SatyaCodes

Servlets- ServletConfig

ServletConfig

  • ServletConfig is one of the pre-defined interface.

  • ServletConfig object exists one per servlet program.

  • An object of ServletConfig created by the container during its initialization phase.

  • An object of ServletConfig is available to the servlet during its execution, once the servlet execution is completed, automatically ServletConfig interface object will be removed by the container.

  • **It contains details at web.xml, of a particular servlet.**

  • The moment when we are using an object of ServletConfig, **we need to configure the web.xml by writing tag under tag of web.xml**.


How to get ServletConfig Object

We can ServletConfig object in 2 ways

1. By calling getServletConfig() on current servlet

ServletConfig conf = getServletConfig();

Above method is available in Servlet interface, inherited in to GenericServlet & HttpServlet

2. ServletConfig object will be available in init() method of the servlet.

public void init(ServletConfig config)
{
// …………………
}


How to place <init-param> in web.xml

We have to place <init-param> in between **** tags

public class LoginServlet extends HttpServlet {
	protected void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException {
 PrintWriter pw = res.getWriter();
 res.setContentType("text/html");

 ServletConfig cfg = getServletConfig();
 pw.write("<h3> 1. Using getInitParameter()");
 pw.write("<br> s1 : " + cfg.getInitParameter("s1"));
 pw.write("<br> s2 :" + cfg.getInitParameter("s2"));

 pw.write("<br><br>  2. Using getInitParameterNames()");
 Enumeration e = cfg.getInitParameterNames();
 while (e.hasMoreElements()) {
 	String s = (String) e.nextElement();
 	pw.write("<br>" +s + "\t : " + cfg.getInitParameter(s));
 }
	}
}

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