edu.wpi.cs.wpisuitetng.modules.core.models.UserDeserializer.java Source code

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/*******************************************************************************
 * Copyright (c) 2012 -- WPI Suite
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    twack
 *******************************************************************************/

package edu.wpi.cs.wpisuitetng.modules.core.models;

import java.lang.reflect.Type;
import java.util.Map.Entry;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.Set;

import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;

/**
 * A custom deserializer class for the GSON JSON library.
 *    The password field should not be exposed after inflation, so it is set to null.
 * @author twack
 *
 */
public class UserDeserializer implements JsonDeserializer<User> {

    private static final Logger logger = Logger.getLogger(UserDeserializer.class.getName());

    @Override
    public User deserialize(JsonElement userElement, Type userType, JsonDeserializationContext context)
            throws JsonParseException {
        JsonObject deflated = userElement.getAsJsonObject();

        if (!deflated.has("username")) {
            throw new JsonParseException("The serialized User did not contain the required username field.");
        }

        // for all other attributes: instantiate as null, fill in if given.

        int idNum = 0;
        String username = deflated.get("username").getAsString();
        String name = null;
        String password = null;

        if (deflated.has("idNum") && !deflated.get("idNum").getAsString().equals("")) {
            try {
                idNum = deflated.get("idNum").getAsInt();
            } catch (java.lang.NumberFormatException e) {
                logger.log(Level.FINER, "User transmitted with String in iDnum field");
            }
        }

        if (deflated.has("password") && !deflated.get("password").getAsString().equals("")) {
            password = deflated.get("password").getAsString();
        }

        if (deflated.has("name") && !deflated.get("name").getAsString().equals("")) {
            name = deflated.get("name").getAsString();
        }

        User inflated = new User(name, username, password, idNum);

        if (deflated.has("role") && !deflated.get("role").getAsString().equals("")) {
            Role r = Role.valueOf(deflated.get("role").getAsString());
            inflated.setRole(r);
        }

        return inflated;
    }

    /**
     * This static utility method takes a JSON string and attempts to
     *    retrieve a password field from it.
     * @param serializedUser   a JSON string containing a password
     * @return   the password field parsed.
     */
    public static String parsePassword(String serializedUser) {
        if (!serializedUser.contains("password")) {
            throw new JsonParseException("The given JSON string did not contain a password field.");
        }

        int fieldStartIndex = serializedUser.indexOf("password");
        int separator = serializedUser.indexOf(':', fieldStartIndex);
        int startIndex = serializedUser.indexOf('"', separator) + 1;
        int endIndex = serializedUser.indexOf('"', startIndex);

        String password = serializedUser.substring(startIndex, endIndex);

        return password;
    }

}