In this tutorial you will learn about the Servlet URL Rewriting and its application with practical example.
Servlet URL Rewriting
Using the url rewriting we can append parameter in url and can send our data to next servlet. We send the parameter in key-value pair. It works even cookie is disabled but it works only with links.
The format will be like below code:
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https://www.w3adda.com?name=w3adda.com&data=servlet |
here name is key and w3adda.com is value.
Example:-
Let’s understand it by an simple example.
index.html
This will be our welcome file. Check below code.
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<html> <head> <title>W3adda.com</title> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> </head> <body> <form action="First"> Name:<input type="text" name="userName"/><br/> <input type="submit" value="go"/> </form> </body> </html> |
First.java
From this servlet class we will append our parameter in url. Check below code.
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package UrlRewriting; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class First extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); try{ response.setContentType("text/html"); PrintWriter out = response.getWriter(); String n=request.getParameter("userName"); out.print("Welcome to w3adda.com :"+n); //appending the username in the query string out.print("<a href='Second?uname="+n+"'>visit</a>"); out.close(); }catch(Exception e){System.out.println(e);} } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
Second.java
Here we will get parameter of given url. Check below code.
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package UrlRewriting; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class Second extends HttpServlet { /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> * methods. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ protected void processRequest(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=UTF-8"); } // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code."> /** * Handles the HTTP <code>GET</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); try{ response.setContentType("text/html"); PrintWriter out = response.getWriter(); //getting value from the query string String n=request.getParameter("uname"); out.print("Welcome to w3adda.com "+n); out.close(); }catch(Exception e){System.out.println(e);} } /** * Handles the HTTP <code>POST</code> method. * * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); } /** * Returns a short description of the servlet. * * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> } |
Output:-
The below images will show output of this code.
Screen 1:-
This is our index.html file output.
Screen 2:-
Below image is our First.java file output.
Screen 3:-
In the Second servlet file we will get this parameter by the request.getParameter() method. Check below image.
