How to convert XML to java util Map and vice versa

Question

I m searching a lightweight API  preferable single class  to convert a  Map lt String String gt  map   new HashMap lt String String      to xml and  vice versa  convert the XML back to a Map   example   Map lt String String gt  map   new HashMap lt String String    map put  name   chris    map put  island   faranga     MagicAPI toXML map  root      result    lt root gt     lt name gt chris lt  chris gt     lt island gt faranga lt  island gt   lt  root gt    and back   Map lt String String gt  map   MagicAPI fromXML           I dont want to use JAXB or JSON conversion API  It doesnt have to take care of nested maps or attributes or anything else  just that simple case  Any suggestions     Edit  I created a working copy  amp  paste sample  Thanks to fvu and Michal Bernhard   Download latest XStream framework   core only  is enough   Map lt String Object gt  map   new HashMap lt String Object gt     map put  name   chris    map put  island   faranga        convert to XML XStream xStream   new XStream new DomDriver     xStream alias  map   java util Map class   String xml   xStream toXML map       from XML  convert back to map Map lt String Object gt  map2    Map lt String Object gt   xStream fromXML xml     No converters or anything else is required  Just the xstream-x y z jar is enough

User · Answer

Here the converter for XStream including unmarshall   public class MapEntryConverter implements Converter  public boolean canConvert Class clazz        return AbstractMap class isAssignableFrom clazz      public void marshal Object value  HierarchicalStreamWriter writer  MarshallingContext context        AbstractMap lt String String gt  map    AbstractMap lt String String gt   value      for  Entry lt String String gt  entry   map entrySet              writer startNode entry getKey   toString             writer setValue entry getValue   toString             writer endNode             public Object unmarshal HierarchicalStreamReader reader  UnmarshallingContext context        Map lt String  String gt  map   new HashMap lt String  String gt          while reader hasMoreChildren              reader moveDown            map put reader getNodeName    reader getValue             reader moveUp              return map

User · Answer

Underscore-java library can convert Map to xml  I am the maintainer of the project  Live example Code example  import com github underscore lodash U  import java util         public class Main      public static void main String   args             Map lt String  Object gt  map   new LinkedHashMap lt String  Object gt         map put  quot name quot    quot chris quot        map put  quot island quot    quot faranga quot         System out println U toXml map              lt  xml version  quot 1 0 quot  encoding  quot UTF-8 quot   gt           lt root gt             lt name gt chris lt  name gt             lt island gt faranga lt  island gt           lt  root gt          and back      map   U fromXmlMap  quot  lt  xml version   quot 1 0  quot  encoding   quot UTF-8  quot   gt  lt root gt  quot             quot      lt name gt chris lt  name gt  quot             quot      lt island gt faranga lt  island gt  quot             quot    lt  root gt  quot                 System out println map           name chris  island faranga

User · Answer

One option would be to roll your own  It would be fairly simple to do   Document doc   getDocument    Element root   doc createElement rootName   doc appendChild root   for  Map Entry lt String String gt  element   map entrySet           Element e   doc createElement element getKey         e setTextContent element getValue         root appendChild e     save doc  file     and the load is an equally simply getChildNodes and a loop  Sure it has a bit of boiler plate that the XML Gods demand but it is at most 1 hours work    Or you could look at Properties if you are not too fused about the format of the XML

User · Answer

If you only need to convert simple map to xml  without nested properties  then the lightweight solution would be just a private method  as follows   private String convertMapToXML Map lt String  String gt  map        StringBuilder xmlBuilder   new StringBuilder        xmlBuilder append   lt xml gt         for  Map Entry lt String  String gt  entry   map entrySet              if  entry getValue      null                String xmlElement   entry getKey                xmlBuilder append   lt                 xmlBuilder append xmlElement               xmlBuilder append   gt                 xmlBuilder append entry getValue                 xmlBuilder append   lt                 xmlBuilder append                   xmlBuilder append xmlElement                               xmlBuilder append   gt                                       xmlBuilder append   lt  xml gt         return xmlBuilder toString

User · Answer

XStream   Updated  I added unmarshal part as requested in comments    import com thoughtworks xstream XStream  import com thoughtworks xstream converters Converter  import com thoughtworks xstream converters MarshallingContext  import com thoughtworks xstream converters UnmarshallingContext  import com thoughtworks xstream io HierarchicalStreamReader  import com thoughtworks xstream io HierarchicalStreamWriter   import java util AbstractMap  import java util HashMap  import java util Map   public class Test        public static void main String   args             Map lt String String gt  map   new HashMap lt String String gt             map put  name   chris            map put  island   faranga             XStream magicApi   new XStream            magicApi registerConverter new MapEntryConverter             magicApi alias  root   Map class            String xml   magicApi toXML map           System out println  Result of tweaked XStream toXml              System out println xml            Map lt String  String gt  extractedMap    Map lt String  String gt   magicApi fromXML xml           assert extractedMap get  name   equals  chris            assert extractedMap get  island   equals  faranga                public static class MapEntryConverter implements Converter            public boolean canConvert Class clazz                return AbstractMap class isAssignableFrom clazz                      public void marshal Object value  HierarchicalStreamWriter writer  MarshallingContext context                 AbstractMap map    AbstractMap  value              for  Object obj   map entrySet                      Map Entry entry    Map Entry  obj                  writer startNode entry getKey   toString                     Object val   entry getValue                    if   null    val                         writer setValue val toString                                       writer endNode                                      public Object unmarshal HierarchicalStreamReader reader  UnmarshallingContext context                 Map lt String  String gt  map   new HashMap lt String  String gt                  while reader hasMoreChildren                      reader moveDown                     String key   reader getNodeName       nodeName aka element s name                 String value   reader getValue                    map put key  value                    reader moveUp                               return map

User · Answer

I used the approach with the custom converter   public static class MapEntryConverter implements Converter        public boolean canConvert Class clazz            return AbstractMap class isAssignableFrom clazz              public void marshal Object value  HierarchicalStreamWriter writer  MarshallingContext context             AbstractMap map    AbstractMap  value          for  Object obj   map entrySet                  Entry entry    Entry  obj              writer startNode entry getKey   toString                 context convertAnother entry getValue                 writer endNode                         public Object unmarshal HierarchicalStreamReader reader  UnmarshallingContext context               dunno  read manual and do it yourself               But i changed the the serialization of the maps value to delegate to the MarshallingContext  This should improve the solution to work for composite map values and nested maps as well

User · Answer

Now it s 2017  The latest version of XStream requires a converter to make it works as your expected    A converter supports nested map   public class MapEntryConverter implements Converter         Override     public void marshal Object value  HierarchicalStreamWriter writer  MarshallingContext marshallingContext            AbstractMap map    AbstractMap  value          for  Object obj   map entrySet                  Map Entry entry    Map Entry  obj              writer startNode entry getKey   toString                 Object val   entry getValue                if  val instanceof Map                    marshal val  writer  marshallingContext                 else if  null    val                    writer setValue val toString                               writer endNode                          Override     public Object unmarshal HierarchicalStreamReader reader  UnmarshallingContext unmarshallingContext            Map lt String  Object gt  map   new HashMap lt  gt              while reader hasMoreChildren                  reader moveDown                 String key   reader getNodeName       nodeName aka element s name             String value   reader getValue   replaceAll    n   t                    if  StringUtils isBlank value                     map put key  unmarshal reader  unmarshallingContext                  else                   map put key  value                              reader moveUp                       return map              Override     public boolean canConvert Class clazz            return AbstractMap class isAssignableFrom clazz

User · Answer

I have tried different kinds of maps and the Conversion Box worked  I have used your map and have pasted an example below with some inner maps  Hope it is helpful to you        import java util HashMap  import java util Map   import cjm component cb map ToMap  import cjm component cb xml ToXML   public class Testing   public static void main String   args        try               Map lt String  Object gt  map   new HashMap lt String  Object gt        ORIGINAL MAP          map put  name    chris            map put  island    faranga             Map lt String  String gt  mapInner   new HashMap lt String  String gt        SAMPLE INNER MAP          mapInner put  a    A            mapInner put  b    B            mapInner put  c    C             map put  innerMap   mapInner            Map lt String  Object gt  mapRoot   new HashMap lt String  Object gt        ROOT MAP          mapRoot put  ROOT   map            System out println  Map      mapRoot            System out println             ToXML toXML   new ToXML             String convertedXML   String valueOf toXML convertToXML mapRoot  true       CONVERTING ROOT MAP TO XML          System out println  Converted XML      convertedXML            System out println             ToMap toMap   new ToMap             Map lt String  Object gt  convertedMap   toMap convertToMap convertedXML      CONVERTING CONVERTED XML BACK TO MAP          System out println  Converted Map      convertedMap             catch  Exception e                e printStackTrace                Output   Map   ROOT  name chris  innerMap  b B  c C  a A   island faranga     -------- Map Detected --------   -------- XML created Successfully --------  Converted XML   lt ROOT gt  lt name gt chris lt  name gt  lt innerMap gt  lt b gt B lt  b gt  lt c gt C lt  c gt  lt a gt A lt  a gt  lt  innerMap gt  lt island gt faranga lt  island gt  lt  ROOT gt    -------- XML Detected --------   -------- Map created Successfully --------  Converted Map   ROOT  name chris  innerMap  b B  c C  a A   island faranga

User · Answer

I found this on google  but I don t want to use XStream  because it causes to much overhead in my environment  I only needed to parse a file and since I did not find anything I like I created my own simple solution for parsing a file of the format that you describe  So here is my solution   public class XmlToMapUtil       public static Map lt String  String gt  parse InputSource inputSource  throws SAXException  IOException  ParserConfigurationException           final DataCollector handler   new DataCollector            SAXParserFactory newInstance   newSAXParser   parse inputSource  handler           return handler result             private static class DataCollector extends DefaultHandler           private final StringBuilder buffer   new StringBuilder            private final Map lt String  String gt  result   new HashMap lt String  String gt               Override         public void endElement String uri  String localName  String qName  throws SAXException               final String value   buffer toString   trim                if  value length    gt  0                    result put qName  value                             buffer setLength 0                       Override         public void characters char   ch  int start  int length  throws SAXException               buffer append ch  start  length                       Here are a couple of TestNG FEST Assert Tests   public class XmlToMapUtilTest         Test dataProvider    provide xml entries       public void parse returnsMapFromXml String xml  MapAssert Entry   entries  throws Exception              execution         final Map lt String  String gt  actual   XmlToMapUtil parse new InputSource new StringReader xml                 evaluation         assertThat actual               includes entries               hasSize entries length               DataProvider     public Object     provide xml entries             return new Object                         lt root   gt    new MapAssert Entry 0                                             lt root gt  lt a gt aVal lt  a gt  lt  root gt    new MapAssert Entry                                MapAssert entry  a    aVal                                                                                      lt root gt  lt a gt aVal lt  a gt  lt b gt bVal lt  b gt  lt  root gt    new MapAssert Entry                                MapAssert entry  a    aVal                                MapAssert entry  b    bVal                                                                                      lt root gt   t  lt a gt  taVal  lt  a gt  lt b   gt  lt  root gt    new MapAssert Entry                                MapAssert entry  a    aVal

User · Answer

In my case I convert DBresponse to XML in Camel ctx  JDBC executor return the ArrayList  rows   with LinkedCaseInsensitiveMap  single row    Task - create XML object based on DBResponce    import java io StringWriter  import java util ArrayList  import javax xml parsers DocumentBuilder  import javax xml parsers DocumentBuilderFactory  import javax xml parsers ParserConfigurationException  import javax xml transform OutputKeys  import javax xml transform Transformer  import javax xml transform TransformerFactory  import javax xml transform dom DOMSource  import javax xml transform stream StreamResult   import org springframework util LinkedCaseInsensitiveMap  import org w3c dom Document  import org w3c dom Element  import org w3c dom Node   public class ConvertDBToXMLProcessor implements Processor        public void process List body             if  body instanceof ArrayList                ArrayList lt LinkedCaseInsensitiveMap gt  rows    ArrayList  body               DocumentBuilder builder   null              builder   DocumentBuilderFactory newInstance   newDocumentBuilder                Document document   builder newDocument                Element rootElement   document createElement  DBResultSet                 for  LinkedCaseInsensitiveMap row   rows                    Element newNode   document createElement  Row                    row forEach  key  value  - gt                        if  value    null                            Element newKey   document createElement  String  key                           newKey setTextContent value toString                             newNode appendChild newKey                                                             rootElement appendChild newNode                             document appendChild rootElement                                   If you need return string view instead org w3c dom Document                            StringWriter writer   new StringWriter                StreamResult result   new StreamResult writer               DOMSource domSource   new DOMSource document               TransformerFactory tf   TransformerFactory newInstance                Transformer transformer   tf newTransformer                transformer setOutputProperty OutputKeys INDENT   yes                transformer setOutputProperty OutputKeys OMIT XML DECLARATION   no                transformer transform domSource  result                   return document                return writer toString

User · Answer

How about XStream   Not 1 class but 2 jars for many use cases including yours  very simple to use yet quite  powerful

User · Answer

I have written a piece of code that transforms a XML content into a multi-layer structure of maps   public static Object convertNodesFromXml String xml  throws Exception        InputStream is   new ByteArrayInputStream xml getBytes         DocumentBuilderFactory dbf   DocumentBuilderFactory newInstance        dbf setNamespaceAware true       DocumentBuilder db   dbf newDocumentBuilder        Document document   db parse is       return createMap document getDocumentElement        public static Object createMap Node node        Map lt String  Object gt  map   new HashMap lt String  Object gt         NodeList nodeList   node getChildNodes        for  int i   0  i  lt  nodeList getLength    i              Node currentNode   nodeList item i           String name   currentNode getNodeName            Object value   null          if  currentNode getNodeType      Node ELEMENT NODE                value   createMap currentNode                     else if  currentNode getNodeType      Node TEXT NODE                return currentNode getTextContent                      if  map containsKey name                 Object os   map get name               if  os instanceof List                      List lt Object gt  os  add value                             else                   List lt Object gt  objs   new LinkedList lt Object gt                     objs add os                   objs add value                   map put name  objs                                   else               map put name  value                       return map      This code transforms this    lt house gt       lt door gt blue lt  door gt       lt living-room gt           lt table gt wood lt  table gt           lt chair gt wood lt  chair gt       lt  living-room gt   lt  house gt    into         house              door    blue            living-room                  table    wood                chair    wood                        I don t have the inverse process  but that must not be very difficult to write

User · Answer

I am posting this as an answer not because it s the correct answer to your question  but because it s a solution to the same problem  but using attributes instead  Otherwise Vikas Gujjar s answer is correct   Quite oftern your data could be in attributes  but it s quite hard to find any working examples using XStream to do this  so here s one   Sample data    lt settings gt       lt property name  prop1  value  foo   gt       lt property name  prop2    gt   lt  -- NOTE                                     The example supports null elements as                                    the backing object is a HashMap                                     A Properties object would be handled                                    by a PropertiesConverter which wouldn t                                    allow you null values   -- gt       lt property name  prop3  value  1   gt   lt  settings gt    Implementation of MapEntryConverter  slightly re-worked  Vikas Gujjar s implementation to use attributes instead    public class MapEntryConverter         implements Converter        public boolean canConvert Class clazz                return AbstractMap class isAssignableFrom clazz              public void marshal Object value                          HierarchicalStreamWriter writer                          MarshallingContext context                  noinspection unchecked         AbstractMap lt String  String gt  map    AbstractMap lt String  String gt   value          for  Map Entry lt String  String gt  entry   map entrySet                            noinspection RedundantStringToString             writer startNode entry getKey   toString                   noinspection RedundantStringToString             writer setValue entry getValue   toString                 writer endNode                         public Object unmarshal HierarchicalStreamReader reader                              UnmarshallingContext context                Map lt String  String gt  map   new HashMap lt String  String gt              while  reader hasMoreChildren                          reader moveDown                map put reader getAttribute  name    reader getAttribute  value                 reader moveUp                       return map            XStream instance setup  parsing and storing       XStream xstream   new XStream        xstream autodetectAnnotations true       xstream alias  settings   HashMap class       xstream registerConverter new MapEntryConverter                    Parse      YourObject yourObject    YourObject  xstream fromXML is          Store      xstream toXML yourObject

[java] How to convert XML to java.util.Map and vice versa

Examples related to java

Examples related to xml