Java tutorial
/******************************************************************************* * Copyright 2013 Open mHealth * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. ******************************************************************************/ package org.openmhealth.reference.request; import java.io.IOException; import java.util.ArrayList; import java.util.List; import org.openmhealth.reference.data.DataSet; import org.openmhealth.reference.data.Registry; import org.openmhealth.reference.domain.AuthenticationToken; import org.openmhealth.reference.domain.Data; import org.openmhealth.reference.domain.MetaData; import org.openmhealth.reference.domain.MultiValueResult; import org.openmhealth.reference.domain.Schema; import org.openmhealth.reference.domain.User; import org.openmhealth.reference.exception.InvalidAuthenticationException; import org.openmhealth.reference.exception.OmhException; import com.fasterxml.jackson.core.JsonFactory; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.MappingJsonFactory; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ArrayNode; import com.fasterxml.jackson.databind.node.ObjectNode; /** * <p> * Stores the given data. * </p> * * @author John Jenkins */ public class DataWriteRequest extends Request<Object> { /** * The JSON factory that is used to create the parser that will be used to * parse the data. */ private static final JsonFactory JSON_FACTORY = new MappingJsonFactory(); /** * The authentication token for the requesting user. */ private final AuthenticationToken authToken; /** * The ID of the schema from which the data was generated. */ private final String schemaId; /** * The version of the schema from which the data was generated. */ private final long version; /** * The data to validate and store. */ private final String data; /** * Creates a request to store some data. * * @param authToken * The requesting user's authentication token. * * @param schemaId * The ID of the schema which should be used to validate the data. * * @param version * The version of the schema which should be used to validate the * data. * * @param data * The data to validate and store. * * @throws OmhException * A parameter was invalid. */ public DataWriteRequest(final AuthenticationToken authToken, final String schemaId, final long version, final String data) throws OmhException { if (authToken == null) { throw new InvalidAuthenticationException("The authentication token is missing."); } if (schemaId == null) { throw new OmhException("The schema ID is missing."); } if (data == null) { throw new OmhException("The data is missing."); } this.authToken = authToken; this.schemaId = schemaId; this.version = version; this.data = data; } /** * Validates the data and, if valid, stores it. */ @Override public void service() throws OmhException { // First, short-circuit if this request has already been serviced. if (isServiced()) { return; } else { setServiced(); } // Check to be sure the schema is known. MultiValueResult<? extends Schema> schemas = Registry.getInstance().getSchemas(schemaId, version, 0, 1); if (schemas.count() == 0) { throw new OmhException( "The schema ID, '" + schemaId + "', and version, '" + version + "', pair is unknown."); } Schema schema = schemas.iterator().next(); // Get the user that owns this token. User requestingUser = authToken.getUser(); // Parse the data. JsonNode dataNode; try { dataNode = JSON_FACTORY.createJsonParser(data).readValueAs(JsonNode.class); } catch (JsonParseException e) { throw new OmhException("The data was not well-formed JSON.", e); } catch (JsonProcessingException e) { throw new OmhException("The data was not well-formed JSON.", e); } catch (IOException e) { throw new OmhException("The data could not be read.", e); } // Make sure it is a JSON array. if (!(dataNode instanceof ArrayNode)) { throw new OmhException("The data was not a JSON array."); } ArrayNode dataArray = (ArrayNode) dataNode; // Get the number of data points. int numDataPoints = dataArray.size(); // Create the result list of data points. List<Data> dataPoints = new ArrayList<Data>(numDataPoints); // Create a new ObjectMapper that will be used to convert the meta-data // node into a MetaData object. ObjectMapper mapper = new ObjectMapper(); // For each element in the array, be sure it is a JSON object that // represents a valid data point for this schema. for (int i = 0; i < numDataPoints; i++) { // Get the current data point. JsonNode dataPoint = dataArray.get(i); // Validate that it is a JSON object. if (!(dataPoint instanceof ObjectNode)) { throw new OmhException("A data point was not a JSON object: " + i); } ObjectNode dataObject = (ObjectNode) dataPoint; // Attempt to get the meta-data; MetaData metaData = null; JsonNode metaDataNode = dataObject.get(Data.JSON_KEY_METADATA); if (metaDataNode != null) { metaData = mapper.convertValue(metaDataNode, MetaData.class); } // Attempt to get the schema data. JsonNode schemaData = dataObject.get(Data.JSON_KEY_DATA); // If the data is missing, fail the request. if (schemaData == null) { throw new OmhException("A data point's '" + Data.JSON_KEY_DATA + "' field is missing."); } // Create and add the point to the set of data. dataPoints.add(schema.validateData(requestingUser.getUsername(), metaData, schemaData)); } // Store the data. DataSet.getInstance().storeData(dataPoints); } }