ServletRequest and ServletResponse
1.MyServlet.java
import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
/**
*
* @author Arun Udayasuiyan
*/
public class MyServlet extends HttpServlet {
protected void doPOST(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
response.setContentType("text/html;charset=UTF-8");
try (PrintWriter out = response.getWriter()) {
String user = request.getParameter("user");
out.println("<h2> Welcome to PU "+user+"</h2>");
}
}
}
2. Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="6.0" xmlns="https://jakarta.ee/xml/ns/jakartaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd">
<servlet>
<servlet-name>check</servlet-name>
<servlet-class>MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>check</servlet-name>
<url-pattern>/check</url-pattern>
</servlet-mapping>
</web-app>
3. Index.html
<html>
<form method="post" action="check">
Name <input type="text" name="user" >
<input type="submit" value="submit">
</form>
</html>
sendRedirect()
1. index.html
<html>
<head>
<title> Send Redirect</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<form action="MyServlet">
<div align="center">
<input type="submit" value="Go to My Vlog">
</div>
</form>
</body>
</html>
MyServlet.java
import java.io.*;
import jakarta.servlet.*;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
public class MyServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
response.sendRedirect("https://www.youtube.com/@DigitalTamilAruvi");
}
finally {
out.close();
}
}
}
Output
RequestDispatcher Interface
1.index.html
<html>
<head>
<title>TODO supply a title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<form method="post" action="Validate">
Name:<input type="text" name="user" /><br/>
Password:<input type="password" name="pass" ><br/>
<input type="submit" value="submit">
</form>
</body>
</html>
2. Validate.java
import jakarta.servlet.RequestDispatcher;
import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
/**
*
* @author hp
*/
public class Validate extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
String name = request.getParameter("user");
String password = request.getParameter("pass");
if(password.equals("au"))
{
RequestDispatcher rd = request.getRequestDispatcher("Welcome");
rd.forward(request, response);
}
else
{
out.println("<font color='red'><b>You have entered incorrect password</b></font>");
RequestDispatcher rd = request.getRequestDispatcher("index.html");
rd.include(request, response);
}
}
finally {
out.close();
}
}
}
3.Welcome.java
import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
/**
*
* @author hp
*/
public class Welcome 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 doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
out.println("<h2>Welcome user</h2>");
}
finally {
out.close();
}
}
}
Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="6.0" xmlns="https://jakarta.ee/xml/ns/jakartaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd">
<servlet>
<servlet-name>Validate</servlet-name>
<servlet-class>Validate</servlet-class>
</servlet>
<servlet>
<servlet-name>Welcome</servlet-name>
<servlet-class>Welcome</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Validate</servlet-name>
<url-pattern>/Validate</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Welcome</servlet-name>
<url-pattern>/Welcome</url-pattern>
</servlet-mapping>
</web-app>
Output
ServletConfig
<html>
<head>
<title>TODO supply a title</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
<form action="MyServlet_config">
<div align="center">
<input type="submit" value="Servlet Config">
</div>
</form>
</body>
</html>
2. MyServlet_config.java
import jakarta.servlet.ServletConfig;
import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
/**
*
* @author hp
*/
public class MyServlet_config extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
ServletConfig sc = getServletConfig();
out.println(sc.getInitParameter("email"));
}
}
3. Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="6.0" xmlns="https://jakarta.ee/xml/ns/jakartaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_6_0.xsd">
<servlet>
<servlet-name>MyServlet_config</servlet-name>
<servlet-class>MyServlet_config</servlet-class>
<init-param>
<param-name>email</param-name>
<param-value>arunu@dtech.com</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet_config</servlet-name>
<url-pattern>/MyServlet_config</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>
output
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