HttpServletRequest - Get query string parameters no form data

Question

In HttpServletRequest  getParameterMap returns a Map of all query string parameters and post data parameters   Is there a way to get a Map of ONLY query string parameters  I m trying to avoid using getQueryString and parsing out the values

User · Answer

As the other answers state there is no way getting query string parameters using servlet api.

So, I think the best way to get query parameters is parsing the query string yourself. ( It is more complicated iterating over parameters and checking if query string contains the parameter)

I wrote below code to get query string parameters. Using apache StringUtils and ArrayUtils which supports CSV separated query param values as well.

Example: username=james&username=smith&password=pwd1,pwd2 will return

password : [pwd1, pwd2] (length = 2)

username : [james, smith] (length = 2)

public static Map<String, String[]> getQueryParameters(HttpServletRequest request) throws UnsupportedEncodingException {
    Map<String, String[]> queryParameters = new HashMap<>();
    String queryString = request.getQueryString();
    if (StringUtils.isNotEmpty(queryString)) {
        queryString = URLDecoder.decode(queryString, StandardCharsets.UTF_8.toString());
        String[] parameters = queryString.split("&");
        for (String parameter : parameters) {
            String[] keyValuePair = parameter.split("=");
            String[] values = queryParameters.get(keyValuePair[0]);
            //length is one if no value is available.
            values = keyValuePair.length == 1 ? ArrayUtils.add(values, "") :
                    ArrayUtils.addAll(values, keyValuePair[1].split(",")); //handles CSV separated query param values.
            queryParameters.put(keyValuePair[0], values);
        }
    }
    return queryParameters;
}

User · Answer

I am afraid there is no way to get the query string parameters parsed separately from the post parameters  BTW the fact that such API absent may mean that probably you should check your design  Why are you using query string when sending POST  If you really want to send more data into URL use REST-like convention  e g   instead of sending   http   mycompany com myapp myservlet first 11 amp second 22  say   http   mycompany com myapp myservlet 11 22

User · Answer

The servlet API lacks this feature because it was created in a time when many believed that the query string and the message body was just two different ways of sending parameters  not realizing that the purposes of the parameters are fundamentally different    The query string parameters  foo bar are a part of the URL because they are involved in identifying a resource  which could be a collection of many resources   like  all persons aged 42    GET  persons age 42   The message body parameters in POST or PUT are there to express a modification to the target resource s   Fx setting a value to the attribute  hair    PUT  persons age 42  hair grey  So it is definitely RESTful to use both query parameters and body parameters at the same time  separated so that you can use them for different purposes  The feature is definitely missing in the Java servlet API

User · Answer

Contrary to what cularis said there can be both in the parameter map   The best way I see is to proxy the parameterMap and for each parameter retrieval check if queryString contains   amp   lt parameterName gt      Note that parameterName needs to be URL encoded before this check can be made  as Qerub pointed out   That saves you the parsing and still gives you only URL parameters

User · Answer

Java 8  return Collections list httpServletRequest getParameterNames                       stream                      collect Collectors toMap parameterName - gt  parameterName  httpServletRequest  getParameterValues

User · Answer

You can use request getQueryString   if the query string is like  username james amp password pwd   To get name you can do this  request getParameter  username

[java] HttpServletRequest - Get query string parameters, no form data

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