Code 128 is a very effective, high-density symbology which permits the encoding of alphanumeric data. The symbology includes a checksum digit for verification, and the bar code may also be verified character-by-character verifying the parity of each data byte. This symbology has been widely implemented in many applications where a relatively large amount of data must be encoded in a relatively small amount of space. It's specific structure also allows numeric data to be encoded at, effectively, double-density.

Code 128 Code Sets

• Code Set A (or Chars Set A) includes all of the standard upper case U.S. alphanumeric keyboard characters and punctuation characters together with the control characters, (i.e. characters with ASCII values from 0 to 95 inclusive), and seven special characters.
• Code Set B (or Chars Set B) includes all of the standard upper case alphanumeric keyboard characters and punctuation characters together with the lower case alphabetic characters (i.e. characters with ASCII values from 32 to 127 inclusive), and seven special characters.
• Code Set C (or Chars Set C) includes the set of 100 digit pairs from 00 to 99 inclusive, as well as three special characters. This allows numeric data to be encoded as two data digits per symbol character, at effectively twice the density of standard data.

Code 128 Special characters

The last seven characters of Code Sets A and B (character values 96 - 102) and the last three characters of Code Set C (character values 100 - 102) are special non-data characters with no ASCII character equivalents, which have particular significance to the bar code reading device.

Sample of a Code 128 Barcode

The following code illustrates how to create a barcode in a Java class

1            Barcode barcode = new Barcode(); 
2            barcode.setData("123456789"); 
3            barcode.setType(Barcode.CODE39); 
4            barcode.createBarcodeImage("c:/code39.gif"); 

• Create a Barcode object (line 1)
• set Barcode object properties (line 2 - 3)
• save into gif file (line 4)

There are two ways to create barcode images in your Java web applications.

1. This is the simplest way to stream barcode image using our provided barcode servlet classes.
   
   And it will not save barcode images in your server side.
   
   
   • Under demo package, copy barcode folder to your java servlet container like tomcat.
     
     
   • To test your installation, goto http://YourDomain:Port/barcode/barcode?Data=123456789&Type=CODE39
     
     
   • To create barcode image in your JSP page, you can pass the url to IMG tag src value. For example, <img src="http://YourDomain:Port/barcode/barcode?Data=123456789&Type=CODE39" />
     
     
2. The second method is similar with the way to generate barcode in Java applications.
   
   
   • Create a barcode image in server side

     1            Barcode barcode = new Barcode(); 
     2            barcode.setData("123456789"); 
     3            barcode.setType(Barcode.CODE39); 
     4            barcode.createBarcodeImage("C:/Tools/Tomcat 5.5/webapps/YourWebApp/bimages/code39.gif"); 
     
     
     

   • In your JSP page, you can using IMG tag to display generated image, like <img src="http://YourDomain:Port/YourWebApp/bimages/code39.gif" />

The following jasper xml content illustrates how to insert a barcode into JasperReports

<import value="com.barcodelib.barcode.BarcodeFactory"/> 

Import class BarcodeFactory to report.

<image scaleImage="Clip" hAlign="Center"> 
    <reportElement x="50" y="110" width="515" height="120"/> 
    <graphicElement/> 
    <imageExpression class="net.sf.jasperreports.engine.JRRenderable">
     <![CDATA[new com.barcodelib.barcode.BarcodeJasperRenderer(BarcodeFactory.createLinear(13, "0470821632"))]]></imageExpression> 
</image>

Please go to class BarcodeFactory in Java doc for all methods to create linear barcode.

Developers also can extend BarcodeFactory class to meet their own requirements. Complete BarcodeFactory.java Source Code