dscontextlistener.java

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package listener;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.http.HttpServlet;
import javax.sql.DataSource;

public class DSContextListener extends HttpServlet implements
		ServletContextListener {
	private ServletContext context;
	private DataSource ds;

	public void contextInitialized(ServletContextEvent event) {
		try {
			Context initContext=new InitialContext();
			ds=(DataSource) initContext.lookup("java:comp/env/jdbc/mysql");
			context=event.getServletContext();
			context.setAttribute("DataSource", ds);
		} catch (NamingException e) {
			e.printStackTrace();
		}
	}
	
	public void contextDestroyed(ServletContextEvent event) {
		if(context!=null)
		context.removeAttribute("DataSource");
		ds=null;
	}
}