linkprocessor.java

本程序用于对页面信息进行提取并分析

// HTMLParser Library $Name: v1_6_20060319 $ - A java-based parser for HTML
// http://sourceforge.org/projects/htmlparser
// Copyright (C) 2004 Somik Raha
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/util/LinkProcessor.java,v $
// $Author: derrickoswald $
// $Date: 2004/07/31 16:42:34 $
// $Revision: 1.35 $
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//

package org.htmlparser.util;

import java.io.Serializable;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Processor class for links, is present basically as a utility class.
 * @deprecated Use a Page object instead.
 */
public class LinkProcessor
    implements
        Serializable
{
    /**
     * Overriding base URL.
     * If set, this is used instead of a provided base URL in extract().
     */
    private String baseUrl;

    /**
     * Create an HTMLLinkProcessor.
     */
    public LinkProcessor ()
    {
        baseUrl = null;
    }

    /**
     * Create an absolute URL from a possibly relative link and a base URL.
     * @param link The reslative portion of a URL.
     * @param base The base URL unless overridden by the current baseURL property.
     * @return The fully qualified URL or the original link if a failure occured.
     * @deprecated Use Page.getAbsoluteURL() instead.
     */
    public String extract (String link, String base)
    {
        String ret;

        try
        {
            if (null == link)
                link = "";
            else
                link = stripQuotes (link);
            if (null != getBaseUrl ())
                base = getBaseUrl ();
            if ((null == base) || ("".equals (link)))
                ret = link;
            else
            {
                URL url = constructUrl(link, base);
                ret = url.toExternalForm ();
            }
        }
        catch (MalformedURLException murle)
        {
            ret = link;
        }

        return (Translate.decode (ret));
    }

    /**
     * Remove double or single quotes from the string.
     */
    public String stripQuotes (String string)
    {
        // remove any double quotes from around string
        if (string.startsWith ("\"") && string.endsWith ("\"") && (1 < string.length ()))
            string = string.substring (1, string.length () - 1);

        // remove any single quote from around string
        if (string.startsWith ("'") && string.endsWith ("'") && (1 < string.length ()))
            string = string.substring (1, string.length () - 1);

        return (string);
    }

    /**
     * @deprecated Use Page.constructUrl() instead.
     */
    public URL constructUrl(String link, String base)
        throws MalformedURLException {
        String path;
        boolean modified;
        boolean absolute;
        int index;
        URL url; // constructed URL combining relative link and base
        url = new URL (new URL (base), link);
        path = url.getFile ();
        modified = false;
        absolute = link.startsWith ("/");
        if (!absolute) {   // we prefer to fix incorrect relative links
            // this doesn't fix them all, just the ones at the start
            while (path.startsWith ("/.")) {
                if (path.startsWith ("/../")) {
                    path = path.substring (3);
                    modified = true;
                }
                else if (path.startsWith ("/./") || path.startsWith("/.")) {
                    path = path.substring (2);
                    modified = true;
                } else break;
            }
        }
        // fix backslashes
        while (-1 != (index = path.indexOf ("/\\"))) {
            path = path.substring (0, index + 1) + path.substring (index + 2);
            modified = true;
        }
        if (modified)
            url = new URL (url, path);
        return url;
    }

    /**
     * Turn spaces into %20.
     * @param url The url containing spaces.
     * @return The URL with spaces as %20 sequences.
     * @deprecated Use Parser.fixSpaces() instead.
     */
    public static String fixSpaces (String url)
    {
        int index;
        int length;
        char ch;
        StringBuffer returnURL;

        index = url.indexOf (' ');
        if (-1 != index)
        {
            length = url.length ();
            returnURL = new StringBuffer (length * 3);
            returnURL.append (url.substring (0, index));
            for (int i = index; i < length; i++)
            {
                ch = url.charAt (i);
                if (ch==' ')
                    returnURL.append ("%20");
                else
                    returnURL.append (ch);
            }
            url = returnURL.toString ();
        }

        return (url);
    }

    /**
     * Check if a resource is a valid URL.
     * @param resourceLocn The resource to test.
     * @return <code>true</code> if the resource is a valid URL.
     */
    public static boolean isURL (String resourceLocn) {
        boolean ret;

        try
        {
            new URL (resourceLocn);
            ret = true;
        }
        catch (MalformedURLException murle)
        {
            ret = false;
        }

        return (ret);
    }

    /**
     * Returns the baseUrl.
     * @return String
     */
    public String getBaseUrl ()
    {
        return baseUrl;
    }

    /**
     * Sets the baseUrl.
     * @param baseUrl The baseUrl to set
     */
    public void setBaseUrl (String baseUrl)
    {
        this.baseUrl = baseUrl;
    }

    /**
     * @deprecated Removing the last slash from a URL is a bad idea.
     */
    public static String removeLastSlash(String baseUrl) {
      if(baseUrl.charAt(baseUrl.length()-1)=='/')
      {
         return baseUrl.substring(0,baseUrl.length()-1);
      }
      else
      {
         return baseUrl;
      }
    }

}