CHAPTER 11 (Web hosting script) ADVANCED FILTERING TECHNIQUES 449 the
CHAPTER 11 ADVANCED FILTERING TECHNIQUES 449 the same time. Following the filter life cycle, however, there s a natural place to set the value of your initialization parameters. After an instance of a filter has been created, and before the very first doFilter() is called, the container calls the init() method to set the FilterConfig object for the filter. This is a natural point at which to perform any initialization required, and it s conceptually equivalent to the init() method of a servlet. In this case, you ll take advantage of it by setting your instance variables with values from the filter definition. Listing 11-10 shows the init() method for the StopGamesFilter. The container always calls init() in a single thread when it sets up the filter instance. In the init() method, the filterConfig.getInitParameter()method reads the web.xml file for initialization parameters. The init() method in Listing 11-10 replaces the init() method in Listing 11-9. Listing 11-10. init() (To Be Added to StopGamesFilter.java) public void init(FilterConfig arg0) throws ServletException { String tpString; filterConfig = arg0; if ((tpString = filterConfig.getInitParameter(”starthour”)) != null) starthour = Integer.parseInt(tpString, 10); if ((tpString = filterConfig.getInitParameter(”stophour”)) != null) stophour = Integer.parseInt(tpString, 10); } Installing and Configuring the StopGamesFilter To install and configure the filter, first make sure all other
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