Hi,
As the initial step, we had to read data from JSON and CSV using selectors.
Selector format was decided to be the following.
> employee.firstname
> customers.customer.account.number
Following libraries were used to read data by converting the selector to
jsonpath and CSV header.
*Axiom* to read XML
*Jayway jsonpath*
elementPath = "$.." + elementPath;
nodesList = new ArrayList<Object>();
nodesList = JsonPath.read(jsonString, elementPath); //elementPath-jsonpath
*Javacsv 2.0*
csvReader = new CsvReader(inputFile.getCanonicalPath());
csvReader.readHeaders();
inputValueList = new ArrayList<Object>();
while(csvReader.readRecord()){
inputValueList.add(csvReader.get(elementPath)); //elementPath-CSV header
}
In an intermediate step, processed data is stored in a hashmap and
therefore I had to write data from the hashmap to different data types
(XML, JSON, CSV). Following is what I have tried.
*DOM* as a solution to create output XML.
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
doc = docBuilder.newDocument();
Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
int i=0;
while (iterator.hasNext()) {
Map.Entry<String,String> pairs = (Map.Entry<String,String>)iterator.next();
//Set root node
if(i==0){
Element rootElement =
doc.createElement(pairs.getKey().toString().split("\\.")[0]);
doc.appendChild(rootElement);
mappedNodes.put(pairs.getKey().toString().split("\\.")[0], rootElement);
}
chooseNode(pairs.getKey().toString(), pairs.getValue().toString());
i++;
}
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(file);
transformer.transform(source, result);
*Google Gson* as a JSON builder.
baseNode = new HashMap<String, Object>();
List<Map<String, Object>> firstNode = new ArrayList<Map<String, Object>>();
baseNode.put(key.substring(0, key.indexOf(".")), firstNode); //first node
if(getNode instanceof List)
((List<List<Map<String, Object>>>) getNode).add(list);
else if(getNode instanceof Map)
((Map<String, Object>) getNode).put(lastNode,
(value.equals(""))?list:value);
Gson gson = new GsonBuilder().setPrettyPrinting().create();
String jsonString = gson.toJson(baseNode);
*Open-csv *CsvWriter to write CSV with header.
writer = new CSVWriter(new FileWriter(file));
Set<String> keySet = map.keySet();
List<String> keyList = new ArrayList<String>();
keyList.addAll(keySet);
//Csv header
List<String> csvHeader = new ArrayList<String>();
Iterator<String> it = keySet.iterator();
while ( it.hasNext() ){
csvHeader.add(it.next());
}
writer.writeNext(csvHeader.toArray(new String[csvHeader.size()]));
//Csv data
List<String[]> csvData = new ArrayList<String[]>();
for(int i=0; i < map.get( keySet.iterator().next() ).size() ; i++){
String[] stringArray = new String[keyList.size()];
//iterate over keyList
for(int j=0; j<keyList.size(); j++){
stringArray[j] = map.get(keyList.get(j)).get(i);
}
csvData.add(stringArray);
}
writer.writeAll(csvData);
writer.close();
WDYT? Are there any better ways to do this?
--
*Gayan Kaushalya Yalpathwala*
Software Engineer
WSO2 Inc.; http://wso2.com
lean.enterprise.middleware
mobile: +94 71 8682704
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