HTML Parser

Primarily used for transformation or extraction, it features filters, custom tags, visitors, and easy to use JavaBeans. HTML Parser is a robust, fast, and well tested package.

HTML Parser is a useful Java library designed for HTML transformation or extraction.

The two fundamental use-cases that are handled by the parser are extraction and transformation (the syntheses use-case, where HTML pages are created from scratch, is better handled by other tools closer to the source of data).

In general, to use the HTMLParser you will need to be able to write code in the Java programming language. Although some example programs are provided that may be useful as they stand, it's more than likely you will need (or want) to create your own programs or modify the ones provided to match your intended application.

To use the library, you will need to add either the htmllexer.jar or htmlparser.jar to your classpath when compiling and running. The htmllexer.jar provides low level access to generic string, remark and tag nodes on the page in a linear, flat, sequential manner.

The htmlparser.jar, which includes the classes found in htmllexer.jar, provides access to a page as a sequence of nested differentiated tags containing string, remark and other tag nodes.

Extraction encompasses all the information retrieval programs that are not meant to preserve the source page.

This covers uses like: · text extraction, for use as input for text search engine databases for example · link extraction, for crawling through web pages or harvesting email addresses · screen scraping, for programmatic data input from web pages · resource extraction, collecting images or sound · a browser front end, the preliminary stage of page display · link checking, ensuring links are valid · site monitoring, checking for page differences beyond simplistic diffs

There are several facilities in the HTMLParser codebase to help with extraction, including filters, visitors and JavaBeans.

Transformation includes all processing where the input and the output are HTML pages.

Some examples are: · URL rewriting, modifying some or all links on a page · site capture, moving content from the web to local disk · censorship, removing offending words and phrases from pages · HTML cleanup, correcting erroneous pages · ad removal, excising URLs referencing advertising · conversion to XML, moving existing web pages to XML

During or after reading in a page, operations on the nodes can accomplish many transformation tasks "in place", which can then be output with the toHtml() method. Depending on the purpose of your application, you will probably want to look into node decorators, visitors, or custom tags in conjunction with the PrototypicalNodeFactory.