Using Tomcat

Using Tomcat

Tomcat contains the class libraries, documentation, and run-time support that you will need to create and test servlets. At the time of this writing, several versions of Tomcat are available. The instructions that follow use 7.0.47. You can download Tomcat from tomcat.apache.org. You should choose a version appropriate to your environment.

The examples in this chapter assume a 64-bit Windows environment. Assuming that a 64-bit version of Tomcat 7.0.47 was unpacked from the root directly, the default location is

C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\

This is the location assumed by the examples in this book. If you load Tomcat in a different location (or use a different version of Tomcat), you will need to make appropriate changes to the examples. You may need to set the environmental variable JAVA_HOME to the top-level directory in which the Java Development Kit is installed.

Once installed, you start Tomcat by selecting startup.bat from the bin directly under the apache-tomcat-7.0.47 directory. To stop Tomcat, execute shutdown.bat, also in the bin directory.

The classes and interfaces needed to build servlets are contained in servlet-api.jar, which is in the following directory:

C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\lib

To make servlet-api.jar accessible, update your CLASSPATH environment variable so that it includes

C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\lib\servlet-api.jar

Alternatively, you can specify this file when you compile the servlets. For example, the following command compiles the first servlet example:

javac HelloServlet.java -classpath "C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\lib\servlet-api.jar"

Once you have compiled a servlet, you must enable Tomcat to find it. For our purposes, this means putting it into a directory under Tomcat’s webapps directory and entering its name into a web.xml file. To keep things simple, the examples in this chapter use the directory and web.xml file that Tomcat supplies for its own example servlets. This way, you won’t have to create any files or directories just to experiment with the sample servlets. Here is the procedure that you will follow.

First, copy the servlet’s class file into the following directory:

C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\webapps\ examples\WEB-INF\classes

Next, add the servlet’s name and mapping to the web.xml file in the following directory:

C:\apache-tomcat-7.0.47-windows-x64\apache-tomcat-7.0.47\webapps\ examples\WEB-INF

For instance, assuming the first example, called HelloServlet, you will add the following lines in the section that defines the servlets:

<servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>HelloServlet</servlet-class>

</servlet>

Next, you will add the following lines to the section that defines the servlet mappings:

<servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/servlet/HelloServlet</url-pattern>

</servlet-mapping>

Follow this same general procedure for all of the examples.