Java Glossary : printing

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There are two kinds of printing:

When you know the brand of printer you have and the control codes it likes, and you want to send raw bytes to it. Most often you want to do this when your printer handles PostScript.
parallel port ¤ System.exec
You don't know what kind of printer you have. You want to use generic methods and have the operating system convert them into the codes the printer likes. For this technique to work, the printer must be configured in the OS with a device driver, and be accessible to your program as the default printer.

For the rest of this discussion, we are referring only to the second type printing. Within that, there are three different APIs to choose from.

Since Java 1.1: java.awt.PrintJob and related classes.
Since Java 1.2: java.awt.print packages.
In Java 1.3: significant enhancements to both packages.
Since Java 1.4: The Java Print Service (JPS) javax.print packages.

The Java 1.0 JDK does not support printing. JDK 1.1 does, via java.awt.PrintJob. You print using the same techniques you use for drawing on the screen. It is much like drawing a high-res screen the size of a sheet of paper. Components now have a print method to print themselves which is usually the same as the one to draw them on the screen. To handle text you use Canvases and drawString, or TextFields. To get properly aligned text without borders, consider the KL-Group components or Swing. Applets cannot print, with one exception, signed Applets running under IE4 in JDK 1.1. For example to print everything in a frame:

PrintJob pj = getToolkit( ).getPrintJob(theFrame, jobTitle, null /* properties */ );
// get Printjob object.

Graphics pg = pj.getGraphics();
// get Graphics object for the first page.

printAll(pg);
// print this component and its subcomponents, at (0,0).

pg.dispose();
// release the first page to the print queue.

pg = pj.getGraphics();
// get graphics object for second page.

pg.drawLine(0, 0, 100, 100 );
// draw directly onto the graphics object as if it were a Canvas.

pg.dispose();
// release the second page to the print queue.

pj.end();
// Finish off the print job, start printing.

In Win95 and NT, the print job properties are ignored. They are system dependent. But here is how Sun implements them:

howPrint.put( "awt.print.destination", "printer" );
// could be "printer" or "file", default "printer"

howPrint.put( "awt.print.fileName", "TEMP/TEMP.PRN" );
// file to receive the PostScript or other physical printer commands

howPrint.put( "awt.print.numCopies", "1" );
// default 1

howPrint.put( "awt.print.orientation", "portrait" );
// could be "portrait" or "landscape", default "portrait"

howPrint.put( "awt.print.paperSize", "letter" );
// could be "letter","legal","executive " or "a4". default "letter"

howPrint.put( "awt.print.printer", "lp" )
// name of command/utility that will do the printing

howPrint.put( "awt.print.options", "" );
// options to pass to the print command/utility

PrintJob pj = getToolkit().getPrintJob(theFrame, "Print Test #1", howPrint );
Graphics pg = pj.getGraphics();
printAll(pg);
pg.dispose();
pj.end();

Here is a little PostScript grid.ps program.

copy grid.ps lpt1:

(where lpt1: is a PostScript printer) to print out a 1/10" by 1/6 " grid on transparent film. It will be useful in designing or checking printouts, especially those on pre-printed forms. Programmers were not happy with the AWT print interface and Sun has made been several attempts to replace the API. This has mainly lead to confusion. The key is to get clear on just which printing API you are using and stick to it.

Java Print Service : available:

on the web at java.Sun.com
on J: in the JDK 1.4.2_04: J:\j2sdk1.4.2_04\docs\guide\jps\index.html
on J: in the JDK 1.5 beta: J:\Program Files\Java\j2sdk1.5.0\docs\guide\jps\index.html

Bravo ¤ JDK ¤ PDF ¤ PostScript

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