indexOf("=") + 1);
        param_val[x][y] = val_tmp;
        y=1;
    }

You get two arrays. One contains key(name), second contains values.

Upvotes: 0

Joe23
Joe23

Reputation: 5782

Below an example how Apache Solr does it (SolrRequestParsers).

  /**
   * Given a standard query string map it into solr params
   */
  public static MultiMapSolrParams parseQueryString(String queryString) 
  {
    Map<String,String[]> map = new HashMap<String, String[]>();
    if( queryString != null && queryString.length() > 0 ) {
      try {
        for( String kv : queryString.split( "&" ) ) {
          int idx = kv.indexOf( '=' );
          if( idx > 0 ) {
            String name = URLDecoder.decode( kv.substring( 0, idx ), "UTF-8");
            String value = URLDecoder.decode( kv.substring( idx+1 ), "UTF-8");
            MultiMapSolrParams.addParam( name, value, map );
          }
          else {
            String name = URLDecoder.decode( kv, "UTF-8" );
            MultiMapSolrParams.addParam( name, "", map );
          }
        }
      }
      catch( UnsupportedEncodingException uex ) {
        throw new SolrException( SolrException.ErrorCode.SERVER_ERROR, uex );
      }
    }
    return new MultiMapSolrParams( map );
  }

Usage:

MultiMapSolrParams params = SolrRequestParsers.parseQueryString( req.getQueryString() );

And an example how Jersey does it (UriComponent):

/**
 * Decode the query component of a URI.
 * 
 * @param q the query component in encoded form.
 * @param decode true of the query parameters of the query component
 *        should be in decoded form.
 * @return the multivalued map of query parameters.
 */
public static MultivaluedMap<String, String> decodeQuery(String q, boolean decode) {
    MultivaluedMap<String, String> queryParameters = new MultivaluedMapImpl();

    if (q == null || q.length() == 0) {
        return queryParameters;
    }

    int s = 0, e = 0;
    do {
        e = q.indexOf('&', s);

        if (e == -1) {
            decodeQueryParam(queryParameters, q.substring(s), decode);
        } else if (e > s) {
            decodeQueryParam(queryParameters, q.substring(s, e), decode);
        }
        s = e + 1;
    } while (s > 0 && s < q.length());

    return queryParameters;
}

private static void decodeQueryParam(MultivaluedMap<String, String> params,
        String param, boolean decode) {
    try {
        int equals = param.indexOf('=');
        if (equals > 0) {
            params.add(
                    URLDecoder.decode(param.substring(0, equals), "UTF-8"),
                    (decode) ? URLDecoder.decode(param.substring(equals + 1), "UTF-8") : param.substring(equals + 1));
        } else if (equals == 0) {
            // no key declared, ignore
        } else if (param.length() > 0) {
            params.add(
                    URLDecoder.decode(param, "UTF-8"),
                    "");
        }
    } catch (UnsupportedEncodingException ex) {
        // This should never occur
        throw new IllegalArgumentException(ex);
    }
}

Upvotes: 0

Brian Agnew
Brian Agnew

Reputation: 272287

You need to:

  1. take the string after the '?'
  2. split that on '&' (you can do this and the above by using the URL object and calling getQuery())
  3. You'll then have strings of the form 'x=y'. Split on the first '='
  4. URLDecode the result parameter values.

This is all a bit messy, unfortunately.

Why the URLDecode step ? Because the URL will be encoded such that '=' and '?' in parameter values won't confuse a parser.

Upvotes: 4

user7094
user7094

Reputation:

This tutorial might help a bit.

What you need to do is parse the URL, then get the 'query' property, then parse it into name/value pairs.

So something like this:

URL url = new URL(referer);
String queryStr = url.getQuery();

String[] params = queryStr.split("&");
for (String param: params) {
    String key = param.substring(0, param.indexOf('=');
    String val = param.substring(param.indexOf('=') + 1);
}

Disclaimer: this has not been tested, and you will need to do more error checking!

Upvotes: 3

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