ServletConfig
is an interface of servlet API. Implementation of which is provided by vendors.
An object of type ServletConfig is
created by the server for each servlet.
This object has following use:
This object has following use:
1- It is
used by the server to provide Servlet specific initialization parameter to
Servlets.
Servlets.
2- It is
used by the server to provide reference of the ServletContext object to the Servlet.
2.2- ServletConfig object is created for the Servlet.
2.3- <init-param> (if define for the Servlet) are read and store in it.
2.4- Reference of ServletContext is saved in it.
3.0- Server call the init() method of Servlet and provide the reference of ServletConfig.
Method of
javax.servlet.ServletConfig interface:
1- getServletContext():
Is used to obtain reference of ServletContext object.
public ServletContext getServletContext();
2- getInitParameter():
Is used to obtain the values of initialization parameter.
public String getInitParameter(String PName);
Is used to obtain reference of ServletContext object.
public ServletContext getServletContext();
2- getInitParameter():
Is used to obtain the values of initialization parameter.
public String getInitParameter(String PName);
3- getInitParameterNames():
Is used to obtain the name of initialization parameters.
public Enumeration getInitParameterNames();
Is used to obtain the name of initialization parameters.
public Enumeration getInitParameterNames();
Example
1- program to access ServletConfig initialization parameter (Which is Servlet
scope)
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Program
save with Name: index.html
<html>
<head><title>Login
Page</title></head>
<body>
<form method="get" action="loginServlet">
UserId : <input type="text"
name="txtUserId"><br>
Password : <input
type="password" name="txtPassword"><br>
<input type="submit"
value="Login">
</form>
</body>
</html>
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Program
save with Name: LoginServlet.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.sql.*;
public class LoginServlet extends
HttpServlet
{
public
void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException
{
try
{
response.setContentType("text/html");
PrintWriter
out=response.getWriter();
String
id=request.getParameter("txtUserId");
String
pwd=request.getParameter("txtPassword");
ServletConfig
cnf=getServletConfig();
/*
First get ServletConfig object reference Because
ServletConfig object contains the Servlet
scope initilization parameter <init-param> */
Class.forName(cnf.getInitParameter("driverName"));
Connection
con=DriverManager.getConnection(cnf.getInitParameter("url"),cnf.getInitParameter("userName"),cnf.getInitParameter("password"));
PreparedStatement
stmt=con.prepareStatement("select * from userInfo where id=? and
password=?");
stmt.setString(1,id);
stmt.setString(2,pwd);
ResultSet
rset=stmt.executeQuery();
if(rset.next())
{
out.println("<b>Welcome,
"+rset.getString(2)+"</b>");
}
else
{
out.println("<b>
Invalid UserId or Password....<b><br>");
RequestDispatcher
rd=request.getRequestDispatcher("/index.html");
rd.include(request,response);
}
con.close();
out.close();
}
catch(Exception
e)
{
System.out.println(e);
}
}
}
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Program
save with Name: web.xml
<web-app>
<servlet>
<servlet-name>s1</servlet-name>
<servlet-class>LoginServlet</servlet-class>
<init-param>
<param-name>driverName</param-name>
<param-value>oracle.jdbc.driver.OracleDriver</param-value>
</init-param>
<init-param>
<param-name>url</param-name>
<param-value>jdbc:oracle:thin:@localhost:1521:xe</param-value>
</init-param>
<init-param>
<param-name>userName</param-name>
<param-value>system</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value>oracle</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>s1</servlet-name>
<url-pattern>loginServlet</url-pattern>
</servlet-mapping>
</web-app>
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Output :
If valid userId and password then display:
Welcome, rupendra
If invalid userId or password then display:
Invalid UserId or Password....
and include index.html page
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