/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.vfs2.util;

Factory to create an instance of a Cryptor.
Since:
2.0/**
 * Factory to create an instance of a Cryptor.
 *
 * @since 2.0
 */
public final class CryptorFactory {

    
The System property name to identify the Cryptor class to be used.
/**
     * The System property name to identify the Cryptor class to be used.
     */
    public static final String CRYPTOR_CLASS = "org.apache.commons.vfs2.cryptor";

    private static Cryptor instance;

    
Prevent instantiation of the class.
/**
     * Prevent instantiation of the class.
     */
    private CryptorFactory() {

    }

    
Allows the Cryptor class to be set programmatically.
Params:
cryptor – The Cryptor./**
     * Allows the Cryptor class to be set programmatically.
     *
     * @param cryptor The Cryptor.
     */
    public static synchronized void setCryptor(final Cryptor cryptor) {
        instance = cryptor;
    }

    
Return the Cryptor. If one has not been previously set, create it. The Cryptor class can be set by setting the
"org.apache.commons.vfs2.cryptor" System property to the name of the Cryptor class.
Returns:
The Cryptor./**
     * Return the Cryptor. If one has not been previously set, create it. The Cryptor class can be set by setting the
     * "org.apache.commons.vfs2.cryptor" System property to the name of the Cryptor class.
     *
     * @return The Cryptor.
     */
    public static synchronized Cryptor getCryptor() {
        if (instance != null) {
            return instance;
        }

        final String cryptorClass = System.getProperty(CRYPTOR_CLASS);
        if (cryptorClass != null) {
            try {
                final Class<?> clazz = Class.forName(cryptorClass);
                instance = (Cryptor) clazz.newInstance();
                return instance;
            } catch (final Exception ex) {
                throw new RuntimeException("Unable to create Cryptor " + cryptorClass, ex);
            }
        }
        instance = new DefaultCryptor();
        return instance;
    }
}