13.4 A Guest Book Servlet

You have probably heard quite a bit about Java applets. We discussed in Chapter 8, however, how doing database access in the client is a really bad idea. We have packaged with the examples in this book a servlet that uses the JDBC knowledge we have discussed in this chapter to store the comments from visitors to a web site in a database and display the comments in the database. While servlets are not in themselves part of the three-tier solution we discussed in Chapter 8, this example should provide a useful example of how JDBC can be used. For this example, all you need to know about servlets is that the doPost( ) method handles HTTP POST events, and doGet( ) handles HTTP GET events. The rest of the code is either simple Java code or an illustration of the database concepts from this chapter. You can see the servlet in action at http://www.imaginary.com/~george/personal/guestbook.shtml.