org.sapia.cocoon.serialization.json
Class JsonSerializer

java.lang.Object
  org.apache.avalon.framework.logger.AbstractLogEnabled
      org.apache.cocoon.xml.AbstractXMLProducer
          org.apache.cocoon.xml.AbstractXMLPipe
              org.apache.cocoon.serialization.AbstractSerializer
                  org.sapia.cocoon.serialization.json.JsonSerializer

All Implemented Interfaces:

org.apache.avalon.excalibur.pool.Poolable, org.apache.avalon.excalibur.pool.Recyclable, org.apache.avalon.framework.logger.LogEnabled, org.apache.cocoon.serialization.Serializer, org.apache.cocoon.sitemap.SitemapModelComponent, org.apache.cocoon.sitemap.SitemapOutputComponent, org.apache.cocoon.xml.XMLPipe, org.apache.cocoon.xml.XMLProducer, org.apache.excalibur.xml.sax.XMLConsumer, org.xml.sax.ContentHandler, org.xml.sax.ext.LexicalHandler

public class JsonSerializer
extends org.apache.cocoon.serialization.AbstractSerializer
implements org.apache.cocoon.sitemap.SitemapModelComponent

This serializer generates JSON data out of an XML document. The serializer has the following features/limitations:

• The serializer creates a JSON graph that maps the structure of the XML document: a JSON object is created for each XML element in the document.
• XML namespaces are ignored.
• A JSON array is created for child elements that have the same name, under a given parent element. If there is only one child element of a given name under another element, then no array is created (a single JSON object is created for that single child element).
• A "cdata" field is created to hold the content of the CDATA (text nested in a given XML element) of the corresponding XML element.

For example, given the following XML document:

 
   
     Dinner next week
   
 
 

Will yield the following JSON data:

 {
   "addressBook": {
     "contact": {
       "firstName": "bill", 
       "lastName": "gates", 
       "cdata": "Dinner next week"
     }
   }
 }
 

As the following XML:

Will yield:

 {
   "addressBook": {
     "contact": [
       { "firstName": "bill", "lastName": "gates" },
       { "firstName": "linus", "lastName": "torvalds" }       
     ]
   }
 }
 

Note that this serializer takes the following parameters (as part of the sitemap configuration):

• content-type: by default, set to application/json.
• global-var-name: the name of the Javascript global variable, if the JSON data is to be returned as a Javascript resource (see below for explanations).

This serializer allows for the JSON data to be sent as a Javascript resource (i.e.: the corresponding JSON may then included as a Javascript resource in a HTML page). For this to be possible, the JSON data is returned as a Javascript global variable - in this case, the global-var-name sitemap variable must be set and correspond to the name of the Javascript variable that will be sent to the browser. For example, given our address book data (see above), setting the global-var-name parameter to AddressBookData would trigger the generation of the following data:

 AddressBookData = {
   "addressBook": {
     "contact": [
       { "firstName": "bill", "lastName": "gates" },
       { "firstName": "linus", "lastName": "torvalds" }       
     ]
   }
 }
 

Example Spring configuration:

Example Sitemap configuration:

      
        
        
Field Summary




static java.lang.String
MIME_TYPE_JSON



           



static java.lang.String
PARAM_CONTENT_TYPE



           



static java.lang.String
PARAM_GLOBAL_VAR_NAME



           


 
Fields inherited from class org.apache.cocoon.serialization.AbstractSerializer
output
 
Fields inherited from class org.apache.cocoon.xml.AbstractXMLProducer
contentHandler, EMPTY_CONTENT_HANDLER, lexicalHandler, xmlConsumer
 
Fields inherited from interface org.apache.cocoon.serialization.Serializer
ROLE
 



Constructor Summary
JsonSerializer()



           
 



Method Summary




 void
characters(char[] ch,
           int start,
           int length)



           



 void
endDocument()



           



 void
endElement(java.lang.String uri,
           java.lang.String localName,
           java.lang.String qName)



           



 java.lang.String
getMimeType()



           



 void
recycle()



           



 void
setOutputStream(java.io.OutputStream ous)



           



 void
setup(org.apache.cocoon.environment.SourceResolver resolver,
      java.util.Map objectModel,
      java.lang.String src,
      org.apache.avalon.framework.parameters.Parameters parameters)



           



 boolean
shouldSetContentLength()



           



 void
startDocument()



           



 void
startElement(java.lang.String uri,
             java.lang.String localName,
             java.lang.String qname,
             org.xml.sax.Attributes attrs)



           


 
Methods inherited from class org.apache.cocoon.xml.AbstractXMLPipe
comment, endCDATA, endDTD, endEntity, endPrefixMapping, ignorableWhitespace, processingInstruction, setDocumentLocator, skippedEntity, startCDATA, startDTD, startEntity, startPrefixMapping
 
Methods inherited from class org.apache.cocoon.xml.AbstractXMLProducer
setConsumer, setContentHandler, setLexicalHandler
 
Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled
enableLogging, getLogger, setupLogger, setupLogger, setupLogger
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.xml.sax.ContentHandler
endPrefixMapping, ignorableWhitespace, processingInstruction, setDocumentLocator, skippedEntity, startPrefixMapping
 
Methods inherited from interface org.xml.sax.ext.LexicalHandler
comment, endCDATA, endDTD, endEntity, startCDATA, startDTD, startEntity
 
Methods inherited from interface org.apache.cocoon.xml.XMLProducer
setConsumer
 





Field Detail



PARAM_GLOBAL_VAR_NAME
public static final java.lang.String PARAM_GLOBAL_VAR_NAME


See Also:
Constant Field Values




PARAM_CONTENT_TYPE
public static final java.lang.String PARAM_CONTENT_TYPE


See Also:
Constant Field Values




MIME_TYPE_JSON
public static final java.lang.String MIME_TYPE_JSON


See Also:
Constant Field Values





Constructor Detail



JsonSerializer
public JsonSerializer()






Method Detail



setup
public void setup(org.apache.cocoon.environment.SourceResolver resolver,
                  java.util.Map objectModel,
                  java.lang.String src,
                  org.apache.avalon.framework.parameters.Parameters parameters)
           throws org.apache.cocoon.ProcessingException,
                  org.xml.sax.SAXException,
                  java.io.IOException


Specified by:
setup in interface org.apache.cocoon.sitemap.SitemapModelComponent



Throws:
org.apache.cocoon.ProcessingException
org.xml.sax.SAXException
java.io.IOException





recycle
public void recycle()


Specified by:
recycle in interface org.apache.avalon.excalibur.pool.Recyclable
Overrides:
recycle in class org.apache.cocoon.serialization.AbstractSerializer








getMimeType
public java.lang.String getMimeType()


Specified by:
getMimeType in interface org.apache.cocoon.sitemap.SitemapOutputComponent
Overrides:
getMimeType in class org.apache.cocoon.serialization.AbstractSerializer








setOutputStream
public void setOutputStream(java.io.OutputStream ous)
                     throws java.io.IOException


Specified by:
setOutputStream in interface org.apache.cocoon.sitemap.SitemapOutputComponent
Overrides:
setOutputStream in class org.apache.cocoon.serialization.AbstractSerializer



Throws:
java.io.IOException





startElement
public void startElement(java.lang.String uri,
                         java.lang.String localName,
                         java.lang.String qname,
                         org.xml.sax.Attributes attrs)
                  throws org.xml.sax.SAXException


Specified by:
startElement in interface org.xml.sax.ContentHandler
Overrides:
startElement in class org.apache.cocoon.xml.AbstractXMLPipe



Throws:
org.xml.sax.SAXException





endElement
public void endElement(java.lang.String uri,
                       java.lang.String localName,
                       java.lang.String qName)
                throws org.xml.sax.SAXException


Specified by:
endElement in interface org.xml.sax.ContentHandler
Overrides:
endElement in class org.apache.cocoon.xml.AbstractXMLPipe



Throws:
org.xml.sax.SAXException





startDocument
public void startDocument()
                   throws org.xml.sax.SAXException


Specified by:
startDocument in interface org.xml.sax.ContentHandler
Overrides:
startDocument in class org.apache.cocoon.xml.AbstractXMLPipe



Throws:
org.xml.sax.SAXException





endDocument
public void endDocument()
                 throws org.xml.sax.SAXException


Specified by:
endDocument in interface org.xml.sax.ContentHandler
Overrides:
endDocument in class org.apache.cocoon.xml.AbstractXMLPipe



Throws:
org.xml.sax.SAXException





characters
public void characters(char[] ch,
                       int start,
                       int length)
                throws org.xml.sax.SAXException


Specified by:
characters in interface org.xml.sax.ContentHandler
Overrides:
characters in class org.apache.cocoon.xml.AbstractXMLPipe



Throws:
org.xml.sax.SAXException





shouldSetContentLength
public boolean shouldSetContentLength()


Specified by:
shouldSetContentLength in interface org.apache.cocoon.sitemap.SitemapOutputComponent
Overrides:
shouldSetContentLength in class org.apache.cocoon.serialization.AbstractSerializer