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/**
* Copyright (c) 2011, 2013, Jonathan Giles, Johan Vos, Hendrik Ebbers
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of DataFX, the website javafxdata.org, nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.datafx.reader.converter;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.map.MappingJsonFactory;
import org.codehaus.jackson.map.ObjectMapper;
import org.datafx.provider.ObjectDataProvider;
/**
*
* An implementation of {@link Converter} that converts JSON data into Java Objects
* of type T.
*
* @Param the type of the resulting Java objects
* @author johan
*/
public class JsonConverter extends InputStreamConverter {
private JsonNode rootNode;
private final String tag;
private final Class clazz;
Iterator iterator;
private static final Logger LOGGER = Logger.getLogger(JsonConverter.class.getName());
/**
* Create a JsonConverter that will generate instances of the specified class.
* @param clazz the entities returned by the {@link get()} call will be of class clazz
*/
public JsonConverter (Class clazz) {
this (null, clazz);
}
/**
* Create a JsonConverter that will generate instances of the specified class.
* Using this constructor, it is assumed that the entities are contained within a
* Json structure in a Node with the name specified by the value of the tag parameter.
* @param clazz the entities returned by the {@link get()} call will be of class clazz
* @param tag the name of the json node(s) holding the data entity(ies).
*/
public JsonConverter(String tag, Class clazz) {
this.tag = tag;
this.clazz = clazz;
}
@Override
public void initialize(InputStream input) {
try {
MappingJsonFactory mappingJsonFactory = new MappingJsonFactory();
JsonParser jp = mappingJsonFactory.createJsonParser(input);
rootNode = jp.readValueAsTree();
if (tag != null) {
JsonNode cNode = rootNode.findValue(tag);
if (cNode != null) {
iterator = cNode.iterator();
}
else {
System.err.println("Couldn't find a rootnode for tag "+tag+", rootNode = "+rootNode);
// we were looking for a tag, but couldn't find one.
// TODO: does this mean we should throw an exception, or will we use the children on the root node instead?
}
}
} catch (IOException ex) {
// TODO throw an exception? fatal?
Logger.getLogger(JsonConverter.class.getName()).log(Level.SEVERE, null, ex);
}
}
@Override
public T get() { // if no tag is specified, we assume it is a single item
LOGGER.log(Level.FINER, "getting json data, tag = {0}", tag);
if (tag == null) {
try {
ObjectMapper om = new ObjectMapper();
Object o = om.readValue(rootNode, clazz);
LOGGER.finer("did read Object "+o);
final T entry = (T) o;
return entry;
} catch (IOException ex) {
Logger.getLogger(JsonConverter.class.getName()).log(Level.SEVERE, null, ex);
}
} else {
try {
// this will fail if the iterator is null, which happens if we don't find the tag in the nodelist
JsonNode candidate = iterator.next();
ObjectMapper om = new ObjectMapper();
final T entry = (T) om.readValue(candidate, clazz);
return entry;
} catch (IOException ex) {
Logger.getLogger(JsonConverter.class.getName()).log(Level.SEVERE, null, ex);
}
}
// TODO rather throw an exception
return null;
}
@Override
public boolean next() {
if (tag == null) {
return false;
} else {
return iterator.hasNext();
}
}
}
