Java tutorial
/* * This software is released under the GNU Lesser General Public License v3. * For more information see http://www.gnu.org/licenses/lgpl.html * * Copyright (c) 2011, Peter Knego & Matjaz Tercelj * All rights reserved. */ package com.leanengine; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.util.*; /** * Internal utility class for decoding REST messages. */ public class JsonDecode { static LeanAccount accountFromJson(JSONObject json) throws LeanException { Long id; try { id = json.getLong("id"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field 'id'."); } String providerId; try { providerId = json.getString("providerId"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field 'providerId'."); } String nickName; try { nickName = json.getString("nickName"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field 'nickName'."); } String provider; try { provider = json.getString("provider"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field 'provider'."); } JSONObject jsonProviderProperties; Map<String, Object> providerProperties; try { jsonProviderProperties = json.getJSONObject("providerProperties"); providerProperties = accountPropsFromJson(jsonProviderProperties); return new LeanAccount(id, nickName, providerId, provider, providerProperties); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field 'providerProperties'."); } } private static Map<String, Object> accountPropsFromJson(JSONObject jsonNode) throws LeanException, JSONException { Map<String, Object> props = new HashMap<String, Object>(jsonNode.length()); // must have some properties if (jsonNode.length() == 0) throw new LeanException(LeanError.Type.ServerError, "Malformed reply: JSON parameter 'providerProperties' must not be empty."); Iterator fieldNames = jsonNode.keys(); while (fieldNames.hasNext()) { String field = (String) fieldNames.next(); props.put(field, jsonNode.get(field)); } return props; } static LeanEntity[] entityListFromJson(JSONObject json) throws LeanException { try { JSONArray array = json.getJSONArray("result"); LeanEntity[] result = new LeanEntity[array.length()]; for (int i = 0; i < array.length(); i++) { JSONObject item = array.getJSONObject(i); result[i] = entityFromJson(item); } return result; } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: " + e); } } static LeanEntity entityFromJson(JSONObject json) throws LeanException { String kind; try { kind = json.getString("_kind"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field '_kind'."); } Long id; try { id = json.getLong("_id"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field '_id'."); } Long accountId; try { accountId = json.getLong("_account"); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Entity JSON missing field '_account'."); } LeanEntity entity = new LeanEntity(kind, id, accountId); try { entity.properties = entityPropertiesFromJson(json); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: " + e); } return entity; } static Map<String, Object> entityPropertiesFromJson(JSONObject jsonNode) throws LeanException, JSONException { Map<String, Object> props = new HashMap<String, Object>(jsonNode.length()); // must have some properties if (jsonNode.length() == 0) throw new LeanException(LeanError.Type.ServerError, "Empty reply."); Iterator fieldNames = jsonNode.keys(); while (fieldNames.hasNext()) { String field = (String) fieldNames.next(); // skip LeanEngine system properties (starting with underscore '_') if (field.startsWith("_")) continue; Object subNode = jsonNode.get(field); props.put(field, propertyFromJson(subNode)); } return props; } static Object propertyFromJson(Object jsonNode) throws LeanException, JSONException { if (jsonNode instanceof JSONObject) { return typedObjectFromJson((JSONObject) jsonNode); } else if (jsonNode instanceof JSONArray) { return typedArrayFromJson((JSONArray) jsonNode); } return jsonNode; } private static List<Object> typedArrayFromJson(JSONArray arrayNode) throws LeanException, JSONException { List<Object> result = new ArrayList<Object>(arrayNode.length()); for (int i = 0; i < arrayNode.length(); i++) { Object node = arrayNode.getJSONObject(i); if (node instanceof JSONObject) { result.add(typedObjectFromJson((JSONObject) node)); } else { result.add(node); } } return result; } private static Object typedObjectFromJson(JSONObject node) throws LeanException, JSONException { // must have 'type' field String type = node.getString("type"); if (type == null) throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Missing 'type' field."); if ("date".equals(type)) { return new Date(getLongFromValueNode("value", node)); } else if ("text".equals(type)) { return new LeanText(getStringFromValueNode("value", node)); } else if ("geopt".equals(type)) { throw new IllegalArgumentException("Value nodes of type 'geopt' are not yet implemented."); } else if ("geohash".equals(type)) { throw new IllegalArgumentException("Value nodes of type 'geohash' are not yet implemented."); } else if ("blob".equals(type)) { throw new IllegalArgumentException("Value nodes of type 'blob' are not yet implemented."); } else if ("shortblob".equals(type)) { throw new IllegalArgumentException("Value nodes of type 'shortblob' are not yet implemented."); } else if ("reference".equals(type)) { throw new IllegalArgumentException("Value nodes of type 'reference' are not yet implemented."); } else { //unknown node type throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Unknown type '" + type + "'."); } } private static long getLongFromValueNode(String fieldName, JSONObject node) throws LeanException { try { return node.getLong(fieldName); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Missing '" + fieldName + "' field."); } } private static String getStringFromValueNode(String fieldName, JSONObject node) throws LeanException { try { return node.getString(fieldName); } catch (JSONException e) { throw new LeanException(LeanError.Type.ServerError, "Malformed reply: Missing '" + fieldName + "' field."); } } }