filter.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) 2005 Derrick Oswald
//
// Revision Control Information
//
// $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/parserapplications/filterbuilder/Filter.java,v $
// $Author: derrickoswald $
// $Date: 2005/04/12 11:27:42 $
// $Revision: 1.2 $
//
// 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.parserapplications.filterbuilder;

import java.awt.*;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.Hashtable;
import java.util.Vector;

import javax.swing.*;
import javax.swing.border.*;

import org.htmlparser.NodeFilter;
import org.htmlparser.Parser;
import org.htmlparser.parserapplications.filterbuilder.layouts.VerticalLayoutManager;

/**
 * Base class for all filters.
 * Provides common functionality applicable to all filters.
 */
public abstract class Filter
    extends
        JComponent
    implements
        NodeFilter
{
    /**
     * Create a new filter from the class name.
     * @param class_name The class to instatiate.
     * @return The constructed filter object.
     */
    public static Filter instantiate (String class_name)
    {
        Filter ret;
        
        ret = null;
        try
        {
            Class cls = Class.forName (class_name);
            ret = (Filter)cls.newInstance ();
            mWrappers.put (ret.getNodeFilter ().getClass ().getName (), class_name);
        }
        catch (ClassNotFoundException cnfe)
        {
            System.out.println ("can't find class " + class_name);
        }
        catch (InstantiationException ie)
        {
            System.out.println ("can't instantiate class " + class_name);
        }
        catch (IllegalAccessException ie)
        {
            System.out.println ("class " + class_name + " has no public constructor");
        }
        catch (ClassCastException cce)
        {
            System.out.println ("class " + class_name + " is not a Filter");
        }
        
        return (ret);
    }

    /**
     * Map from cilter class to wrapper.
     * Populated as part of each wrapper being loaded.
     */
    protected static Hashtable mWrappers = new Hashtable ();

    /**
     * Create a filter.
     * Set up the default display.
     * Only a border with the label of the filter name,
     * returned by <code>getDescription()</code>,
     * and an icon, returned by <code>getIcon()</code>.
     */
    public Filter ()
    {
        JLabel label;
        Dimension dimension;
        Insets insets;

        setToolTipText (getDescription ());
        // none of these quite does it:
        // new BoxLayout (this, BoxLayout.Y_AXIS));
        // new GridLayout (0, 1));
        setLayout (new VerticalLayoutManager ());
        setSelected (false);
        label = new JLabel (getDescription (), getIcon (), SwingConstants.LEFT);
        label.setBackground (Color.green);
        label.setAlignmentX (Component.LEFT_ALIGNMENT);
        label.setHorizontalAlignment (SwingConstants.LEFT);
        add (label);
        dimension = label.getMaximumSize ();
        insets = getInsets ();
        dimension.setSize (dimension.width + insets.left + insets.right, dimension.height + insets.top + insets.bottom);
        setSize (dimension);
    }

    /**
     * Get the name of the filter.
     * @return A descriptive name for the filter.
     */
    public abstract String getDescription ();

    /**
     * Get the underlying node filter object.
     * @return The node filter object suitable for serialization.
     */
    public abstract NodeFilter getNodeFilter ();

    /**
     * Assign the underlying node filter for this wrapper.
     * @param filter The filter to wrap.
     * @param context The parser to use for conditioning this filter.
     * Some filters need contextual information to provide to the user,
     * i.e. for tag names or attribute names or values,
     * so the Parser context is provided. 
     */
    public abstract void setNodeFilter (NodeFilter filter, Parser context);

    /**
     * Get the underlying node filter's subordinate filters.
     * @return The node filter object's contained filters.
     */
    public abstract NodeFilter[] getSubNodeFilters ();

    /**
     * Assign the underlying node filter's subordinate filters.
     * @param filters The filters to insert into the underlying node filter.
     */
    public abstract void setSubNodeFilters (NodeFilter[] filters);

    /**
     * Convert this filter into Java code.
     * Output whatever text necessary and return the variable name.
     * @param out The output buffer.
     * @param context Three integers as follows:
     * <li>indent level - the number of spaces to insert at the beginning of each line</li>
     * <li>filter number - the next available filter number</li>
     * <li>filter array number - the next available array of filters number</li>
     * @return The variable name to use when referencing this filter (usually "filter" + context[1]++) 
     */
    public abstract String toJavaCode (StringBuffer out, int[] context);

    /**
     * Get the icon for the filter.
     * Loads the resource specified by 
     * <code>getIconSpec()</code> as an icon.
     * @return The icon or null if it was not found.
     */
    public Icon getIcon ()
    {
        ImageIcon ret;
        
        ret = null;
        try
        {
            ret = new ImageIcon (getClass ().getResource (getIconSpec ()));
        }
        catch (NullPointerException npe)
        {
            System.err.println ("can't find icon " + getIconSpec ());
        }
        
        return (ret);
    }
    
    /**
     * Get the resource name for the icon.
     * @return The icon resource specification.
     */
    public abstract String getIconSpec ();

    //
    // Component overrides
    //

    /**
     * Returns a string representation of this component and its values.
     * @return A string representation of this component.
     */
    public String toString ()
    {
        return (getDescription () + " [" + this.getClass ().getName () + "]");
    }

    //
    // utilities
    //

    /**
     * Serialize an object to a byte array.
     * @param object The object to be pickled.
     * @return The serialized object.
     * @exception IOException If the output stream complains (unlikely).
     */
    public static byte[] pickle (Object object)
        throws
            IOException
    {
        ByteArrayOutputStream bos;
        ObjectOutputStream oos;
        byte[] ret;

        bos = new ByteArrayOutputStream ();
        oos = new ObjectOutputStream (bos);
        oos.writeObject (object);
        oos.close ();
        ret = bos.toByteArray ();

        return (ret);
    }

    /**
     * Reconstitute a serialized object.
     * @param data The pickled object.
     * @return The reconstituted object.
     * @exception IOException If the input stream complains. 
     * @exception ClassNotFoundException If the serialized object class cannot
     * be located.
     */
    public static Object unpickle (byte[] data)
        throws
            IOException,
            ClassNotFoundException
    {
        ByteArrayInputStream bis;
        ObjectInputStream ois;