hasattributefilter.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) 2003 Derrick Oswald
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/filters/HasAttributeFilter.java,v $
// $Author: derrickoswald $
// $Date: 2005/05/15 11:49:04 $
// $Revision: 1.7 $
//
// 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.filters;

import java.util.Locale;

import org.htmlparser.Attribute;
import org.htmlparser.Node;
import org.htmlparser.NodeFilter;
import org.htmlparser.Tag;

/**
 * This class accepts all tags that have a certain attribute,
 * and optionally, with a certain value.
 */
public class HasAttributeFilter implements NodeFilter
{
    /**
     * The attribute to check for.
     */
    protected String mAttribute;

    /**
     * The value to check for.
     */
    protected String mValue;

    /**
     * Creates a new instance of HasAttributeFilter.
     * With no attribute name, this would always return <code>false</code>
     * from {@link #accept}.
     */
    public HasAttributeFilter ()
    {
        this ("", null);
    }

    /**
     * Creates a new instance of HasAttributeFilter that accepts tags
     * with the given attribute.
     * @param attribute The attribute to search for.
     */
    public HasAttributeFilter (String attribute)
    {
        this (attribute, null);
    }

    /**
     * Creates a new instance of HasAttributeFilter that accepts tags
     * with the given attribute and value.
     * @param attribute The attribute to search for.
     * @param value The value that must be matched,
     * or null if any value will match.
     */
    public HasAttributeFilter (String attribute, String value)
    {
        mAttribute = attribute.toUpperCase (Locale.ENGLISH);
        mValue = value;
    }

    /**
     * Get the attribute name.
     * @return Returns the name of the attribute that is acceptable.
     */
    public String getAttributeName ()
    {
        return (mAttribute);
    }

    /**
     * Set the attribute name.
     * @param name The name of the attribute to accept.
     */
    public void setAttributeName (String name)
    {
        mAttribute = name;
    }

    /**
     * Get the attribute value.
     * @return Returns the value of the attribute that is acceptable.
     */
    public String getAttributeValue ()
    {
        return (mValue);
    }

    /**
     * Set the attribute value.
     * @param value The value of the attribute to accept.
     * If <code>null</code>, any tag with the attribute,
     * no matter what it's value is acceptable.
     */
    public void setAttributeValue (String value)
    {
        mValue = value;
    }

    /**
     * Accept tags with a certain attribute.
     * @param node The node to check.
     * @return <code>true</code> if the node has the attribute
     * (and value if that is being checked too), <code>false</code> otherwise.
     */
    public boolean accept (Node node)
    {
        Tag tag;
        Attribute attribute;
        boolean ret;

        ret = false;
        if (node instanceof Tag)
        {
            tag = (Tag)node;
            attribute = tag.getAttributeEx (mAttribute);
            ret = null != attribute;
            if (ret && (null != mValue))
                ret = mValue.equals (attribute.getValue ());
        }

        return (ret);
    }
}