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

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

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 amp username smith amp password pwd1 pwd2 will return   password    pwd1  pwd2   length   2   username    james  smith   length   2   public static Map lt String  String   gt  getQueryParameters HttpServletRequest request  throws UnsupportedEncodingException       Map lt String  String   gt  queryParameters   new HashMap lt  gt         String queryString   request getQueryString        if  StringUtils isNotEmpty queryString             queryString   URLDecoder decode queryString  StandardCharsets UTF 8 toString             String   parameters   queryString split   amp             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

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

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

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

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

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