Servlets are Java programs that run on a Web server and build Web pages. Here are a few definitions:
- Servlet Development Kits
Java Servlet Development Kit (JSDK) provides Servlet API classes (servlet.jar). Place servlet.jar into CLASSPATH, so that java classes can access it.
- Servlet Engines
A servlet is a Java class that needs to be executed in a Java VM by servlet engine. The servlet engine loads the servlet class the first time the servlet is requested. The servlet then stays loaded to handle multiple requests until it is explicitly unloaded or the servlet engine is shut down.
Following are few WebServers that supports servlets:
- Apache Tomcat
- BEA WebLogic
- IBM Websphere
- Sun's Java Web Server (JWS)
- Apache Tomcat.
- Java Servlet Development Kit (JSDK)
Apache Tomcat is a servlet container used for Java Servlet and JavaServer Pages technologies.
Example below describes the development of servlet with Apache Tomcat.
Download Tomcat from http://jakarta.apache.org/tomcat/index.html and follow the instruction for installation.
Servlets are java classes they can be compiled with java compiler. eg -javac myservlet.java.
For deployment of servlet, it has to be placed in the specified directory structure below:
- XML file describing servlet are placed in Webapps/WEB-INF/web.xml
- Servlet java classes are placed in Webapps/WEB-INF/classes
- External Library files like jdbc are placed in Webapps/WEB-INF/lib
Open any browser and type http:\\localhost:8080\yourservlet.