| |
Advantages |
Disadvantages |
| Servlet |
- The most dependable solution.
- Barcode can be inserted in dynamic HTML with the IMG
tag.
- Because a JPEG is generated at the server, it is compatible
with all web browsers.
- Offers better performance for workstations with slower
CPUs.
- Usually less load time on the browser than applets.
|
- More difficult to install and configure.
- Centralized barcode processing and image generation
places more load on the server.
- More load on the server can cause poorer performance
than applets would if the server's CPU is very busy or if
the barcode image generated is greater than the size of
the applet JAR file.
|
| Applet |
- Easy to install and modify.
- Processing occurs at the workstation, which offloads
the processing of barcode images from the server.
- Does not require any custom modifications to the server.
- The small size of the JAR files provides quick applet
load times.
- Quick barcode generation can be achieved over slow connections
by pre-loading applets.
|
- Some installations of NS6 and IE5.5 do not print
applets.
- Although the JAR files are small, the browser must read
the JAR file, which can cause poor performance over slow
dial-up lines. The JAR is about the size of a normal graphic
image and is stored in the browser's cache. This problem
is solved by pre-loading applets.
- Not compatible with browsers that do not have a Java
VM such as NS v1 or old versions of Mosaic.
|
| For
other implementations of creating barcodes on web pages, please
review the
Internet & web pages bar-coding FAQ. |
* The size of the JAR file can be reduced by about 10K
for applet operation by removing all files in the encoder directory
of the JAR file because these are only used for servlets and graphic
file creation.
|
|
IDAutomation's Servlet is compatible with all browsers and is easy to
embed in HTML as an image with the <IMG>
tag. See
example or
view the
Servlet demo.
Purchase or
Download the
Java Barcode Packages now.
Creating secure servlets:
Programmers that modify the servlet source code provided can accomplish
other methods of servlet operation. This may be necessary to prevent
the end-user from manipulating the servlet. A working example is provided
in the IDAutomationSecureServlet.java file,
which is in the source code ZIP file of the linear package.
The following code is an example of the java class library being
used as a custom secure servlet:
//*****************************************************************
//
// JAVA Source for com.idautomation.linear; 3.1
//
// Copyright, IDAutomation.com, Inc. 2000-2004.
// All rights reserved.
//
// http://www.IDAutomation.com/java/
//
// NOTICE:
// You may incorporate our Source Code in your application
// only if you own a valid Java Developer License
// from IDAutomation.com, Inc. and the copyright notices
// are not removed from the source code.
//
//*****************************************************************
package com.idautomation.linear;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.awt.Graphics2D.*;
import java.awt.*;
public class IDAutomationSecureServlet extends HttpServlet
{
/**
* Handle the HTTP POST method by sending an e-mail
*
*
*/
private boolean debug=false;
public void init() throws ServletException {
}
// MODIFY THIS METHOD TO RETRIEVE DATA TO ENCODE,
CREATE THE BARCODE
AND SET THE PARAMETERS
private BarCode getChart (HttpServletRequest request) {
BarCode cb=new BarCode();
cb.code="SecureServlet";
return cb;
}
// Handle the request
// 1. create barcode
// 2. draw barcode in a Buffered Image
// 3. encode image as GIF or JPEG and send it to the browser
public void doGet (HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException
{
PrintWriter out;
ServletOutputStream outb;
//default encoding type
String encode="jpeg";
if (request!=null) {
if (request.getParameter("FORMAT")!=null) encode=request.getParameter("FORMAT").toLowerCase();
if (encode.compareTo("gif")!=0) encode="jpeg";
}
response.setContentType("image/"+encode);
outb=response.getOutputStream();
// avoid caching in browser
response.setHeader ("Pragma", "no-cache");
response.setHeader ("Cache-Control", "no-cache");
response.setDateHeader ("Expires",0);
try {
// find sizes
int w=10;
int h=10;
// get the BarCode
BarCode cb=getChart(request);
if ((request!=null) && (request.getParameter("WIDTH")!=null) && (request.getParameter("HEIGHT")!=null))
{
w=new Integer(request.getParameter("WIDTH")).intValue();
h=new Integer(request.getParameter("HEIGHT")).intValue();
}
else {
//a temp image must be created to find the preferred size
cb.autoSize=true;
cb.setSize(170,90);
java.awt.image.BufferedImage imageTemp = new
java.awt.image.BufferedImage(
cb.getSize().width,cb.getSize()
.height,java.awt.image.BufferedImage.TYPE_BYTE_INDEXED
);
java.awt.Graphics imgTempGraphics = imageTemp.createGraphics();
cb.paint(imgTempGraphics);
cb.invalidate();
w=cb.getSize().width;
h=cb.getSize().height;
imgTempGraphics.dispose();
}
java.awt.image.BufferedImage BarImage=new java.awt.image.BufferedImage
(w,h,java.awt.image.BufferedImage.TYPE_INT_RGB);
java.awt.Graphics2D BarGraphics=BarImage.createGraphics();
if (debug) System.out.println("Size: "+w+" "+h);
cb.setSize(w,h);
cb.paint(BarGraphics);
if (encode.compareToIgnoreCase("gif")==0) {
// encode buffered image to a gif
// NOTICE - REMARKED NEXT 2 LINES OUT UNTIL UNISYS PATENT EXPIRES
cb.setSize(w,h);
//com.idautomation.linear.encoder.GifEncoder encoder = new com.idautomation.linear.encoder.GifEncoder(BarImage
,outb);
//encoder.encode();
}
else
{
// create JPEG image
com.sun.image.codec.jpeg.JPEGImageEncoder encoder = com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder(outb
);
//increase the JPEG quality to 100%
com.sun.image.codec.jpeg.JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(
BarImage);
param.setQuality(1.0F,true);
encoder.setJPEGEncodeParam(param);
encoder.encode( BarImage,param );
}
} catch (Exception e) { e.printStackTrace();}
}
public void doPost (HttpServletRequest request,
HttpServletResponse response)
throws ServletException
{
try {
doGet(request,response);
} catch (Exception e) { e.printStackTrace();}
}
} |
