FacebookJSONParser.java

/*
 * Copyright 2012 Feedlr
 *
 * 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 com.chalmers.feedlr.parser;

import java.io.IOException;
import java.util.List;

import com.chalmers.feedlr.model.FacebookItem;
import com.chalmers.feedlr.model.User;
import com.fasterxml.jackson.core.JsonParseException;

import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectReader;

import android.util.Log;

/**
 * Class description
 * 
 * @author Daniel Larsson
 * 
 *         A parser for Facebook responses. The parsing is done with the Jackson
 *         JSON Processor.
 */

public class FacebookJSONParser {

	private static ObjectMapper mapper;
	private static ObjectReader itemReader;
	private static ObjectReader userReader;

	public FacebookJSONParser() {
		if (mapper == null) {
			mapper = new ObjectMapper();
			mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,
					false);
		}
	}

	/*
	 * Parse a JSON response for a list of statuses from Facebook's REST API
	 * with Jackson's databinding parse method.
	 * 
	 * @return list containing <code>FacebookItems</code>
	 */
	public List<FacebookItem> parseFeed(String json) {
		long time = System.currentTimeMillis();

		if (itemReader == null) {
			itemReader = mapper.reader(new TypeReference<List<FacebookItem>>() {
			});
		}

		List<FacebookItem> list = null;

		if (json.contains("statuses")) {
			String data = json.substring(json.indexOf("statuses") + 18);
			try {
				list = itemReader.readValue(data);
				Log.i(FacebookJSONParser.class.getName(),
						"Parsed " + list.size() + " Facebook items in "
								+ (System.currentTimeMillis() - time)
								+ " millis.");
			} catch (JsonParseException e) {
				Log.e(getClass().getName(), e.getMessage());
			} catch (JsonMappingException e) {
				Log.e(getClass().getName(), e.getMessage());
			} catch (IOException e) {
				Log.e(getClass().getName(), e.getMessage());
			}
		}

		return list;
	}

	/*
	 * Parse a JSON response for a list of users from Facebook's REST API with
	 * Jackson's databinding parse method. The list will be filled with
	 * 
	 * @return list containing <code>Users</code>
	 */
	public List<User> parseUsers(String json) {
		long time = System.currentTimeMillis();
		String data = json.substring(8);

		if (userReader == null) {
			userReader = mapper.reader(new TypeReference<List<User>>() {
			});
		}
		List<User> list = null;

		try {
			list = userReader.readValue(data);
		} catch (JsonParseException e) {
			Log.e(getClass().getName(), e.getMessage());
		} catch (JsonMappingException e) {
			Log.e(getClass().getName(), e.getMessage());
		} catch (IOException e) {
			Log.e(getClass().getName(), e.getMessage());
		}

		Log.i(FacebookJSONParser.class.getName(), "Parsed " + list.size()
				+ " Facebook users in " + (System.currentTimeMillis() - time)
				+ " millis.");

		return list;
	}
}