com.code.savemarks.utils.Utils.java Source code

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Here is the source code for com.code.savemarks.utils.Utils.java

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/** 
 * Copyright 2010 Daniel Guermeur and Amy Unruh
 *
 *   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.
 *
 *   See http://connectrapp.appspot.com/ for a demo, and links to more information 
 *   about this app and the book that it accompanies.
 */
package com.code.savemarks.utils;

/**
 * Some code adapted from: the Google App Engine Virtual File System (GaeVFS) project,
 * http://code.google.com/p/gaevfs/
 */

import static org.apache.commons.codec.binary.Base64.decodeBase64;
import static org.apache.commons.codec.binary.Base64.encodeBase64;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.servlet.http.HttpServletRequest;

import com.google.appengine.api.labs.taskqueue.QueueFailureException;

public class Utils {

    private static final Logger log = Logger.getLogger(Utils.class.getName());

    /**
     * Serialize an object into a byte array.
     * 
     * @param obj An object to be serialized.
     * @return A byte array containing the serialized object
     * @throws QueueFailureException If an I/O error occurs during the
     * serialization process.
     */
    public static byte[] serialize(Object obj) {
        try {
            ByteArrayOutputStream bytesOut = new ByteArrayOutputStream();
            ObjectOutputStream objectOut = new ObjectOutputStream(new BufferedOutputStream(bytesOut));
            objectOut.writeObject(obj);
            objectOut.close();
            return encodeBase64(bytesOut.toByteArray());
        } catch (IOException e) {
            throw new QueueFailureException(e);
        }
    }

    /**
     * Deserialize an object from an HttpServletRequest input stream. Does not
     * throw any exceptions; instead, exceptions are logged and null is returned.
     * 
     * @param req An HttpServletRequest that contains a serialized object.
     * @return An object instance, or null if an exception occurred.
     */
    public static Object deserialize(HttpServletRequest req) {
        if (req.getContentLength() == 0) {
            log.severe("request content length is 0");
            return null;
        }
        try {
            byte[] bytesIn = new byte[req.getContentLength()];
            req.getInputStream().readLine(bytesIn, 0, bytesIn.length);
            return deserialize(bytesIn);
        } catch (IOException e) {
            log.log(Level.SEVERE, "Error deserializing task", e);
            return null; // don't retry task
        }
    }

    /**
     * Deserialize an object from a byte array. Does not throw any exceptions;
     * instead, exceptions are logged and null is returned.
     * 
     * @param bytesIn A byte array containing a previously serialized object.
     * @return An object instance, or null if an exception occurred.
     */
    public static Object deserialize(byte[] bytesIn) {
        ObjectInputStream objectIn = null;
        try {
            bytesIn = decodeBase64(bytesIn);
            objectIn = new ObjectInputStream(new BufferedInputStream(new ByteArrayInputStream(bytesIn)));
            return objectIn.readObject();
        } catch (Exception e) {
            log.log(Level.SEVERE, "Error deserializing task", e);
            return null; // don't retry task
        } finally {
            try {
                if (objectIn != null) {
                    objectIn.close();
                }
            } catch (IOException ignore) {
            }
        }
    }

    public static String stackTraceToString(Throwable e) {
        String retValue = null;
        StringWriter sw = null;
        PrintWriter pw = null;
        try {
            sw = new StringWriter();
            pw = new PrintWriter(sw);
            e.printStackTrace(pw);
            retValue = sw.toString();
        } finally {
            try {
                if (pw != null)
                    pw.close();
                if (sw != null)
                    sw.close();
            } catch (IOException ignore) {
            }
        }
        return retValue;
    }

} // end class