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Java(Java_Servlet_programs_examples).pdf
- 1. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Java Servlets
Example 1:
Index.html
<html><body>
<form action="welcome" method="get">
<input type="submit" value="Press to Run Servlet">
</form>
</body></html>
First.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class First extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
{
// Set response content type
res.setContentType("text/html");
// Actual logic goes here.
PrintWriter pw=res.getWriter();
pw.println("<h1>Welcome</h1>Welcome to Java Servlet.");
}
}
Web.xml
<web-app>
<servlet>
<servlet-name>wel</servlet-name>
<servlet-class>First</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>wel</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>
- 2. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 2:
Index.html
<html><body>
<form action="User" method="get">
Enter your name<input type="text" name="name"><br>
<input type="submit" value="login">
</form>
</body></html>
Username.java
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
public class Username extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
{
res.setContentType("text/html");
PrintWriter pw=res.getWriter();
String name=req.getParameter("name");
pw.println("Welcome "+name);
}
}
Web.xml
<web-app>
<servlet>
<servlet-name>Login</servlet-name>
<servlet-class>Username</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Login</servlet-name>
<url-pattern>/User</url-pattern>
</servlet-mapping>
</web-app>
- 3. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 3:
Index.html
<html><body>
<form action="Hello" method="get">
<input type="submit" Value="Load Servlet Hello !">
</form>
</body></html>
HelloWorld.java
// Import required java libraries
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
// Extend HttpServlet class
public class HelloWorld extends HttpServlet {
private String message;
public void init() throws ServletException {
// Do required initialization
message = "Hello World";
}
public void doGet(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException {
// Set response content type
res.setContentType("text/html");
// Actual logic goes here.
PrintWriter out = res.getWriter();
out.println("<h1>" + message + "</h1>");
}
public void destroy() {
// do nothing.
}
}
web.xml
<web-app>
<servlet>
<servlet-name>myHello</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myHello</servlet-name>
<url-pattern>/Hello</url-pattern>
</servlet-mapping>
</web-app>
- 4. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 4:
Index.html
<html><body>
<form action="Form" method="get">
<lable>First Name <input type="text" name="first_name"><br>
<lable>Last Name <input type="text" name="last_name"><br>
<input type="submit" Value="Submit">
</form>
</body></html>
HelloWorld.java
// Import required java libraries
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
// Extend HttpServlet class
public class HelloForm extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Using GET Method to Read Form Data";
out.println("<html>n");
out.println("<head><title>" + title + "</title></head>n");
out.println("<body bgcolor = "#f0f0f0">n");
out.println("<h1 align = "center">" + title + "</h1>n");
out.println("<ul>n");
out.println("<li><b>First Name</b>: "+request.getParameter("first_name"));
out.println("n");
out.println("<li><b>Last Name</b>: "+request.getParameter("last_name"));
out.println("n");
out.println("</ul>n");
out.println("</body>");
out.println("</html>");
}
}
- 5. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 5:
Index.html
<html><body>
<form action="Form" method="Post">
<lable>First Name <input type="text" name="first_name"><br>
<lable>Last Name <input type="text" name="last_name"><br>
<input type="submit" Value="Submit">
</form>
</body></html>
HelloWorld.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloForm extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Using GET Method to Read Form Data";
out.println("<html>n");
out.println("<head><title>" + title + "</title></head>n");
out.println("<body bgcolor = "#f0f0f0">n");
out.println("<h1 align = "center">" + title + "</h1>n");
out.println("<ul>n");
out.println("<li><b>First Name</b>: "+request.getParameter("first_name"));
out.println("n");
out.println("<li><b>Last Name</b>: "+request.getParameter("last_name"));
out.println("n");
out.println("</ul>n");
out.println("</body>");
out.println("</html>");
}
// Method to handle POST method request.
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
doGet(request, response);
}
}
- 6. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 6:
Index.html
<html>
<body>
<form action = "CheckBox" method = "POST" target = "_blank">
<input type = "checkbox" name = "maths" checked = "checked" /> Maths
<input type = "checkbox" name = "physics" /> Physics
<input type = "checkbox" name = "chemistry" checked = "checked" /> Chemistry
<input type = "submit" value = "Select Subject" />
</form>
</body>
</html>
CheckBox.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class CheckBox extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Reading Checkbox Data";
out.println("<html>");
out.println("<head><title>" + title + "</title></head>");
out.println("<body bgcolor = "#f0f0f0">");
out.println("<h1 align = "center">" + title + "</h1>");
out.println("<ul>");
out.println("<li><b>Maths Flag : </b>: " + request.getParameter("maths"));
out.println("<li><b>Physics Flag: </b>: "+ request.getParameter("physics"));
out.println("<li><b>Chemistry Flag: </b>: "+ request.getParameter("chemistry"));
out.println("</ul>");
out.println("</body>");
out.println("</html>");
}
// Method to handle POST method request.
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
doGet(request, response);
}
}
web.xml
<web-app>
<servlet>
<servlet-name>myForm</servlet-name>
<servlet-class>CheckBox</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myForm</servlet-name>
<url-pattern>/CheckBox</url-pattern>
</servlet-mapping>
</web-app>
- 7. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 7:
CheckBox.java
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class ReadParams extends HttpServlet {
// Method to handle GET method request.
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String title = "Reading All Form Parameters";
out.println("<html>");
out.println("<head><title>" + title + "</title></head>");
out.println("<body bgcolor = "#f0f0f0">n");
out.println("<h1 align = "center">" + title + "</h1>");
out.println("<table width = "100%" border = "1" align = "center">");
out.println("<tr bgcolor = "#949494">");
out.println("<th>Subject Name</th>");
out.println("<th>Subject Value(s)</th></tr>");
String [] Subject = request.getParameterValues("sub");
// Read multiple valued data
out.println("<tr><td><ul>");
for(String s : Subject) {
out.println("<li>" + s + "</li>");
}
out.println("</ul></td><td>Checked</td>");
out.println("</tr></table>n</body></html>");
}
// Method to handle POST method request.
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
doGet(request, response);
}
}
- 8. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 8:
Index.html
<html>
<body>
<form method="POST" ACTION = "firstservlet" NAME="myForm">
<h2> Enter your name</h2>
<INPUT TYPE="text" name="name"/>
<br/>
<h2> Salary</h2>
<INPUT TYPE="text" name="salary"/>
<BR/><BR/>
<INPUT type="submit" value="Submit"/>
</form>
</body>
</html>
web.xml
<web-app>
<servlet>
<servlet-name>myFirstServlet</servlet-name>
<servlet-class>FirstServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>mySecondServlet</servlet-name>
<servlet-class>SecondServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myFirstServlet</servlet-name>
<url-pattern>/firstservlet</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>mySecondServlet</servlet-name>
<url-pattern>/secondservlet</url-pattern>
</servlet-mapping>
</web-app>
- 9. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
FirstServlet.java
import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class FirstServlet extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String salary = request.getParameter("salary");
int sal = Integer.parseInt(salary);
int tax = (int)(sal * 0.15);
// converting tax into string
String taxValue = tax + "";
// request object can store values in the key-value form, later it
// can be retrieved by using getAttribute() method
request.setAttribute("tax", taxValue);
// getting object of servletContext
ServletContext sContext = getServletContext();
// getting object of a request dispatcher
RequestDispatcher rd = sContext.getRequestDispatcher("/secondservlet");
// calling forward method of request dispatcher
rd.forward(request, response);
}
// This method is calling processRequest()
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
// This method is calling processRequest()
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
Continue…
- 10. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
SecondServlet.java
import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class SecondServlet extends HttpServlet {
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
// obtaining values of name and salary text fields of index.html
String name = request.getParameter("name");
String salary = request.getParameter("salary");
/* getting attribute value that has been set by the calling servlet i.e. FirstServlet */
String tax = (String)request.getAttribute("tax");
// generating HTML tags using PrintWriter
out.println("<html>");
out.println("<head>");
out.println("<title>SecondServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1> Welcome " + name+ "</h1>");
out.println("<h3> Salary " + salary+ "</h3>");
out.println("<h3> Tax " + tax+ "</h3>");
out.println("</body>");
out.println("</html>");
out.close();
}
// This method is calling processRequest()
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
// This method is calling processRequest()
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
}
- 11. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
Example 9:
login.html
<html><body>
<h2> Please provide login details</h2>
<FORM METHOD="POST" ACTION="myForm" NAME="myForm" >
<BR> User Id:
<INPUT TYPE="text" name="userid"/>
<BR> Password:
<INPUT TYPE="password" name="pwd"/>
<BR> <BR>
<input type="submit" value="Submit Form"/>
</form>
</body></html>
register.html
<html><body>
<h2>Your login is incorrect. Please register yourself</h2>
<FORM METHOD="POST" ACTION="welcome2.html" NAME="myForm">
<BR> Name:
<INPUT TYPE="text" NAME="userid"/>
<BR> Address:
<INPUT TYPE="text" NAME="address"/>
<BR> Phone No:
<INPUT TYPE="text" NAME="phoneno"/>
<BR> <BR>
<input type="submit" value="Register"/>
</FORM>
</body></html>
welcome.html
<html><body>
<h2> You have successfully logged in </h2>
</body></html>
Welcome2.html
<html><body>
<h2> You have successfully Registered </h2>
</body></html>
- 12. Java Servlets BSIT-Sem-5th
Web Technologies
Prof. Usman Ahmad, Govt. Islamia Graduate College, Gujranwala.
MyServlet.java
import java.io.*;
import java.net.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException{
processRequest(request, response);
}
// Handles the HTTP POST request type
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
}
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String id = request.getParameter("userid");
String pwd = request.getParameter("pwd");
boolean b=id.equals("ali") && pwd.equals("123");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title> Login Detail</title></head>");
out.println("<body bgcolor = "#f0f0f0">");
out.println("<h1 align = "center">" + b +"</h1>");
out.println("</body>");
out.println("</html>");
// comparing id & password with fix values
if(id.equals("ali") && pwd.equals("123")) {
// redirectign user to welcome.html response.sendRedirect("welcome.html");
}
else {
// redirecting user to register.html
response.sendRedirect("register.html");
}
}
}
