Compiling and Installing the Servlet

Note that the specific details for installing servlets vary from Web server to Web server. Please refer to your Web server documentation for definitive directions. The on-line examples are running on Java Web Server (JWS) 2.0, where servlets are expected to be in a directory called servlets in the JWS installation hierarchy. However, I placed this servlet in a separate package (hall) to avoid conflicts with other servlets on this server; you'll want to do the same if you are using a Web server that is used by other people and doesn't have a good infrastructure for "virtual servers" to prevent these conflicts automatically. Thus, HelloWorld.java actually goes in a subdirectory called hall in the servlets directory. Note that setup on most other servers is similar, and the servlet and JSP examples in the tutorial have also been tested using BEA WebLogic and IBM WebSphere 3.0. WebSphere has an excellent mechanism for virtual servers, and it is not necessary to use packages solely to prevent name conflicts with other users.

If you've never used packages before, there are two main ways to compile classes that are in packages.

One way is to set your CLASSPATH to point to the directory above the one actually containing your servlets. You can them compile normally from within the directory. For example, if your base directory is C:\JavaWebServer\servlets and your package name (and thus subdirectory name) is hall, and you were on Windows, you'd do:
DOS> set CLASSPATH=C:\JavaWebServer\servlets;%CLASSPATH%
DOS> cd C:\JavaWebServer\servlets\hall
DOS> javac YourServlet.java
The first part, setting the CLASSPATH, you probably want to do permanently, rather than each time you start a new DOS window. On Windows 95/98 you'd typically put the "set CLASSPATH=..." statement in your autoexec.bat file somewhere after the line that set the CLASSPATH to point to servlet.jar and jsp.jar. On Windows NT, you'd go to the Start menu, select Settings, select Control Panel, select System, select Environment, then enter the variable and value. Note also that if your package were of the form name1.name2.name3 rather than simply name1 as here, you'd still have the CLASSPATH point to the top-level directory of your package hierarchy (the one containing name1).

A second way to compile classes that are in packages is to go to the directory above the one containing your servlets, and then do "javac directory\YourServlet.java" (Windows; note the backslash) or "javac directory/YourServlet.java" (Unix; note the forward slash). For example, suppose again that your base directory is C:\JavaWebServer\servlets and your package name (and thus subdirectory name) is hall, and you were on Windows. In that case, you'd do the following:
DOS> cd C:\JavaWebServer\servlets
DOS> javac hall\YourServlet.java
Note that, on Windows, most JDK 1.1 versions of javac require a backslash, not a forward slash, after the directory name. This is fixed in JDK 1.2, but since many Web servers are configured to use JDK 1.1, many servlet authors stick with JDK 1.1 for portability.

Finally, another advanced option is to keep the source code in a location distinct from the .class files, and use javac's "-d" option to install them in the location the Web server expects.