http://www.coderanch.com/t/620233/Web-Services/java/Expression-based-Json-Query-Engine

gistfile1.txt

import java.util.ArrayList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONObject;

public class JsonQueryEngine {
                
                public static List<String> getExpressionValues(String expression, String propertySeperator, JSONObject jsonObject) throws Exception{
                                String[] nodesList = expression.split(propertySeperator);//Splitting each property in expression
                                List<String> expressionValues = new ArrayList<String>();
                                List<JSONObject> jsonObjects = new ArrayList<JSONObject>();
                                //Temporary Objects for swapping (Won't consume much memory as the values are pointers)
                                List<JSONObject> intermediateJsonObjects = new ArrayList<JSONObject>();
                                
                                jsonObjects.add(jsonObject);
                                //Populating targeted Json
                                for (int i = 0; i < nodesList.length - 1; i++) {
                                                for (JSONObject propertyObject : jsonObjects) {
                                                                intermediateJsonObjects.addAll(getNodeJsonObjects(nodesList[i], propertyObject));
                                                }
                                                jsonObjects.clear();
                                                jsonObjects.addAll(intermediateJsonObjects);
                                                intermediateJsonObjects.clear();
                                }
                                //Populating targeted Json Values
                                for (JSONObject propertyObject : jsonObjects) {
                                                expressionValues.add(propertyObject.get(nodesList[nodesList.length - 1]).toString());
                                }
                                
                                return expressionValues;
                }

                private static List<JSONObject> getNodeJsonObjects(String node, JSONObject parentObject) throws Exception{
                                List<JSONObject> nodeJsonObjects = new ArrayList<JSONObject>();
                                Object object = parentObject.get(node);
                                if(object instanceof JSONObject)
                                                nodeJsonObjects.add((JSONObject)object);
                                else{
                                                JSONArray jsonArray = (JSONArray)object;
                                                for (int i = 0; i < jsonArray.length(); i++) {
                                                                nodeJsonObjects.add((JSONObject)jsonArray.get(i));
                                                }
                                }
                                return nodeJsonObjects;
                }
}