Java tutorial
/** * ClarescoExperienceAPI * Copyright * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General protected License version 2 only, as * published by the Free Software Foundation. * * Please contact Claresco, www.claresco.com, if you have any questions. **/ package com.claresco.tinman.json; import java.lang.reflect.Type; import java.util.ArrayList; import java.util.Map; import com.claresco.tinman.lrs.XapiAccount; import com.claresco.tinman.lrs.XapiActivity; import com.claresco.tinman.lrs.XapiActivityDefinition; import com.claresco.tinman.lrs.XapiActor; import com.claresco.tinman.lrs.XapiAgent; import com.claresco.tinman.lrs.XapiContext; import com.claresco.tinman.lrs.XapiContextActivities; import com.claresco.tinman.lrs.XapiExtension; import com.claresco.tinman.lrs.XapiGroup; import com.claresco.tinman.lrs.XapiIRI; import com.claresco.tinman.lrs.XapiInteraction; import com.claresco.tinman.lrs.XapiInteractionComponent; import com.claresco.tinman.lrs.XapiInverseFunctionalIdentifier; import com.claresco.tinman.lrs.XapiLanguageMap; import com.claresco.tinman.lrs.XapiObject; import com.claresco.tinman.lrs.XapiPerson; import com.claresco.tinman.lrs.XapiResult; import com.claresco.tinman.lrs.XapiScore; import com.claresco.tinman.lrs.XapiStatement; import com.claresco.tinman.lrs.XapiStatementBatch; import com.claresco.tinman.lrs.XapiStatementRef; import com.claresco.tinman.lrs.XapiStatementResult; import com.claresco.tinman.lrs.XapiSubStatement; import com.claresco.tinman.lrs.XapiVerb; import com.claresco.tinman.servlet.XapiCredentials; import com.claresco.tinman.servlet.XapiCredentialsList; import com.google.gson.Gson; import com.google.gson.GsonBuilder; import com.google.gson.JsonArray; import com.google.gson.JsonDeserializationContext; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import com.google.gson.JsonSerializationContext; /** * JsonUtility.java * * Description: * Collection of useful methods for Json related purposes * * Status: * GREEN * * @author rheza * on Feb 25, 2014 * */ public final class JsonUtility { /** * * Description: * Building Gson * * Params: * */ public static Gson createGson() { final GsonBuilder gsonBuilder = new GsonBuilder(); //Register to gsonBuilder gsonBuilder.registerTypeAdapter(XapiStatement.class, new XapiStatementJson()); gsonBuilder.registerTypeAdapter(XapiActor.class, new XapiActorJson()); gsonBuilder.registerTypeAdapter(XapiAgent.class, new XapiAgentJson()); gsonBuilder.registerTypeAdapter(XapiGroup.class, new XapiGroupJson()); gsonBuilder.registerTypeAdapter(XapiInverseFunctionalIdentifier.class, new XapiInverseFuncIdJson()); gsonBuilder.registerTypeAdapter(XapiAccount.class, new XapiAccountJson()); gsonBuilder.registerTypeAdapter(XapiVerb.class, new XapiVerbJson()); gsonBuilder.registerTypeAdapter(XapiObject.class, new XapiObjectJson()); gsonBuilder.registerTypeAdapter(XapiStatementRef.class, new XapiStatementRefJson()); gsonBuilder.registerTypeAdapter(XapiSubStatement.class, new XapiSubStatementJson()); gsonBuilder.registerTypeAdapter(XapiActivity.class, new XapiActivityJson()); gsonBuilder.registerTypeAdapter(XapiActivityDefinition.class, new XapiActivityDefinitionJson()); gsonBuilder.registerTypeAdapter(XapiLanguageMap.class, new XapiLanguageMapJson()); gsonBuilder.registerTypeAdapter(XapiResult.class, new XapiResultJson()); gsonBuilder.registerTypeAdapter(XapiScore.class, new XapiScoreJson()); gsonBuilder.registerTypeAdapter(XapiContextActivities.class, new XapiContextActivitiesJson()); gsonBuilder.registerTypeAdapter(XapiContext.class, new XapiContextJson()); gsonBuilder.registerTypeAdapter(XapiInteraction.class, new XapiInteractionJson()); gsonBuilder.registerTypeAdapter(XapiInteractionComponent.class, new XapiInteractionComponentJson()); gsonBuilder.registerTypeAdapter(XapiCredentials.class, new XapiCredentialsJson()); gsonBuilder.registerTypeAdapter(XapiStatementBatch.class, new XapiStatementBatchJson()); gsonBuilder.registerTypeAdapter(XapiPerson.class, new XapiPersonJson()); gsonBuilder.registerTypeAdapter(XapiStatementResult.class, new XapiStatementResultJson()); gsonBuilder.registerTypeAdapter(XapiExtension.class, new XapiExtensionsJson()); gsonBuilder.registerTypeAdapter(XapiCredentialsList.class, new XapiCredentialsListJson()); final Gson gson = gsonBuilder.create(); return gson; } /** * Description: * Convert JsonElement to JsonObject, i.e. Mapping * Params: * */ protected static JsonObject convertJsonElementToJsonObject(JsonElement element) { if (element == null) { throw new XapiBadJsonObjectException("element is null"); } if (isNotJsonObject(element)) { throw new XapiBadJsonObjectException(element.getAsString() + " is not an object"); } return element.getAsJsonObject(); } /** * Description: * Based on the mapping, find the element I want * Remember that JsonObject is collection of element mapped by its key * * Params: * */ protected static JsonElement findJsonElementWithKey(JsonObject theObject, String key) { return theObject.get(key); } /** * Description: * Check if the element equals certain string * * Params: * */ protected static Boolean elementEqualString(JsonElement theElement, String theString) { return theElement.getAsString().equals(theString); } /** * Description: * Let some piece of element to be deserialized by another class * * Params: * */ protected static <T> T delegateDeserialization(JsonDeserializationContext theContext, JsonElement theElement, Type theType) { return theContext.deserialize(theElement, theType); } /** * Description: * Get the piece of the whole statement as a String * * Params: * */ protected static String getElementAsString(JsonObject theObject, String theKey) { if (hasElement(theObject, theKey)) { return theObject.get(theKey).getAsString(); } else { return null; } } protected static Integer getElementAsInt(JsonObject theObject, String theKey) { if (hasElement(theObject, theKey)) { return theObject.get(theKey).getAsInt(); } else { return null; } } protected static Double getElementAsDouble(JsonObject theObject, String theKey) { if (hasElement(theObject, theKey)) { return theObject.get(theKey).getAsDouble(); } else { return null; } } protected static Boolean getElementAsBool(JsonObject theObject, String theKey) { if (hasElement(theObject, theKey)) { return theObject.get(theKey).getAsBoolean(); } else { return null; } } protected static boolean isJsonElementNull(JsonElement theElement) { return theElement.isJsonNull(); } protected static boolean hasElement(JsonObject theObject, String theKey) { if (theObject.has(theKey)) { if (!isJsonElementNull(get(theObject, theKey))) { return true; } } return false; } protected static boolean isActivityOfTypeInteraction(String theType) { return theType.equals("http://adlnet.gov/expapi/activities/cmi.interaction"); } protected static JsonArray getAnArray(JsonObject theObject, String theKey) { if (hasElement(theObject, theKey)) { return theObject.get(theKey).getAsJsonArray(); } else { return null; } } protected static JsonElement get(JsonObject theObject, String theKey) { return theObject.get(theKey); } /** * * Description: * Handling interaction * * Params: * */ protected static ArrayList<XapiInteractionComponent> handleInteraction(JsonObject theObject, String theKey, JsonDeserializationContext theContext) { if (hasElement(theObject, theKey)) { JsonArray theJsonArray = getAnArray(theObject, theKey); ArrayList<XapiInteractionComponent> theArray = new ArrayList<XapiInteractionComponent>(); // Convert Json Array into array of XapiInteractionComponent for (JsonElement element : theJsonArray) { theArray.add((XapiInteractionComponent) JsonUtility.delegateDeserialization(theContext, element, XapiInteractionComponent.class)); } return theArray; } return null; } /** * * Description: * Create a JsonArray from XapiInteractionComponents * * Params: * */ protected static JsonArray jsonArrayFromXapiInteractionComponent( ArrayList<XapiInteractionComponent> theComponents, JsonSerializationContext theContext) { JsonArray theArray = new JsonArray(); for (XapiInteractionComponent component : theComponents) { theArray.add(theContext.serialize(component)); } return theArray; } protected static XapiLanguageMap constructLanguageMap(JsonObject theObject, String key) { XapiLanguageMap theLanguageMap = new XapiLanguageMap(); if (theObject.get(key) == null) { return null; } for (Map.Entry<String, JsonElement> entry : theObject.get(key).getAsJsonObject().entrySet()) { theLanguageMap.registerLanguage(entry.getKey(), entry.getValue().getAsString()); } return theLanguageMap; } protected static ArrayList<XapiActivity> convertJsonArrayOfActivities(JsonObject theObject, String theElementName, ArrayList<XapiActivity> theArrayList, JsonDeserializationContext theContext) { JsonElement theActivities; if (hasElement(theObject, theElementName)) { theActivities = get(theObject, theElementName); if (theActivities.isJsonArray()) { JsonArray theJsonArray = getAnArray(theObject, theElementName); for (JsonElement e : theJsonArray) { theArrayList.add((XapiActivity) delegateDeserialization(theContext, e, XapiActivity.class)); } } else { theArrayList .add((XapiActivity) delegateDeserialization(theContext, theActivities, XapiActivity.class)); } } return theArrayList; } protected static JsonArray convertToJsonArray(ArrayList<String> theList) { JsonArray theArray = new JsonArray(); for (String s : theList) { theArray.add(new JsonPrimitive(s)); } return theArray; } protected static JsonArray convertToJsonArrayFromIRIList(ArrayList<XapiIRI> theList) { ArrayList<String> theStringList = new ArrayList<String>(); for (XapiIRI theIRI : theList) { theStringList.add(theIRI.toString()); } return convertToJsonArray(theStringList); } protected static boolean isJsonObject(JsonElement theElement) { return theElement.isJsonObject(); } protected static boolean isNotJsonObject(JsonElement theElement) { return !isJsonObject(theElement); } }