org.codelibs.fess.crawler.helper.RobotsTxtHelper.java Source code

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Here is the source code for org.codelibs.fess.crawler.helper.RobotsTxtHelper.java

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/*
 * Copyright 2012-2016 CodeLibs Project and the Others.
 *
 * 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 org.codelibs.fess.crawler.helper;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.io.input.BOMInputStream;
import org.codelibs.core.lang.StringUtil;
import org.codelibs.fess.crawler.Constants;
import org.codelibs.fess.crawler.entity.RobotsTxt;
import org.codelibs.fess.crawler.entity.RobotsTxt.Directive;
import org.codelibs.fess.crawler.exception.RobotsTxtException;

/**
 * Robots.txt Specifications:
 * <ul>
 * <li><a href=
 * "https://developers.google.com/webmasters/control-crawl-index/docs/robots_txt"
 * >https://developers.google.com/webmasters/control-crawl-index/docs/robots_txt
 * </a></li>
 * </ul>
 *
 * @author bowez
 * @author shinsuke
 *
 */
public class RobotsTxtHelper {

    protected static final Pattern USER_AGENT_RECORD = Pattern
            .compile("^user-agent:\\s*([^\\t\\n\\x0B\\f\\r]+)\\s*$", Pattern.CASE_INSENSITIVE);

    protected static final Pattern DISALLOW_RECORD = Pattern.compile("^disallow:\\s*([^\\s]*)\\s*$",
            Pattern.CASE_INSENSITIVE);

    protected static final Pattern ALLOW_RECORD = Pattern.compile("^allow:\\s*([^\\s]*)\\s*$",
            Pattern.CASE_INSENSITIVE);

    protected static final Pattern CRAWL_DELAY_RECORD = Pattern.compile("^crawl-delay:\\s*([^\\s]+)\\s*$",
            Pattern.CASE_INSENSITIVE);

    protected static final Pattern SITEMAP_RECORD = Pattern.compile("^sitemap:\\s*([^\\s]+)\\s*$",
            Pattern.CASE_INSENSITIVE);

    protected boolean enabled = true;

    public RobotsTxt parse(final InputStream stream) {
        return parse(stream, Constants.UTF_8);
    }

    public RobotsTxt parse(final InputStream stream, final String charsetName) {
        if (!enabled) {
            return null;
        }

        try {
            @SuppressWarnings("resource")
            final BufferedReader reader = new BufferedReader(
                    new InputStreamReader(new BOMInputStream(stream), charsetName));

            String line;
            final RobotsTxt robotsTxt = new RobotsTxt();
            final List<Directive> currentDirectiveList = new ArrayList<Directive>();
            boolean isGroupRecodeStarted = false;
            while ((line = reader.readLine()) != null) {
                line = stripComment(line).trim();
                if (StringUtil.isEmpty(line)) {
                    continue;
                }

                String value;
                if ((value = getValue(USER_AGENT_RECORD, line)) != null) {
                    if (isGroupRecodeStarted) {
                        currentDirectiveList.clear();
                        isGroupRecodeStarted = false;
                    }
                    final String userAgent = value.toLowerCase(Locale.ENGLISH);
                    Directive currentDirective = robotsTxt.getDirective(userAgent);
                    if (currentDirective == null) {
                        currentDirective = new Directive(userAgent);
                        robotsTxt.addDirective(currentDirective);
                        currentDirectiveList.add(currentDirective);
                    }
                } else {
                    isGroupRecodeStarted = true;
                    if ((value = getValue(DISALLOW_RECORD, line)) != null) {
                        if (!currentDirectiveList.isEmpty() && value.length() > 0) {
                            for (final Directive directive : currentDirectiveList) {
                                directive.addDisallow(value);
                            }
                        }
                    } else if ((value = getValue(ALLOW_RECORD, line)) != null) {
                        if (!currentDirectiveList.isEmpty() && value.length() > 0) {
                            for (final Directive directive : currentDirectiveList) {
                                directive.addAllow(value);
                            }
                        }
                    } else if ((value = getValue(CRAWL_DELAY_RECORD, line)) != null) {
                        if (!currentDirectiveList.isEmpty()) {
                            try {
                                final int crawlDelay = Integer.parseInt(value);
                                for (final Directive directive : currentDirectiveList) {
                                    directive.setCrawlDelay(Math.max(0, crawlDelay));
                                }
                            } catch (final NumberFormatException e) {
                                // ignore
                            }
                        }
                    } else if ((value = getValue(SITEMAP_RECORD, line)) != null) {
                        if (value.length() > 0) {
                            robotsTxt.addSitemap(value);
                        }
                    }
                }
            }

            return robotsTxt;
        } catch (final Exception e) {
            throw new RobotsTxtException("Failed to parse robots.txt.", e);
        }
    }

    protected String getValue(final Pattern pattern, final String line) {
        final Matcher m = pattern.matcher(line);
        if (m.matches() && m.groupCount() > 0) {
            return m.group(1);
        }
        return null;
    }

    protected String stripComment(final String line) {
        final int commentIndex = line.indexOf('#');
        if (commentIndex != -1) {
            return line.substring(0, commentIndex);
        }
        return line;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(final boolean enabled) {
        this.enabled = enabled;
    }

}