ar.com.zauber.commons.web.proxy.impl.RegexURLRequestMapper.java Source code

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Here is the source code for ar.com.zauber.commons.web.proxy.impl.RegexURLRequestMapper.java

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/**
 * Copyright (c) 2005-2012 Zauber S.A. <http://www.zaubersoftware.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 ar.com.zauber.commons.web.proxy.impl;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.lang.UnhandledException;
import org.apache.commons.lang.Validate;

import ar.com.zauber.commons.web.proxy.URLRequestMapper;
import ar.com.zauber.commons.web.proxy.URLResult;

/**
 * Regex URL Mapper. Use regular expressions to extract information
 * from the request URI and build the URL.
 * For example:
 * <ul> 
 *    <li>base url mapper: <tt>http://localhost:9095</tt>
 *    <li>regular expresion: ^/([^/]+)/([^/]+)/([^/]+)/(.*)$</li>
 *    <li>replace pattern: ^$1-$2-$3/$4$</li>
 * </ul> 
 * A request to <tt>/zauber/code/releases/foo/bar.pom</tt> would generate
 * the URL 
 *    <tt>http://localhost:9095/zauber-code-releases/foo/bar.pom</tt>
 * @author Juan F. Codagnone
 * @since Aug 28, 2008
 */
public class RegexURLRequestMapper extends AbstractURLRequestMapper {
    private final URLRequestMapper base;
    private final Pattern regex;
    private final String replacePattern;

    /** 
     * Creates the RegexURLRequestMapper.
     *
     * @param base   delegating  URLRequestMapper for the first part of the url
     * @param regex  Regular expresion to match. Use groups.
     * @param replacePattern  replace pattern.
     */
    public RegexURLRequestMapper(final URLRequestMapper base, final Pattern regex, final String replacePattern) {
        Validate.notNull(base);
        Validate.notNull(regex);
        Validate.notNull(replacePattern);

        this.base = base;
        this.regex = regex;
        this.replacePattern = replacePattern;
    }

    /** 
     * Creates the RegexURLRequestMapper.
     *
     * @param regex  Regular expresion to match. Use groups.
     * @param replacePattern  the result must be an URL
     */
    public RegexURLRequestMapper(final Pattern regex, final String replacePattern) {
        Validate.notNull(regex);
        Validate.notNull(replacePattern);

        this.base = null;
        this.regex = regex;
        this.replacePattern = replacePattern;
    }

    /** @see URLRequestMapper#getProxiedURLFromRequest(HttpServletRequest) */
    public final URLResult getProxiedURLFromRequest(final HttpServletRequest request) {
        final Matcher m = regex.matcher(getRequestURI(request));
        final URLResult ret;

        if (m.matches()) {
            final String uri = m.replaceAll(replacePattern);
            try {
                if (base == null) {
                    ret = new InmutableURLResult(new URL(uri));
                } else {
                    final URLResult r = base.getProxiedURLFromRequest(request);
                    if (r.hasResult()) {
                        ret = new InmutableURLResult(new URL(r.getURL().toExternalForm() + uri));
                    } else {
                        ret = r;
                    }
                }
            } catch (final MalformedURLException e) {
                throw new UnhandledException(e);
            }
        } else {
            ret = new InmutableURLResult();
        }

        return ret;
    }

    /** @see java.lang.Object#toString() */
    @Override
    public final String toString() {
        final String ret;
        if (base == null) {
            ret = regex.toString() + "=" + replacePattern;
        } else {
            ret = super.toString();
        }
        return ret;
    }

    public final String getReplacePattern() {
        return replacePattern;
    }

    public final Pattern getRegex() {
        return regex;
    }
}