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Initializing a Servlet

After the Web container loads and instantiates the servlet class and before it delivers requests from clients, the Web container initializes the servlet. You can customize this process to allow the servlet to read persistent configuration data, initialize resources, and perform any other one-time activities by overriding the init method of the Servlet interface. A servlet that cannot complete its initialization process should throw UnavailableException.

All the servlets that access the bookstore database (BookStoreServlet, CatalogServlet, BookDetailsServlet, and ShowCartServlet) initialize a variable in their init method that points to the database helper object created by the Web context listener:

public class CatalogServlet extends HttpServlet {
  private BookDB bookDB;
  public void init() throws ServletException {
    bookDB = (BookDB)getServletContext().
      getAttribute("bookDB");
    if (bookDB == null) throw new
      UnavailableException("Couldn't get database.");
  }
}
 

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This tutorial contains information on the 1.0 version of the Java Web Services Developer Pack.

All of the material in The Java Web Services Tutorial is copyright-protected and may not be published in other works without express written permission from Sun Microsystems.