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   1 package org.collectionspace.services.common.xmljson;
   2
   3 import java.io.IOException;
   4 import java.io.InputStream;
   5 import java.io.OutputStream;
   6 import java.io.PrintWriter;
   7 import java.util.Iterator;
   8 import java.util.Stack;
   9
  10 import javax.xml.namespace.QName;
  11 import javax.xml.stream.XMLEventReader;
  12 import javax.xml.stream.XMLInputFactory;
  13 import javax.xml.stream.XMLStreamConstants;
  14 import javax.xml.stream.XMLStreamException;
  15 import javax.xml.stream.events.Attribute;
  16 import javax.xml.stream.events.Namespace;
  17 import javax.xml.stream.events.StartElement;
  18 import javax.xml.stream.events.XMLEvent;
  19
  20 import org.apache.commons.lang3.StringUtils;
  21 import org.collectionspace.services.common.xmljson.parsetree.Node;
  22
  23 import com.fasterxml.jackson.core.JsonGenerationException;
  24 import com.fasterxml.jackson.databind.JsonMappingException;
  25 import com.fasterxml.jackson.databind.ObjectMapper;
  26
  27 public class XmlToJsonStreamConverter {
  28     protected XMLEventReader eventReader;
  29     protected PrintWriter writer;
  30     protected Stack<Node> stack = new Stack<Node>();
  31     protected Node parseResult = null;
  32
  33     public static String nodeNameForQName(QName name) {
  34         String prefix = name.getPrefix();
  35         String localPart = name.getLocalPart();
  36
  37         if (StringUtils.isNotEmpty(prefix)) {
  38             return prefix + ":" + localPart;
  39         }
  40
  41         return localPart;
  42     }
  43
  44     public XmlToJsonStreamConverter(InputStream in, OutputStream out) throws XMLStreamException {
  45         XMLInputFactory factory = XMLInputFactory.newInstance();
  46
  47         eventReader = factory.createXMLEventReader(in);
  48         writer = new PrintWriter(out);
  49     }
  50
  51     public void convert() throws XMLStreamException, JsonGenerationException, JsonMappingException, IOException {
  52         while(eventReader.hasNext()){
  53             XMLEvent event = eventReader.nextEvent();
  54
  55             switch(event.getEventType()) {
  56                 case XMLStreamConstants.CHARACTERS:
  57                     onCharacters(event);
  58                     break;
  59                 case XMLStreamConstants.START_ELEMENT:
  60                     onStartElement(event);
  61                     break;
  62                 case XMLStreamConstants.END_ELEMENT:
  63                     onEndElement(event);
  64                     break;
  65                 case XMLStreamConstants.START_DOCUMENT:
  66                     onStartDocument(event);
  67                     break;
  68                 case XMLStreamConstants.END_DOCUMENT:
  69                     onEndDocument(event);
  70                     break;
  71             }
  72         }
  73
  74         ObjectMapper objectMapper = new ObjectMapper();
  75         objectMapper.writeValue(writer, parseResult);
  76
  77         writer.flush();
  78     }
  79
  80     protected void onStartDocument(XMLEvent event) {
  81         stack.push(new Node());
  82     }
  83
  84     protected void onEndDocument(XMLEvent event) {
  85         parseResult = stack.pop();
  86     }
  87
  88     @SuppressWarnings("unchecked")
  89     protected void onStartElement(XMLEvent event) {
  90         StartElement element = event.asStartElement();
  91         QName name = element.getName();
  92
  93         Node node = new Node(nodeNameForQName(name));
  94
  95         Iterator<Attribute> attrIter = element.getAttributes();
  96
  97         while(attrIter.hasNext()) {
  98             Attribute attr = attrIter.next();
  99
 100             node.addAttribute(attr.getName().toString(), attr.getValue());
 101         }
 102
 103         Iterator<Namespace> nsIter = element.getNamespaces();
 104
 105         while(nsIter.hasNext()) {
 106             Namespace ns = nsIter.next();
 107
 108             node.addNamespace(ns.getPrefix(), ns.getNamespaceURI());
 109         }
 110
 111         stack.push(node);
 112     }
 113
 114     protected void onCharacters(XMLEvent event) {
 115         String text = event.asCharacters().getData();
 116         Node parent = stack.peek();
 117
 118         parent.addText(text);
 119     }
 120
 121     protected void onEndElement(XMLEvent event) {
 122         Node node = stack.pop();
 123         Node parent = stack.peek();
 124
 125         parent.addChild(node);
 126     }
 127 }