Parse a URI String into Name-Value Collection

Question

I ve got the URI like this  https   google com ua oauth authorize client id SS amp response type code amp scope N FULL amp access type offline amp redirect uri http   localhost Callback  I need a collection with parsed elements  NAME               VALUE ------------------------ client id          SS response type      code scope              N FULL access type        offline redirect uri       http   localhost Callback  To be exact  I need a Java equivalent for the C   NET HttpUtility ParseQueryString method

User · Accepted Answer

If you are looking for a way to achieve it without using an external library, the following code will help you.

public static Map<String, String> splitQuery(URL url) throws UnsupportedEncodingException {
    Map<String, String> query_pairs = new LinkedHashMap<String, String>();
    String query = url.getQuery();
    String[] pairs = query.split("&");
    for (String pair : pairs) {
        int idx = pair.indexOf("=");
        query_pairs.put(URLDecoder.decode(pair.substring(0, idx), "UTF-8"), URLDecoder.decode(pair.substring(idx + 1), "UTF-8"));
    }
    return query_pairs;
}

You can access the returned Map using <map>.get("client_id"), with the URL given in your question this would return "SS".

UPDATE URL-Decoding added

UPDATE As this answer is still quite popular, I made an improved version of the method above, which handles multiple parameters with the same key and parameters with no value as well.

public static Map<String, List<String>> splitQuery(URL url) throws UnsupportedEncodingException {
  final Map<String, List<String>> query_pairs = new LinkedHashMap<String, List<String>>();
  final String[] pairs = url.getQuery().split("&");
  for (String pair : pairs) {
    final int idx = pair.indexOf("=");
    final String key = idx > 0 ? URLDecoder.decode(pair.substring(0, idx), "UTF-8") : pair;
    if (!query_pairs.containsKey(key)) {
      query_pairs.put(key, new LinkedList<String>());
    }
    final String value = idx > 0 && pair.length() > idx + 1 ? URLDecoder.decode(pair.substring(idx + 1), "UTF-8") : null;
    query_pairs.get(key).add(value);
  }
  return query_pairs;
}

UPDATE Java8 version

public Map<String, List<String>> splitQuery(URL url) {
    if (Strings.isNullOrEmpty(url.getQuery())) {
        return Collections.emptyMap();
    }
    return Arrays.stream(url.getQuery().split("&"))
            .map(this::splitQueryParameter)
            .collect(Collectors.groupingBy(SimpleImmutableEntry::getKey, LinkedHashMap::new, mapping(Map.Entry::getValue, toList())));
}

public SimpleImmutableEntry<String, String> splitQueryParameter(String it) {
    final int idx = it.indexOf("=");
    final String key = idx > 0 ? it.substring(0, idx) : it;
    final String value = idx > 0 && it.length() > idx + 1 ? it.substring(idx + 1) : null;
    return new SimpleImmutableEntry<>(
        URLDecoder.decode(key, "UTF-8"),
        URLDecoder.decode(value, "UTF-8")
    );
}

Running the above method with the URL

https://stackoverflow.com?param1=value1&param2=&param3=value3&param3

returns this Map:

{param1=["value1"], param2=[null], param3=["value3", null]}

User · Answer

If you are using Spring Framework   public static void main String   args        String uri    http   my test com test param1 ab amp param2 cd amp param2 ef       MultiValueMap lt String  String gt  parameters               UriComponentsBuilder fromUriString uri  build   getQueryParams        List lt String gt  param1   parameters get  param1        List lt String gt  param2   parameters get  param2        System out println  param1      param1 get 0        System out println  param2      param2 get 0          param2 get 1        You will get   param1  ab param2  cd ef

User · Answer

PLAIN Java 11 Given the URL to analyse  URL url   new URL  quot https   google com ua oauth authorize client id SS amp response type code amp scope N FULL amp access type offline amp redirect uri http   localhost Callback quot     This solution collects a list of pairs  List lt Map Entry lt String  String gt  gt  list   Pattern compile  quot  amp  quot       splitAsStream url getQuery        map s - gt  Arrays copyOf s split  quot   quot   2   2       map o - gt  Map entry decode o 0    decode o 1         collect Collectors toList      This solution on the other hand collects a map  given that in a url there can be more parameters with same name but different values   Map lt String  List lt String gt  gt  list   Pattern compile  quot  amp  quot       splitAsStream url getQuery        map s - gt  Arrays copyOf s split  quot   quot   2   2       collect groupingBy s - gt  decode s 0    mapping s - gt  decode s 1    toList        Both the solutions must use an utility function to properly decode the parameters  private static String decode final String encoded        return Optional ofNullable encoded                      map e - gt  URLDecoder decode e  StandardCharsets UTF 8                       orElse null

User · Answer

Here is my solution with reduce and Optional   private Optional lt SimpleImmutableEntry lt String  String gt  gt  splitKeyValue String text        String   v   text split           if  v length    1    v length    2            String key   URLDecoder decode v 0   StandardCharsets UTF 8           String value   v length    2   URLDecoder decode v 1   StandardCharsets UTF 8    null          return Optional of new SimpleImmutableEntry lt String  String gt  key  value          else         return Optional empty       private HashMap lt String  String gt  parseQuery URI uri        HashMap lt String  String gt  params   Arrays stream uri getQuery                split   amp                  map this  splitKeyValue               filter Optional  isPresent               map Optional  get               reduce                     initial value                 new HashMap lt String  String gt                         accumulator                  map  kv  - gt                         map put kv getKey    kv getValue                           return map                                         combiner                  a  b  - gt                         a putAll b                         return a                          return params       I ignore duplicate parameters  I take the last one   I use Optional lt SimpleImmutableEntry lt String  String gt  gt  to ignore garbage later The reduction start with an empty map  then populate it on each SimpleImmutableEntry   In case you ask  reduce requires this weird combiner in the last parameter  which is only used in parallel streams  Its goal is to merge two intermediate results  here HashMap

User · Answer

A ready-to-use solution for decoding of URI query part  incl  decoding and multi parameter values   Comments  I wasn t happy with the code provided by  Pr0gr4mm3r in https   stackoverflow com a 13592567 1211082   The Stream-based solution does not do URLDecoding  the mutable version clumpsy   Thus I elaborated a solution that   Can decompose a URI query part into a Map lt String  List lt Optional lt String gt  gt  gt  Can handle multiple values for the same parameter name Can represent parameters without a value properly   Optional empty   instead of null  Decodes parameter names and values correctly via URLdecode Is based on Java 8 Streams Is directly usable  see code including imports below  Allows for proper error handling  here via turning a checked exception UnsupportedEncodingExceptioninto a runtime exception RuntimeUnsupportedEncodingException that allows interplay with stream   Wrapping regular function into functions throwing checked exceptions is a pain  And Scala Try is not available in the Java language default     Java Code  import java io UnsupportedEncodingException  import java net URLDecoder  import java util    import static java util stream Collectors     public class URIParameterDecode                  Decode parameters in query part of a URI into a map from parameter name to its parameter values         For parameters that occur multiple times each value is collected         Proper decoding of the parameters is performed                 Example           lt pre gt a 1 amp b 2 amp c  amp a 4 lt  pre gt         is converted into           lt pre gt  a  Optional 1   Optional 4    b  Optional 2    c  Optional empty   lt  pre gt          param query the query part of an URI          return map of parameters names into a list of their values                              public static Map lt String  List lt Optional lt String gt  gt  gt  splitQuery String query            if  query    null    query isEmpty                  return Collections emptyMap                       return Arrays stream query split   amp                          map p - gt  splitQueryParameter p                        collect groupingBy e - gt  e get0       group by parameter name                             mapping e - gt  e get1    toList         keep parameter values and assemble into list            public static Pair lt String  Optional lt String gt  gt  splitQueryParameter String parameter            final String enc    UTF-8           List lt String gt  keyValue   Arrays stream parameter split                        map e - gt                        try                           return URLDecoder decode e  enc                         catch  UnsupportedEncodingException ex                            throw new RuntimeUnsupportedEncodingException ex                                            collect toList              if  keyValue size      2                return new Pair keyValue get 0   Optional of keyValue get 1               else               return new Pair keyValue get 0   Optional empty                              Runtime exception  instead of checked exception  to denote unsupported enconding        public static class RuntimeUnsupportedEncodingException extends RuntimeException           public RuntimeUnsupportedEncodingException Throwable cause                super cause                                   A simple pair of two elements         param  lt U gt  first element         param  lt V gt  second element             public static class Pair lt U  V gt            U a          V b           public Pair U u  V v                this a   u              this b   v                     public U get0                 return a                     public V get1                 return b                      Scala Code      and for the sake of completeness I can not resist to provide the solution in Scala that dominates by brevity and beauty  import java net URLDecoder  object Decode     def main args  Array String    Unit         val input    a 1 amp b 2 amp c  amp a 4       println separate input          def separate input  String    Map String  List Option String            case class Parameter key  String  value  Option String        def separateParameter parameter  String    Parameter         parameter split                      map e   gt  URLDecoder decode e   UTF-8    match         case Array key  value    gt   Parameter key  Some value         case Array key    gt  Parameter key  None             input split   amp    toList        map p   gt  separateParameter p          groupBy p   gt  p key         mapValues vs   gt  vs map p   gt  p value

User · Answer

If you happen to have cxf-core on the classpath and you know you have no repeated query params  you may want to use UrlUtils parseQueryString

User · Answer

I had a go at a Kotlin version seeing how this is the top result in Google    Throws UnsupportedEncodingException  class  fun splitQuery url  URL   Map lt String  List lt String gt  gt         val queryPairs   LinkedHashMap lt String  ArrayList lt String gt  gt         url query split   amp   toRegex                 dropLastWhile   it isEmpty                  map   it split                     map   it getOrEmpty 0  decodeToUTF8   to it getOrEmpty 1  decodeToUTF8                  forEach    key  value  - gt                   if   queryPairs containsKey key                         queryPairs key    arrayListOf value                    else                        if  queryPairs key    contains value                             queryPairs key    add value                                                             return queryPairs     And the extension methods  fun List lt String gt  getOrEmpty index  Int    String       return getOrElse index          fun String decodeToUTF8    String        URLDecoder decode this   UTF-8

User · Answer

On Android  there is a Uri class in package android net   Note that Uri is part of android net  while URI is part of java net    Uri class has many functions to extract key-value pairs from a query    Following function returns key-value pairs in the form of HashMap   In Java   Map lt String  String gt  getQueryKeyValueMap Uri uri       HashMap lt String  String gt  keyValueMap   new HashMap        String key      String value       Set lt String gt  keyNamesList   uri getQueryParameterNames        Iterator iterator   keyNamesList iterator         while  iterator hasNext             key    String  iterator next            value   uri getQueryParameter key           keyValueMap put key  value             return keyValueMap      In Kotlin   fun getQueryKeyValueMap uri  Uri   HashMap lt String  String gt            val keyValueMap   HashMap lt String  String gt            var key  String         var value  String          val keyNamesList   uri queryParameterNames         val iterator   keyNamesList iterator            while  iterator hasNext                  key   iterator next   as String             value   uri getQueryParameter key  as String             keyValueMap put key  value                    return keyValueMap

User · Answer

Netty also provides a nice query string parser called QueryStringDecoder  In one line of code  it can parse the URL in the question  I like because it doesn t require catching or throwing java net MalformedURLException   In one line   Map lt String  List lt String gt  gt  parameters   new QueryStringDecoder url  parameters      See javadocs here  https   netty io 4 1 api io netty handler codec http QueryStringDecoder html  Here is a short  self contained  correct example   import io netty handler codec http QueryStringDecoder  import org apache commons lang3 StringUtils   import java util List  import java util Map   public class UrlParse      public static void main String    args        String url    https   google com ua oauth authorize client id SS amp response type code amp scope N FULL amp access type offline amp redirect uri http   localhost Callback       QueryStringDecoder decoder   new QueryStringDecoder url       Map lt String  List lt String gt  gt  parameters   decoder parameters        print parameters          private static void print final Map lt String  List lt String gt  gt  parameters        System out println  NAME               VALUE        System out println  ------------------------        parameters forEach  key  values  - gt          values forEach val - gt              System out println StringUtils rightPad key  19    val             which generates  NAME               VALUE ------------------------ client id          SS response type      code scope              N FULL access type        offline redirect uri       http   localhost Callback

User · Answer

Kotlin s Answer with initial reference from https   stackoverflow com a 51024552 3286489  but with improved version by tidying up codes and provides 2 versions of it  and use immutable collection operations  Use java net URI to extract the Query  Then use the below provided extension functions   Assuming you only want the last value of query i e  page2 amp page3 will get  page 3   use the below extension function       fun URI getQueryMap    Map lt String  String gt            if  query    null  return emptyMap            return query split   amp                     mapNotNull   element - gt  element split                               takeIf   it size    2  amp  amp  it none   it isBlank                          associateBy   it 0  decodeUTF8        it 1  decodeUTF8                 private fun String decodeUTF8     URLDecoder decode this   UTF-8      decode page  22ABC 22 to page  ABC     Assuming you want a list of all value for the query i e  page2 amp page3 will get  page  2  3         fun URI getQueryMapList    Map lt String  List lt String gt  gt            if  query    null  return emptyMap            return query split   amp                     distinct                    mapNotNull   element - gt  element split                               takeIf   it size    2  amp  amp  it none   it isBlank                          groupBy   it 0  decodeUTF8        it 1  decodeUTF8                 private fun String decodeUTF8     URLDecoder decode this   UTF-8      decode page  22ABC 22 to page  ABC    The way to use it as below      val uri   URI  schema   host path  page  amp page 2 amp page 2 amp page 3       println uri getQueryMapList       Result is  page  2  3       println uri getQueryMap       Result is  page 3

User · Answer

Answering here because this is a popular thread   This is a clean solution in Kotlin that uses the recommended UrlQuerySanitizer api  See the official documentation   I have added a string builder to concatenate and display the params        var myURL  String    null      if  intent hasExtra  my value              myURL   intent extras getString  my value         else           myURL   intent dataString            val sanitizer   UrlQuerySanitizer myURL         We don t want to manually define every expected query  key   so we set this to true     sanitizer allowUnregisteredParamaters   true     val parameterNamesToValues  List lt UrlQuerySanitizer ParameterValuePair gt    sanitizer parameterList     val parameterIterator  Iterator lt UrlQuerySanitizer ParameterValuePair gt    parameterNamesToValues iterator           Helper simply so we can display all values on screen     val stringBuilder   StringBuilder        while  parameterIterator hasNext              val parameterValuePair  UrlQuerySanitizer ParameterValuePair   parameterIterator next           val parameterName  String   parameterValuePair mParameter         val parameterValue  String   parameterValuePair mValue             Append string to display all key value pairs         stringBuilder append  Key   parameterName nValue   parameterValue n n                 Set a textView s text to display the string     val paramListString   stringBuilder toString       val textView  TextView   findViewById R id activity title  as TextView     textView text    Paramlist is  n n paramListString          to check if the url has specific keys     if  sanitizer hasParameter  type              val type   sanitizer getValue  type           println  sanitizer has type param  type

User · Answer

If you come across Android Java SDK  This solution might be too late but it s the latest solution today  You can use the below way to get the value of the some query  if there is no value it will return null  String some   Uri parse url  getQueryParameter  quot some quot     In order to get all the names of the query collection  Set lt String gt  names   Uri parse url  getQueryParameterNames

User · Answer

If you re using Java 8 and you re willing to write a few reusable methods  you can do it in one line   private Map lt String  List lt String gt  gt  parse final String query        return Arrays asList query split   amp     stream   map p - gt  p split       collect Collectors toMap s - gt  decode index s  0    s - gt  Arrays asList decode index s  1     this  mergeLists       private  lt T gt  List lt T gt  mergeLists final List lt T gt  l1  final List lt T gt  l2        List lt T gt  list   new ArrayList lt  gt         list addAll l1       list addAll l2       return list     private static  lt T gt  T index final T   array  final int index        return index  gt   array length   null   array index      private static String decode final String encoded        try           return encoded    null   null   URLDecoder decode encoded   UTF-8          catch final UnsupportedEncodingException e            throw new RuntimeException  Impossible  UTF-8 is a required encoding   e             But that s a pretty brutal line

User · Answer

For Android  if you are using OkHttp in your project  You might get a look at this  It simple and helpful    final HttpUrl url   HttpUrl parse query   if  url    null        final String target   url queryParameter  target        final String id   url queryParameter  id

User · Answer

The shortest way I ve found is this one   MultiValueMap lt String  String gt  queryParams               UriComponentsBuilder fromUriString url  build   getQueryParams      UPDATE  UriComponentsBuilder comes from Spring  Here the link

User · Answer

Just an update to the Java 8 version  public Map lt String  List lt String gt  gt  splitQuery URL url        if  Strings isNullOrEmpty url getQuery               return Collections emptyMap              return Arrays stream url getQuery   split   amp                  map this  splitQueryParameter               collect Collectors groupingBy SimpleImmutableEntry  getKey  LinkedHashMap  new    Collectors   mapping Map Entry  getValue    Collectors   toList           mapping and toList   methods have to be used with Collectors which was not mentioned in the top answer  Otherwise it would throw compilation error in IDE

User · Answer

If you are using servlet doGet try this  request getParameterMap        Returns a java util Map of the parameters of this request       Returns    an immutable java util Map containing parameter names as keys and parameter values as map values  The keys in the parameter map are of type String  The values in the parameter map are of type String array        Java doc

User · Answer

org apache http client utils URLEncodedUtils is a well known library that can do it for you import org apache hc client5 http utils URLEncodedUtils  String url    quot http   www example com something html one 1 amp two 2 amp three 3 amp three 3a quot    List lt NameValuePair gt  params   URLEncodedUtils parse new URI url   Charset forName  quot UTF-8 quot      for  NameValuePair param   params      System out println param getName      quot     quot    param getValue        Outputs one   1 two   2 three   3 three   3a

User · Answer

If you are using Spring  add an argument of type  RequestParam Map lt String String gt   to your controller method  and Spring will construct the map for you

User · Answer

use google Guava and do it in 2 lines   import java util Map  import com google common base Splitter   public class Parser       public static void main String    args            String uri    https   google com ua oauth authorize client id SS amp response type code amp scope N FULL amp access type offline amp redirect uri http   localhost Callback           String query   uri split        1           final Map lt String  String gt  map   Splitter on   amp    trimResults   withKeyValueSeparator      split query           System out println map             which gives you   client id SS  response type code  scope N FULL  access type offline  redirect uri http   localhost Callback

User · Answer

Using above mentioned comments and solutions  I am storing all the query parameters using Map lt String  Object gt  where Objects either can be string or Set lt String gt   The solution is given below  It is recommended to use some kind of url validator to validate the url first and then call convertQueryStringToMap method    private static final String DEFAULT ENCODING SCHEME    UTF-8    public static Map lt String  Object gt  convertQueryStringToMap String url  throws UnsupportedEncodingException  URISyntaxException       List lt NameValuePair gt  params   URLEncodedUtils parse new URI url   DEFAULT ENCODING SCHEME       Map lt String  Object gt  queryStringMap   new HashMap lt  gt         for NameValuePair param   params           queryStringMap put param getName    handleMultiValuedQueryParam queryStringMap  param getName    param getValue                return queryStringMap     private static Object handleMultiValuedQueryParam Map responseMap  String key  String value        if   responseMap containsKey key             return value contains        new HashSet lt String gt  Arrays asList value split          value        else           Set lt String gt  queryValueSet   responseMap get key  instanceof Set    Set lt String gt   responseMap get key    new HashSet lt String gt             if  value contains                     queryValueSet addAll Arrays asList value split                   else               queryValueSet add value                     return queryValueSet

[java] Parse a URI String into Name-Value Collection

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