RTF Parser Kit
I have often been frustrated by the lack of comprehensive support for working with RTF in Java, and the need to use RTF parsers which are incomplete and form part of larger projects whose libraries I don't want to import just to use the RTF parser. The RTF Parser Kit project is an attempt to address these points.
The idea is to provide a "kit" of components which can either be used "as-is", for example to extract plain text or HTML from an RTF file, or can be used as a component in a larger application which requires the capability to parse RTF documents.
What's currently included?
- Raw RTF Parser - parses RTF, sends events representing content to a listener. Performs minimal processing - you get the RTF commands and data exactly as they appear in the file.
- Standard RTF Parser - parses RTF, sends events representing content to a listener. Handles character encoding, Unicode and so on, so you don't have to. This is probably the parser you want to use.
- Text Converter - demonstrates very simple text extraction from an RTF file
- RTF Dump - another demonstration, this time writing the RTF file contents as XML
You have a choice of two parsers to work with, the standard parser and the raw parser. The raw parser carries out minimal processing on the RTF, the standard parser handles character encodings, and translates commands which represent special characters into their Unicode equivalents. Most people will want to use the standard parser.
The parser is invoked like this:
InputStream is = new FileInputStream("/path/to/my/file.rtf"); IRtfSource source = new RtfStreamSource(is) IRtfParser parser = new StandardRtfParser(); MyRtfListener listener = new MyRtfListener(); parser.parse(source, listener);
You provide input to the parser via a class that implements the
IRtfSource interface. Two implementations are provided for you,
RtfStreamSource, for reading RTF from a stream, and
RtfStringSource for reading RTF from a string.
The other thing you need to provide the parser with is a listener class. The listener class implements the
IRtfListener listener interface. The interface consists of a set of methods which are called by the parser to inform you of when it encounters different parts of the docuent structure. The set of method, along with some comments describing their purpose can be seen here.
You don't need to implement all of the
IRtfListener interface yourself, if you wish you can subclass
RtfListenerAdaptor which provides empty methods for all of the
IRtfListener methods. You can then just override the methods you are interested in.
An example text extractor is provided, you can invoke it like this:
new StreamTextConverter().convert(new RtfStreamSource(inputStream), outputStream, "UTF-8");
This code reads an RTF file from the
inputStream and writes the resulting text to the
outputStream in the encoding specified by the last argument.
A second example text extractor is also provided, this one extracts text from the RTF file into a string:
StringTextConverter converter = new StringTextConverter(); converter.convert(new RtfStreamSource(inputStream)); String extractedText = converter.getText();