URLHandlerRegistry.java

/*
 *  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.ivy.util.url;

import org.apache.ivy.util.Message;

/**
 *
 */
public final class URLHandlerRegistry {
    private URLHandlerRegistry() {
    }

    private static URLHandler defaultHandler = new BasicURLHandler();

    public static URLHandler getDefault() {
        return defaultHandler;
    }

    public static void setDefault(URLHandler def) {
        defaultHandler = def;
    }

    /**
     * This method is used to get appropriate http downloader dependening on Jakarta Commons
     * HttpClient availability in classpath, or simply use jdk url handling in other cases.
     * 
     * @return most accurate http downloader
     */
    public static URLHandler getHttp() {
        try {
            Class.forName("org.apache.commons.httpclient.HttpClient");

            // temporary fix for IVY-880: only use HttpClientHandler when
            // http-client-3.x is available
            Class.forName("org.apache.commons.httpclient.params.HttpClientParams");

            Class handler = Class.forName("org.apache.ivy.util.url.HttpClientHandler");
            Message.verbose("jakarta commons httpclient detected: using it for http downloading");
            return (URLHandler) handler.newInstance();
        } catch (ClassNotFoundException e) {
            Message.verbose("jakarta commons httpclient not found: using jdk url handling");
            return new BasicURLHandler();
        } catch (NoClassDefFoundError e) {
            Message.verbose("error occurred while loading jakarta commons httpclient: "
                    + e.getMessage());
            Message.verbose("Using jdk url handling instead.");
            return new BasicURLHandler();
        } catch (InstantiationException e) {
            Message.verbose("couldn't instantiate HttpClientHandler: using jdk url handling");
            return new BasicURLHandler();
        } catch (IllegalAccessException e) {
            Message.verbose("couldn't instantiate HttpClientHandler: using jdk url handling");
            return new BasicURLHandler();
        }
    }

}