Writing Servlets
Setting The CLASSPATH
At this point we should emphasize that the Servlet API is not part of the core JDK itself.
The Servlet API is stored in a class hierarchy that starts with "javax".
Javax is an abbreviation for Java eXtension.
Java eXtensions are downloaded separately from the JDK.
The Servlet extensions happen to be contained in the JSWDK that we downloaded.
However, although we downloaded the JSWDK, there is still one other thing left to do.
We must set up our Java CLASSPATH to include the servlet.jar file.
This file contains the Servlet API inside of a javax class hierarchy.
Assuming you installed the JSWDK to the c:\jswdk-1.0.1\ directory, you need to add the following to your CLASSPATH environment variable.
c:\jswdk-1.0.1\lib\servlet.jar
To add this file to the CLASSPATH under Win95/Win98, add the following command to the autoexec.bat file.
set CLASSPATH=c:\jswdk-1.0.1\lib\servlet.jar;%CLASSPATH%
On Windows NT, you can enter the CLASSPATH variable and value under the Environment panel of the Systems setting area in the Control panel.
You can load the Control Panel from the Settings area of the Start menu.
On UNIX, you can use the mechanism for setting the environment that suits your particular shell and pass a UNIX-style path to the servlet.jar file.
Specific instructions for your UNIX system are typically provided as part of the UNIX-specific download of the JSWDK.
Now that we have established a Servlet-aware tutorial directory and established the CLASSPATH to the servlet.jar file, we can get started writing a servlet.
Tip:
You can compile the code directly in the servlets subdirectory, but you may find it easier to keep track of your files if you create another subdirectory devoted to managing your source code.
For security reasons, you would most likely not want to have your source code sitting in the same directories as the compiled servlet classes, at least on a production web server.
So, you may want to start keeping your source code separate from your servlet web server directories.
NEXT
Gunther Birznieks contributes to JavaBoutique's Web/Networking column.
Gunther currently works for Barclays Capital in London, one of the leading global investment banks in Europe and has previously worked as a senior computer scientist in the Human Genome Project.
Gunther is also known for writing several books on Web Programming (Perl, CGI, Java) as well as for co-creating Extropia with Selena Sol.
Extropia is one of the best known public domain web programming archives
Email: gunther@extropia.com.
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