root/trunk/LogicMail/src/org/logicprobe/LogicMail/util/UtilProxy.java

/*-
 * Copyright (c) 2006, Derek Konigsberg
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution. 
 * 3. Neither the name of the project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.logicprobe.LogicMail.util;

import java.io.IOException;

/**
 * Proxy for utility classes and methods that may
 * have multiple implementations depending on the
 * project build configuration.
 */
public abstract class UtilProxy {
    private static UtilProxy instance = null;
    
    /**
     * Get a class reference for the util proxy, using exception catching
     * to determine which one this build has been compiled with.
     */
    private static Class getUtilProxyClass() {
        Class utilProxyClass;
        try {
            utilProxyClass = Class.forName("org.logicprobe.LogicMail.util.UtilProxyBB41");
            return utilProxyClass;
        }
        catch (ClassNotFoundException e) { }
        try {
            utilProxyClass = Class.forName("org.logicprobe.LogicMail.util.UtilProxyBB40");
            return utilProxyClass;
        }
        catch (ClassNotFoundException e) { }
        return null;
    }
    
    /**
     * Creates a new instance of UtilProxy
     */
    private static UtilProxy createUtilProxy() {
        UtilProxy utilProxy = null;
        Class utilProxyClass = getUtilProxyClass();
        if(utilProxyClass == null) {
            return null;
        }

        try {
            utilProxy = (UtilProxy)utilProxyClass.newInstance();
        } catch (InstantiationException e) {
            utilProxy = null;
        } catch (IllegalAccessException e) {
            utilProxy = null;
        }
        return utilProxy;
    }

    public static synchronized UtilProxy getInstance() {
        if(instance == null) {
            instance = createUtilProxy();
            if(instance == null) {
                throw new RuntimeException("Application configuration error");
            }
        }
        
        return instance;
    }
    
    /**
     * Decode the Base64 encoded input and return the result.
     *
     * @param input The Base64 encoded input
     * @return A byte array containing the decoded input.
     * @throws IOException Thrown if a decoding error occurred.
     */
    public abstract byte[] Base64Decode(String input) throws IOException;
    
    /**
     * Encodes the provided input into Base 64 and returns the encoded result.
     *
     * @param input       The input data to encode
     * @param inputOffset The offset into the array
     * @param inputLength The length of the array
     * @param insertCR    Set to true if you want to insert a CR after every 76th encoded character
     * @param insertLF    Set to true if you want to insert a LF after every 76th encoded character
     * @throws IOException Thrown if an encoding error occurred
     * @return The encoded input as a byte array
     */
    public abstract byte[] Base64Encode(byte[] input, int inputOffset, int inputLength, boolean insertCR, boolean insertLF) throws IOException;
    
    /**
     * Encodes the provided input into Base 64 and returns the encoded result.
     *
     * @param input       The input data to encode
     * @param inputOffset The offset into the array
     * @param inputLength The length of the array
     * @param insertCR    Set to true if you want to insert a CR after every 76th encoded character
     * @param insertLF    Set to true if you want to insert a LF after every 76th encoded character
     * @throws IOException Thrown if an encoding error occurred
     * @return The encoded input as a string
     */
    public abstract String Base64EncodeAsString(byte[] input, int inputOffset, int inputLength, boolean insertCR, boolean insertLF) throws IOException;
}