package.html
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> 2 <html> 3 <head> 4 <!-- 5 HTMLParser Library $Name: v1_6_20060319 $ - A java-based parser for HTML 6 http://sourceforge.org/projects/htmlparser 7 Copyright (C) 2004 Somik Raha 8 9 Revision Control Information 10 11 $Source: /cvsroot/htmlparser/htmlparser/src/org/htmlparser/tags/package.html,v $ 12 $Author: derrickoswald $ 13 $Date: 2005/04/24 17:48:27 $ 14 $Revision: 1.21 $ 15 16 This library is free software; you can redistribute it and/or 17 modify it under the terms of the GNU Lesser General Public 18 License as published by the Free Software Foundation; either 19 version 2.1 of the License, or (at your option) any later version. 20 21 This library is distributed in the hope that it will be useful, 22 but WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 Lesser General Public License for more details. 25 26 You should have received a copy of the GNU Lesser General Public 27 License along with this library; if not, write to the Free Software 28 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 29 --> 30 </head> 31 <body bgcolor="white"> 32 The tags package contains specific tags. 33 <p>This package has implementations of tags that have functionality beyond the 34 capability of a generic tag. For example, the {@.html <META>} tag has methods 35 to get the {@link org.htmlparser.tags.MetaTag#getMetaContent CONTENT} and 36 {@link org.htmlparser.tags.MetaTag#getMetaTagName NAME} 37 attributes (although this could be done with generic attribute manipulation) 38 and an implementation of 39 {@link org.htmlparser.tags.MetaTag#doSemanticAction doSemanticAction} 40 that alters the lexer's encoding.</p> 41 <p>The classes in this package have been added in an ad-hoc fashion, with the 42 most useful ones having existed a long time, while some obvious ones are rather 43 new. Please feel free to add your own custom tags, and register them with the 44 {@link org.htmlparser.PrototypicalNodeFactory PrototypicalNodeFactory}, 45 and they will be treated like any other in-built tag. In fact tags do not need 46 to reside in this package.</p> 47 <br><b>Custom Tags</b> 48 <p>Creating custom tags is fairly straight forward. Simply copy one of the 49 simpler tags you find in this package and alter it as follows. 50 <p>If the tag can contain other nodes, i.e. {@.html <h1>My Heading</h1>}, then 51 it should derive from (i.e. be a subclass of) {@link org.htmlparser.tags.CompositeTag}. 52 In this way it will inherit the 53 {@link org.htmlparser.scanners.CompositeTagScanner CompositeTagScanner} 54 and nodes between the start and end tag will be gathered into the list of 55 children. Most of the tags in this package derive from CompositeTag, and that 56 is why the nodes returned from the Parser are nested.</p> 57 <p>If it is a simple tag, i.e. {@.html <br>}, then it should derive from 58 {@link org.htmlparser.nodes.TagNode TagNode}. See for example 59 {@link org.htmlparser.tags.MetaTag} 60 or {@link org.htmlparser.tags.ImageTag}.</p> 61 <p>To be registered with {@link org.htmlparser.PrototypicalNodeFactory#registerTag}, 62 and especially if it is a composite tag, the tag needs to implement 63 <code>getIds</code> which returns the UPPERCASE list of names for the tag 64 (usually only one), for example "HTML". If the tag can be smart enough to know 65 what other tags can't be contained within it, it should also implement 66 {@link org.htmlparser.nodes.TagNode#getEnders getEnders()} which returns the 67 list of other tags that should cause this tag to close itself, and 68 {@link org.htmlparser.nodes.TagNode#getEndTagEnders getEndTagEnders()} which 69 returns the list of end tags (i.e. {@.html </xxx>}), other than it's own name, that 70 should cause this tag to close itself. When these 'ender' lists cause a tag to 71 end before seeing it's own end tag, a virtual end tag is created and 'inserted' 72 at the location where the end tag should have been. These end tags can be 73 distinguished because their {@link org.htmlparser.Node#getStartPosition starting} 74 and {@link org.htmlparser.Node#getEndPosition ending} locations are the same 75 (i.e. they take up no character length in the HTML stream). 76 <p>For example, the {@.html <OPTION>} tag from a form can be prematurely ended by 77 any of {@.html <INPUT>}, {@.html <TEXTAREA>}, {@.html <SELECT>}, 78 or another {@.html <OPTION>} tag. These are the tags in the getEnders() list. 79 It can also be prematurely ended by {@.html </SELECT>}, {@.html </FORM>}, 80 {@.html </BODY>}, or {@.html </HTML>}. These are the tags in the 81 getEndTagEnders() list. 82 <p>Other than that any functionality is up to you. You should note that 83 {@link org.htmlparser.Node#doSemanticAction doSemanticAction()} is called after 84 the tag has been completely scanned (it has it's children and end tag), but before 85 its siblings further downstream have been scanned. If transformation is your purpose, 86 this is the opportunity to mess around with the content, for example to set the link URL, 87 or lowercase the tag name, or whatever. 88 <!-- Put @see and @since tags down here. --> 89 90 </body> 91 </html>