course.SessionDAO.java Source code

Introduction

Here is the source code for course.SessionDAO.java

Source

/*
 * Copyright (c) 2008 - 2013 10gen, Inc. <http://10gen.com>
 * 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 course;

import java.security.SecureRandom;

import org.apache.commons.codec.binary.Base64;

import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBObject;

public class SessionDAO {

    private final DBCollection sessionsCollection;

    public SessionDAO(final DB blogDatabase) {
        sessionsCollection = blogDatabase.getCollection("sessions");
    }

    public String findUserNameBySessionId(String sessionId) {
        DBObject session = getSession(sessionId);

        if (session == null) {
            return null;
        } else {
            return session.get("username").toString();
        }
    }

    // starts a new session in the sessions table
    public String startSession(String username) {

        // get 32 byte random number. that's a lot of bits.
        SecureRandom generator = new SecureRandom();
        byte randomBytes[] = new byte[32];
        generator.nextBytes(randomBytes);

        // result = new Base64().encodeToString(rawHmac);

        // BASE64Encoder encoder = new BASE64Encoder();

        // String sessionID = encoder.encode(randomBytes);

        String sessionID = new Base64().encodeToString(randomBytes);

        // build the BSON object
        BasicDBObject session = new BasicDBObject("username", username);

        session.append("_id", sessionID);

        sessionsCollection.insert(session);

        return session.getString("_id");
    }

    // ends the session by deleting it from the sesisons table
    public void endSession(String sessionID) {
        sessionsCollection.remove(new BasicDBObject("_id", sessionID));
    }

    // retrieves the session from the sessions table
    public DBObject getSession(String sessionID) {
        return sessionsCollection.findOne(new BasicDBObject("_id", sessionID));
    }
}