The Java Servlet Development Tool (JSDK) provides multiple packages that need to be used to use these packages when writing servlets. These include two basic packages for all servlets: javax.servlet and javax.servlet.http. Java servlet development tools can be downloaded from Sun's Web Sites. The following mainly introduces the HTTP Servlet application programming interface provided by javax.servlet.http. HTTP Servlet uses an HTML form to send and receive data. To create an HTTP Servlet, extend the HTTPServlet class, which is a subclass of the genericServlet for the HTML table with a dedicated method. The HTML form is defined by