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iText Document Generator: PDF Generation Made Easy
by Benoy Jose
The portable document format (PDF) is the most commonly used document format in the industry, mainly due to its simplicity and portability. PDF has become the standard format for generating company reports, brochures, and presentations. Hence today's applications are expected to generate reports in numerous formats including HTML, rich text, and PDF. Most application servers and other server software provide direct support for generating HTML, text, and rich text documents, but there are no application servers that provide PDF document-generation support. iText is a Java based API that fills this gap by providing a simple, easy-to-use PDF document generator.
iText has a simple API, which can be used to simultaneously generate PDF, rich text, and HTML documents.
Features
- Easy-to-use Java API
- Writes to any Java output stream
- Generates multiple outputs like HTML, RTF, and PDF simultaneously.
- Supports for underlining, strike-through text, skewed text, subscript, and superscript
- Nested Tables
- Watermarks
- Security and Encryption
- Extended font support
- Barcode support
- Event support
- Parses existing PDF files
- Support for Adobe JavaScript
- XML Support
- Templates
Installation and Setup
The iText API requires no installation. Just download the iText.jar file from the iText Web site and include it into the class path. To use iText in an application server, place the iText.jar into a directory where the application server can read it.
Example
Let's start with an example of how to create a simple PDF document. To generate a PDF, first create an instance of the Document class. Next, create an instance of the PdfWriter passing the already created Document object and the output stream where the PDF document needs to be pushed.
Document d = new Document (PageSize.A4);
PdfWriter.getInstance (d, new FileInputStream ("sample.pdf"));
d.open ();
Paragraph p = new Paragraph ("Some sample Text");
d.add (p);
d.close ();
Output Formats
Apart from the standard PDF format, iText can generate documents in RTF and HTML formats.
- RTF Writer: This implements most of the functionality provided in the PDF writer with a few exceptions. It doesn't support watermarks, encryption, lists, nested tables, image rotation, viewer preferences, or embedded fonts. There are two versions of the RtfWriter in the iText API: RftWriter and RtfWriter2. The new vesions of iText will use the RftWriter2 and all future enhancements will be done on that writer. The old RftWriter is still included in the jar for backward compatibility. The RtfWriter supports some RTF-specific features like extended font, extended header/footer, extended cell, table of contents and page number.
- HTML Writer: This is not an advanced HTML Document creator; it produces a bare bones HTML document with the same features that exist in the PdfWriter. It is useful only if you need to generate documents in multiple formats simultaneously. If you want to generate only HTML documents, iText might not be a good choice.
Events
The PdfWriter translates all text and data added to the Document object into the PDF format. Though the Document object acts as an interface to all data being added to the PDF file, it has limited control over how and when the data is generated in the PDF. For instance, the user might need to add a new header for every page after the first page. The iText API provides page and table events, which give the user more control over how and when data is added to a PDF page.
- Page Events: To capture events in a page, the calling class has to either implement the PdfPageEvent interface or extend the PdfPageEventHelper class. The PdfPageEvent interface provides a number of methods like onOpenDocument, onCloseDocument, onStartPage, onEndPage, onParagraph, onChapter, etc. If you choose to implement only a few methods in this list, you may use the PdfPageEventHelper class, which has empty implementations of the PdfPageEvent interface. The first event that is triggered when a document is started in onOpenDocument. This immediately triggers the onStartPage event. Other events, like onParagraph and onSection, can be used to decide on the positioning of a paragraph relative to the previous paragraph.
- Table Events: The table events can be used only in a PDF document. The events are triggered off the PdfPTable class that is used in generating PDF tables.
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