Parse an InputStream for multiple patterns

Question

I am parsing an InputStream for certain patterns to extract values from it, e.g. I would have something like

<span class="filename"><a href="http://example.com/foo">foo</a>

I don't want to use a full fledged html parser as I am not interested in the document structure but only in some well defined bits of information. (Only their order is important)
Currently I am using a very simple approach, I have an Object for each Pattern that contains a char[] of the opening and closing 'tag' (in the example opening would be <span class="filename"><a href="and closing " to get the url) and a position marker. For each character read by of the InputStream, I iterate over all Patterns and call the match(char) function that returns true once the opening pattern does match, from then on I collect the following chars in a StringBuilder until the now active pattern does match() again. I then call a function with the ID of the Pattern and the String read, to process it further.
While this works fine in most cases, I wanted to include regular expressions in the pattern, so I could also match something like

<span class="filename" id="234217"><a href="http://example.com/foo">foo</a>

At this point I was sure I would reinvent the wheel as this most certainly would have been done before, and I don't really want to write my own regex parser to begin with. However, I could not find anything that would do what I was looking for.
Unfortunately the Scanner class only matches one pattern, not a list of patterns, what alternatives could I use? It should not be heavy and work with Android.

Answer 1

You mean you want to match any <span> element with a given class attribute, irrespective of other attributes it may have? That's easy enough:

Scanner sc = new Scanner(new File("test.txt"), "UTF-8");
Pattern p = Pattern.compile(
    "<span[^>]*class=\"filename\"[^>]*>\\s*<a[^>]*href=\"([^\"]+)\""
);
while (sc.findWithinHorizon(p, 0) != null)
{
  MatchResult m = sc.match();
  System.out.println(m.group(1));
}

The file "test.txt" contains the text of your question, and the output is:

http://example.com/foo
and closing
http://example.com/foo