org.jolokia.converter.json

Class TabularDataExtractor

java.lang.Object

org.jolokia.converter.json.TabularDataExtractor

All Implemented Interfaces:

Extractor

public class TabularDataExtractor
extends Object
implements Extractor

Since:

Apr 19, 2009

Author:

roland

Constructor Summary

Constructors

Constructor and Description
TabularDataExtractor()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	canSetValue() Whether this extractor is able to set a value.
Object	extractObject(ObjectToJsonConverter pConverter, Object pValue, Stack<String> pPathParts, boolean pJsonify) Extract a TabularData.
Class	getType() Type for which this extractor can objects of this type
Object	setObjectValue(StringToObjectConverter pConverter, Object pInner, String pAttribute, Object pValue) Throws always IllegalArgumentException since tabular data is immutable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

TabularDataExtractor

public TabularDataExtractor()

Method Detail

getType

public Class getType()

Type for which this extractor can objects of this type

Specified by:

getType in interface Extractor

Returns:

type which can be handled

extractObject

public Object extractObject(ObjectToJsonConverter pConverter,
                   Object pValue,
                   Stack<String> pPathParts,
                   boolean pJsonify)
                     throws AttributeNotFoundException

Extract a TabularData. The JSON representation of a tabular data is different, depending on whether it represents a map for an MXBean or is a regular data.

I.e. for an tabular data which have a row type with two column "key" and "value", then a map is returned (with the "key" values as map keys and "value" values as map values).

Otherwise a map of (one or more) maps is returned, where the map keys are taken from TabularType of the presented data. E.g. if there is a single valued key "key", then the returned JSON looks like

      {
         "mykey1" : { "key" : "mkey1", "item" : "value1", .... }
         "mykey2" : { "key" : "mkey2", "item" : "value2", .... }
         ....
      }
  

For multi valued keys of simple open types (i.e. TabularType.getIndexNames() is a list with more than one element), the returned JSON structure looks like (index names here are "key" and "innerkey")

      {
         "mykey1" : {
                       "myinner1" : { "key" : "mkey1", "innerkey" : "myinner1", "item" : "value1", .... }
                       "myinner2" : { "key" : "mkey1", "innerkey" : "myinner2", "item" : "value1", .... }
                       ....
                     }
         "mykey2" : {
                       "second1" : { "key" : "mkey2", "innerkey" : "second1", "item" : "value1", .... }
                       "second2" : { "key" : "mkey2", "innerkey" : "second2", "item" : "value1", .... }
                       ....
                    }
         ....
      }
  

If keys are used, which themselves are complex objects (like composite data), this hierarchical map structure can not be used. In this case an object with two keys is returned: "indexNames" holds the name of the key index and "values" is an array of all rows which are represented as JSON objects:

      {
        "indexNames" : [ "key", "innerkey" ],
        "values" : [
           { "key" : "mykey1", "innerkey" : { "name" : "a", "number" : 4711 }, "item" : "value1", .... },
           { "key" : "mykey2", "innerkey" : { "name" : "b", "number" : 815 }, "item" : "value2", .... },
           ...
        ]
      }
  

Accessing TabularData with a path is only supported for simple type keys, i.e. each index name must point to a string representation of a simple open type. As many path elements must be provided as index names for the tabular type exists (i.e. pExtraArgs.size() >= pValue.getTabularType().getIndexNames().size()) For TabularData representing maps, a path access with the single "key" value will return the content of the "value" value. For all other TabularData, the complete row to which the path points is returned.

Specified by:

extractObject in interface Extractor

Parameters:

pConverter - the global converter in order to be able do dispatch for serializing inner data types

pValue - the value to convert

pPathParts - extra arguments which contain e.g. a path

pJsonify - whether to convert to a JSON object/list or whether the plain object should be returned. The later is required for writing an inner value

Returns:

the extracted object

Throws:

AttributeNotFoundException

setObjectValue

public Object setObjectValue(StringToObjectConverter pConverter,
                    Object pInner,
                    String pAttribute,
                    Object pValue)
                      throws IllegalAccessException,
                             InvocationTargetException

Throws always IllegalArgumentException since tabular data is immutable

Specified by:

setObjectValue in interface Extractor

Parameters:

pConverter - the global converter in order to be able do dispatch for serializing inner data types

pInner - object on which to set the value

pAttribute - attribute of the object to set

pValue - the new value to set

Returns:

the old value

Throws:

IllegalAccessException - if the attribute to set to is not accessible

InvocationTargetException - reflection error

canSetValue

public boolean canSetValue()

Whether this extractor is able to set a value.

Specified by:

canSetValue in interface Extractor

Returns:

true if this extractor can set a value, false otherwise.