RequestDispatcher Interface and SendRedirect() Method

RequestDispatcher Interface 

public interface RequestDispatcher
Defines an object that receives requests from the client and sends them to any resource (such as a servlet, HTML file, or JSP file) on the server. 

public RequestDispatcher getRequestDispatcher(String path) 
Returns a RequestDispatcher object that acts as a wrapper for the resource located at the given path. A RequestDispatcher object can be used to forward a request to the resource or to include the resource in a response. The resource can be dynamic or static. 

RequestDispatcher has two methods:
1. include method
2. forward method 

public void include(ServletRequest request, ServletResponse response) throws ServletException, IOException 
Includes the content of a resource (servlet, JSP page, HTML file) in the response. In essence, this method enables programmatic server-side includes. 

public void forward(ServletRequest request,ServletResponse response)throws ServletException,java.io.IOException
Forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server.

login.java

 ResultSet rs=st.executeQuery("select * from login where Uname='"+s1+"'and Upass='"+s2+"'");  
    if(rs.next())  
        {  
         RequestDispatcher rd=request.getRequestDispatcher("validUser");  
         rd.forward(request, response);  
       }  
    else  
     {  
         out.print("invalid user");  
      RequestDispatcher rd=request.getRequestDispatcher("Register.jsp");  
     rd.include(request, response);  
    }  

SendRedirect() Method

public void sendRedirect(String location) throws IOException
Sends a temporary redirect response to the client using the specified redirect location URL and clears the buffer.

login.java

 ResultSet rs=st.executeQuery("select * from login where Uname='"+s1+"'and Upass='"+s2+"'");  
    if(rs.next())  
        {  
         response.sendRedirect("validUser");  
       }  
    else  
     {  
         out.print("invalid user");  
         response.sendRedirect("Register.jsp");
    }  

web.xml

  <?xml version="1.0" encoding="UTF-8"?>  
   <servlet>  
     <servlet-name>login</servlet-name>  
     <servlet-class>login</servlet-class>  
   </servlet>    
   <servlet>  
     <servlet-name>validUser</servlet-name>  
     <servlet-class>validUser</servlet-class>  
   </servlet>  
   <servlet-mapping>  
     <servlet-name>login</servlet-name>  
     <url-pattern>/login</url-pattern>  
   </servlet-mapping>  
   <servlet-mapping>  
     <servlet-name>validUser</servlet-name>  
     <url-pattern>/validUser</url-pattern>  
   </servlet-mapping>  
   <session-config>  
     <session-timeout>  
       30  
     </session-timeout>  
   </session-config>  
   <welcome-file-list>  
     <welcome-file>index.jsp</welcome-file>  
   </welcome-file-list>  
 </web-app>  

Download Code Link 1
Download Code Link 2

More Servlet Topics :

• Introduction : Servlet Interface
• Java Package javax.servlet(Interfaces,Classes and Methods)
• Java Package javax.servlet.http (Interfaces,Classes and Methods)
• How to Create a Web Application using NetBeans and Apache Tomcat Server
• Basic Program using HttpServlet Class 
• Basic Login Program using JSP and GenericSevlet class
• Login using JDBC,Servlet with NetBeans and Oracle 
• SevletConfig Interface using JDBC,NetBeans 6.9 and Oracle 10g 
• Validation on TextField using JavaScript and Print command using servlet on NetBeans 
• ServletContext Interface 
• RequestDispatcher Interface and SendRedirect() Method 
• Session Tracking 
• Session Tracking using Cookies  
• Session Tracking using HttpSession Interface 
• Session Tracking using URL Rewriting  
• Session Tracking using Hidden Forms Field 
• Sql Query Tool using Servlet