Request dispacther interface ppt
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The RequestDispatcher interface in Java allows servlets to dispatch or forward requests to other resources on the server like HTML files, JSP pages, or other servlets. It provides two main methods - forward() to forward a request and include() to include the response of a resource in the current response. The getRequestDispatcher() method of the ServletRequest interface returns a RequestDispatcher object that can then be used to call the forward() or include() methods, passing the request and response objects. An example is provided of a login servlet that uses RequestDispatcher to forward successfully authenticated requests to a welcome servlet or include an error message on failed authentication.
Request dispacther interface ppt
- 1. ADVANCED JAVA REQUEST DISPATCHER INTERFACE Prepared by: Taha Malampattiwala – 140050107052
- 2. Introduction to Request Dispatcher RequestDispatcher is an interface, implementation of which defines an object which can dispatch request to any resources(such as HTML, Image, JSP, Servlet) on the server. Methods of RequestDispatcher RequestDispatcher interface provides two important methods. Methods Description void forward(ServletRequest request, ServletResponse response) forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server void include(ServletRequest request, ServletResponse response) includes the content of a resource (servlet, JSP page, HTML file) in the response
- 3. How to get an Object of RequestDispatcher getRequestDispatcher() method of ServletRequest returns the object of RequestDispatcher. RequestDispatcher rs = request.getRequestDispatcher("hello.html"); rs.forward(request,response);
- 4. Example of RequestDispatcher interface In this example, we are validating the password entered by the user. If password is servlet, it will forward the request to the WelcomeServlet, otherwise will show an error message: sorry username or password error!. In this program, we are cheking for hardcoded information. But you can check it to the database also that we will see in the development chapter. In this example, we have created following files: index.html file: for getting input from the user. Login.java file: a servlet class for processing the response. If password is servet, it will forward the request to the welcome servlet. WelcomeServlet.java file: a servlet class for displaying the welcome message. web.xml file: a deployment descriptor file that contains the information about the servlet.
- 6. index.html <form action="servlet1" method="post"> Name:<input type="text" name="userName"/><br/> Password:<input type="password" name="userPass"/><br/> <input type="submit" value="login"/> </form>
- 7. WelcomeServlet.java import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class WelcomeServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String n=request.getParameter("userName"); out.print("Welcome "+n); } }
- 8. Login.java import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class Login extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String n=request.getParameter("userName"); String p=request.getParameter("userPass"); if(p.equals("servlet"){ RequestDispatcher rd=request.getRequestDispatcher("servlet2"); rd.forward(request, response); } else{ out.print("Sorry UserName or Password Error!"); RequestDispatcher rd=request.getRequestDispatcher("/index.html"); rd.include(request, response); } } }
- 12. THANK YOU