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Java Pro Programming: Printing

Learn how to use the print service API

By Brett Spell, JavaWorld.com, 07/25/05

Java matured very quickly in most respects after it was first introduced, but for a long time, printing was one of Java's weakest points. In fact, Java 1.0 didn't offer any support for printing at all. Java 1.1 included a class called PrintJob in the java.awt package, but the printing capabilities supported by that class were somewhat crude and unreliable. When Java 1.2 (or "Java 2") was introduced, it included a completely separate mechanism (called the Java 2D printing API) for printing designed around PrinterJob and other classes and interfaces defined in the new java.awt.print package. This rendered the PrintJob-based printing mechanism (also known as AWT printing) largely obsolete, although PrintJob has never been deprecated and, at least of this writing, is still technically a supported class.

Additional changes were made in J2SE 1.3 when PrintJob's capabilities expanded to allow the setting of job and page attributes using the appropriately named JobAttributes and PageAttributes classes within the java.awt package. With the release of J2SE 1.3, the printing capabilities were reasonably robust, but some problems still existed aside from the confusion associated with having two completely separate printing facilities. For one thing, both facilities used an implementation of the java.awt.Graphics class for rendering the content to be printed, which meant anything that needed to be printed had to be rendered as a graphical image. In addition, the newer and generally more robust PrinterJob facility provided only limited support for setting attributes associated with the job. Finally, neither facility provided a way to programmatically select the target printer.

The biggest change in Java's printing capabilities to date came with the release of J2SE 1.4, when the Java print service API was introduced. This third implementation of printing support in Java addressed the limitations that were just described using an implementation of the PrintService and DocPrintJob interfaces defined in the javax.print package. Because this new API represents a superset of the functionality defined by the two older printing facilities, it's the one you should normally use and will be the focus of this article.

At a high level, the steps involved in using the Java print service API are straightforward:

1. Locate print services (printers), optionally limiting the list of those returned to the ones that support the capabilities your application needs. Print services are represented as instances of PrintService implementations.
2. Create a print job by calling the createPrintJob() method defined in the PrintService interface. The print job is represented by an instance of DocPrintJob.
3. Create an implementation of the Doc interface that describes the data you want to print. You also have the option of creating an instance of PrintRequestAttributeSet that describes the printing options you want.
4. Initiate printing by calling the print() method defined in the DocPrintJob interface, specifying the Doc you created in the previous step and the PrintRequestAttributeSet or a null value.

You'll now examine each of these steps and see how to achieve them.

 

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