Accessing Map attached to Servlet using JSP Expression Language and JSTL Tag Library

 

 Servlet Code:

java

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class ServletExpression extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {

        response.setContentType("text/html;charset=UTF-8");

        // Prepare data
        ArrayList<String> instituteList = new ArrayList<>();
        instituteList.add("Institute-1");
        instituteList.add("Institute-2");
        instituteList.add("Institute-3");
        instituteList.add("Institute-4");

        Map<String, Integer> accountMap = new HashMap<>();
        accountMap.put("abc", 200000);
        accountMap.put("xyz", 100000);
        accountMap.put("pqr", 300000);
        accountMap.put("lmn", 400000);

        // Store in session
        HttpSession session = request.getSession();
        session.setAttribute("instname", instituteList);

        // Store in application scope
        ServletContext application = request.getServletContext();
        application.setAttribute("acctname", accountMap);

        // Output HTML
        try (PrintWriter out = response.getWriter()) {
            out.println("""
                <html>
                    <head>
                        <title>First Servlet</title>
                    </head>
                    <body>
                        <h1>Welcome to JAVA</h1>
                    </body>
                </html>
                """);
        }
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws IOException, ServletException {
        doPost(request, response);
    }
}

JSP (displayApplication.jsp)

jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<h2>JSTL Tag Example</h2>
<hr/>

<!-- Direct index access -->
1: ${instname[0]} <br/>
2: ${instname[1]} <br/>
3: ${instname[2]} <br/>
4: <c:out value="${instname[3]}" default="Institute-1"/> <br/>
5: <c:out value="${instname[4]}" default="Institute-2"/> <br/>
6: <c:out value="${instname[5]}" default="Institute-3"/> <br/>

<hr/>

<b>Using JSTL to iterate ArrayList:</b><br/><br/>

<c:forEach var="item" items="${instname}">
    ${item} <br/>
</c:forEach>

<hr/>

<b>&lt;c:forEach&gt; examples:</b><br/>

<c:forEach var="i" begin="1" end="10">
    ${i}
    <c:if test="${i < 3}"> less than 3 </c:if>
    <c:if test="${i < 6}"> less than 6 </c:if>
    <c:if test="${i < 8}"> less than 8 </c:if>
    <br/>
</c:forEach>

<hr/>

<b>&lt;c:choose&gt; example:</b><br/>

<c:forEach var="i" begin="1" end="10">
    ${i}
    <c:choose>
        <c:when test="${i < 3}"> less than 3 </c:when>
        <c:when test="${i < 6}"> less than 6 </c:when>
        <c:when test="${i < 8}"> less than 8 </c:when>
        <c:when test="${i == 8}"> equal to 8 </c:when>
        <c:otherwise> greater than 8 </c:otherwise>
    </c:choose>
    <br/>
</c:forEach>

<hr/>

<b>HashMap example:</b><br/>

<c:forEach var="entry" items="${acctname}">
    ${entry.key} has account balance US $ ${entry.value} <br/>
</c:forEach>

<hr/>

<b>Reverse Order Print:</b><br/>

<c:forEach var="i" begin="1" end="10" step="2">
    <c:set var="revorder" value="${11 - i}" />
    ${revorder} <br/>
</c:forEach>

<hr/>

Accessing ArrayList , HashMap attached to Servlet using JSP Expression Language and JSTL Tag Library

/ **
Servlet class in which ArrayList and HashMap is created and attached to ServletContext Object

*/

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;


public class ServletExpression extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
    response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("<html> <head> <title> First Servlet ... </title></head>");
out.println("<body> <h1> Welcome to JAVA  </h1>");

ArrayList<String> alist = new ArrayList<String>();

alist.add("ISTAR");  alist.add("ADIT");
alist.add("VPSCI");  alist.add("NVPAS");

HttpSession session = request.getSession();
session.setAttribute("instname" ,alist);


//Setting hashmap in Application

HashMap acnt = new HashMap();

acnt.put("abc",200000);
acnt.put("xyz",100000);
acnt.put("pqr",300000);
acnt.put("lmn",400000);

ServletContext application = request.getServletContext();

application.setAttribute("acctname",acnt);

out.println("</body></html>" );
 
  }  //end of method
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
doPost(request, response);
  }  //end of doGet method


}




2) Accessing ArrayList and HashMap elements in JSP Page (displayApplication.jsp):


<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<c:out value="JSTL Tag Example" />

<hr/>
1:
${instname[0]} <br/>
2:
${instname[1]} <br/>
3:
${instname[2]} <br/>
4: <c:out value="${instname[3]}" default="ISTAR" /> <br/>
5: <c:out value="${instname[4]}" default="ISTAR" /> <br/>
6: <c:out value="${instname[5]}" default="ISTAR" /> <br/>


<hr/>
<b>Using JSTL , accessing ArrayList values::: </b><br/><br/>

<c:forEach var="i" items="${instname}" >

${i} <br/>
</c:forEach>

 <hr/>
 <b>
 <c:out value="<c:forEach> examples ::" /> </b>
 <br/>
 <c:forEach var="i" begin="1" end="10" >

${i}
<c:if test="${i<3}"> less than 3 </c:if>
<c:if test="${i<6}"> less than 6 </c:if>
<c:if test="${i<8}"> less than 8 </c:if>
<br/>
 </c:forEach>

 <hr/> <br/>

 <b>
 <c:out value="<c:choose> example:::" /> </b><br/>

 <c:forEach var="i" begin="1" end="10" >

${i}
<c:choose>
<c:when test="${i<3}"> less than 3 </c:when>
<c:when test="${i<6}"> less than 6 </c:when>
<c:when test="${i<8}"> less than 8 </c:when>
<c:when test="${i==8}"> equal to 8 </c:when>
<c:otherwise> greater than 8 </c:otherwise>
</c:choose>
<br/>
</c:forEach>

 <hr/>

 <b> HashMap example :::</b>
 <br/>


<c:forEach var="i" items="${acctname}" >

${i.key} has account balance US \$ ${i.value} <br/>

</c:forEach>

 <hr />
 <b>
 Reverse Order print : </b>
 <br/>

 <c:forEach var="i" begin="1" end="10"  step="2">
 <c:set var="revorder" value="${11-i}" />
${revorder} <br/>
 </c:forEach>

 <hr/>

Creating Attribute at Request ,Session and Application in Servlet class

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import education.Student;

public class SessionApplicationDemo extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
    response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("<html> <head> <title> First Servlet ... </title></head>");
out.println("<body> <h1> Welcome to JAVA  </h1>");
out.println("Hello World <br>" );

Student student1 = new Student();
student1.setSid(2020);
student1.setSname("Hitesh");

Student student2 = new Student();
student2.setSid(3020);
student2.setSname("Nayan");
//access ServletContext

ServletContext application = request.getServletContext();

application.setAttribute("s2",student1);
//accessing application attribute
Student st1 = (Student) application.getAttribute("s2");

out.println(st1.getSid() +"<br/>");
out.println(st1.getSname());



//creating session

HttpSession session = request.getSession();

session.setAttribute("s3",student2);

/*request.setAttribute("s2",student1);
//accessing request attribute
Student st1 = (Student) request.getAttribute("s2");

out.println(st1.getSid() +"<br/>");
out.println(st1.getSname());
*/
//access session attribute
Student st2 = (Student) session.getAttribute("s3");

out.println(st2.getSid() +"<br/>");
out.println(st2.getSname());

out.println("</body></html>" );
 
  }  //end of method
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
doPost(request, response);
  }


}

Java Bean Example

//Student Bean class

package education;

public class Student {
private int sid;
private String sname;

public void setSid(int sid) {
this.sid = sid;
}
public void setSname(String sname) {
this.sname = sname;
}

public int getSid() { return sid; }

public String getSname() { return sname; }

}

_________________________________________________________________________________

JSP Pages 
1) inputform.jsp
 ________________________________________________________________________________

<html>

<body>
<form action="master.jsp" >
SID :
<input type="text" name="sidtest" /><br>
SNAME:
<input type="text" name="snametest" /> <br>
<input type="Submit" />

</form>
</body>

</html>
_________________________________________________________________________________
2 )  master.jsp
_________________________________________________________________________________

<html>


<body>

<hr/>

Main Page<br/>

<hr/>
Student Information :
<br/>
Using JavaBeans
<br/>
Student data:

<%--
here scope="session" or scope="request" or scope="application"
based on requirement where Student object is to be attached as attribute
 --%>


<jsp:useBean id="st1" class="education.Student" scope="application" />


<jsp:setProperty name="st1" property="sid" param="sidtest" />

<jsp:setProperty name="st1" property="sname" param="snametest"/>

ID:
<jsp:getProperty name="st1" property="sid" />
<br/>
NAME:
<jsp:getProperty name="st1" property="sname" />



<hr/>
<jsp:include page="WEB-INF/jsp/displayrequest.jsp" />

</body>

</html>
________________________________________________________________________________

3. ) displayrequest.jsp
________________________________________________________________________________

<hr/>

Included page
<br/>
<br/>
<jsp:useBean id="st1" class="education.Student" scope="request" />


SID:<jsp:getProperty name="st1" property="sid" />
<br/>
NAME:
<jsp:getProperty name="st1" property="sname" />

________________________________________________________________________________
4. ) displaysession.jsp
________________________________________________________________________________

<hr/>
Session Page
<br/>
<jsp:useBean id="st1" class="education.Student" scope="session" />


SID:<jsp:getProperty name="st1" property="sid" />
<br/>
NAME:
<jsp:getProperty name="st1" property="sname" />

________________________________________________________________________________
5. ) displayapplication.jsp
________________________________________________________________________________

<hr/>
Application Page

<br/>

<jsp:useBean id="st1" class="education.Student" scope="application" />


SID:<jsp:getProperty name="st1" property="sid" />
<br/>
NAME:
<jsp:getProperty name="st1" property="sname" />

Generating output in html or in excel format based on user input

1) HTML Input File :


<html>
<body>

<form  action="readdata" method="get" >
<fieldset>

<br/>
<b> Do you want Request Header Data? ( in Html or Excel)" : </b>
<input type="radio" name="doctype" value="html" checked /> Html
<input type="radio" name="doctype" value="excel" /> Excel
<br/>
<input type="submit" />
</fieldset>
</form>

</body>

2) Servlet that generate dynamic content (in html or in excel format ) based on user input :

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.util.Enumeration;

public class ServletReadData extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {

   

String sdoctype = request.getParameter("doctype");

if (sdoctype.equals("html")) {

response.setContentType("text/html"); }

else if (sdoctype.equals("excel") )

{ response.setContentType("application/vnd.ms-excel"); }

   

PrintWriter out = response.getWriter();

out.println("<html> <head> <title> First Servlet ... </title></head>");

out.println("<body> <h1> Java Servlet Request Header Reading.. </h1>");

       Enumeration myheader =request.getHeaderNames();

out.println( "<table border='2'> <tr> <th> Header Name </th><th> Header Values </th> </tr>");

while (myheader.hasMoreElements() )

{

String myhname =(String) myheader.nextElement();

//Header Name

out.println("<tr> <td>");

out.println( myhname);

out.println("</td>");

//values of header

Enumeration myhvalue = request.getHeaders(myhname);

out.println("<td>");

while (myhvalue.hasMoreElements() )

{

out.println(myhvalue.nextElement());

}

out.println("</td>");

out.println("</tr>");

}

out.println("</body></html>" );

  }  //end of doPost method

 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {

doPost(request, response);

  }  //end of doGet method

}

Servlet Reading HTTP Request Headers and values associated with each request header

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.Enumeration;

public class ServletReadData extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
    response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("<html> <head> <title> First Servlet ... </title></head>");
out.println("<body> <h1> Java Servlet Request Header Reading.. </h1>");

Enumeration myheader =request.getHeaderNames();

out.println( "<table border='2'> <tr> <th> Header Name </th><th> Header Values </th> </tr>");
while (myheader.hasMoreElements() )
{
String myhname =(String) myheader.nextElement();
//Header Name
out.println("<tr> <td>");
out.println( myhname);
out.println("</td>");
//values of header
Enumeration myhvalue = request.getHeaders(myhname);
out.println("<td>");
while (myhvalue.hasMoreElements() )
{
out.println(myhvalue.nextElement());
}
out.println("</td>");
out.println("</tr>");

}

out.println("</body></html>" );

  }  //end of doPost method

 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
doPost(request, response);
  }  //end of doGet method


} // end of class

_______________________________________________________________________________

The output of the Above Servlet Program:

Java Servlet Request Header Reading..

Header Name	Header Values
host	localhost:8080
connection	keep-alive
content-length	53
cache-control	max-age=0
accept	text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
origin	http://localhost:8080
user-agent	Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.111 Safari/537.36
content-type	application/x-www-form-urlencoded
referer	http://localhost:8080/awtad2015/callservlet.html
accept-encoding	gzip, deflate
accept-language	en-US,en;q=0.8

Servlet with getRequestParameter and getParameterValues methods and HTML Form example

1) HTML Form File 


<html>
<body>
<!--
<a href="http://localhost:8080/awtad2015/html/file.aspx"> ServletDemo </a>
-->

<form  action="readdata" method="post" >
<fieldset>
<legend> Institute Information </legend>
Institute Name :
<input type="text" name="iname" value="ISTAR"/> <br>
Place :
<input type="radio" name="place" value="City" checked />City &nbsp;
<input type="radio" name="place" value="Village"  /> Village&nbsp;
<input type="radio" name="place" value="Town"  />Town &nbsp;
<br>
<hr width="30%" align="left"/>
<input type="checkbox" name="course" value="MCA" checked />MCA &nbsp;
<input type="checkbox" name="course" value="MSc.(IT)" checked />MSc.(IT) &nbsp;
<input type="checkbox" name="course" value="MSc(Est)"  />MSc(EST) &nbsp;
<input type="submit" />
</fieldset>
</form>

</body>

</html>



2) Servlet Class:  ServletReadData 


import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class ServletReadData extends HttpServlet {

  public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
    response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("<html> <head> <title> First Servlet ... </title></head>");
out.println("<body> <h1> Welcome to JAVA  </h1>");


out.println("Hello World <br>" );

String siname = request.getParameter("iname");
String splace = request.getParameter("place");

out.println("Institute Name : "+ siname + "<br>");
out.println("Place Name : " + splace);
String courses[] = request.getParameterValues("course");
out.println("<br> Course Name : ");
for (String cname : courses)
{
out.println(cname + "<br>");
}


out.println("</body></html>" );

  }  //end of doPost method

 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException

  {
doPost(request, response);
  }  //end of doGet method


}



3) web.xml entry for ServletReadData

<web-app ...
>
....................

  <servlet>
      <servlet-name>ServletRead</servlet-name>
      <servlet-class>ServletReadData</servlet-class>
  </servlet>

    <servlet-mapping>
      <servlet-name>ServletRead</servlet-name>
      <url-pattern>/readdata</url-pattern>
    </servlet-mapping>
  .....
......
  </web-app>

MVC Architecture Example

LoginForm.html file :
-------------------------------------------------------------

<form method="post" action="/istar/ControllerServlet">
NAME :
<input type="text" name="lname" />  <br>
PASSWORD:
<input type="password" name="lpassword" /> <br>

<input type="submit" value="LOGIN" />
</form>
______________________________________________________________________________

ControllerServlet.java  file:
-----------------------------------------------------------------------------------------
package mymvc;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import mybean.LoginBean;
public class ControllerServlet extends HttpServlet
{
String forwardstr;
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException
{
doGet(request, response);
}

public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException
{
String uname = request.getParameter("lname");
String upassword = request.getParameter("lpassword");

LoginBean lbean = new LoginBean();
lbean.setUname(uname);
lbean.setUpassword(upassword);

request.setAttribute("lbean",lbean);

boolean valid = lbean.validate();
if (valid==true)
{
forwardstr = "/WEB-INF/classes/mybean/LoginSuccess.jsp";
RequestDispatcher rd = request.getRequestDispatcher(forwardstr);
rd.forward(request,response);
}
else
{
forwardstr= "/WEB-INF/classes/mybean/LoginFailure.jsp";
RequestDispatcher rd = request.getRequestDispatcher(forwardstr);
rd.forward(request,response);
}
}
}
________________________________________________________________________________
LoginBean.java file 
----------------------------------------------------------------------------------------------------------------------------
package mybean;
public class LoginBean
{
private String uname;
private String upassword;

public boolean validate()
{
if (upassword.equals("1234") && uname.equals("istar"))
return true;
else
return false;
}

public void setUname(String uname) {
this.uname= uname;
}

public void setUpassword(String upassword)  {
this.upassword = upassword;
}
public String getUname()  { return uname; }
}
________________________________________________________________________________
LoginSuccess.jsp file :
--------------------------------------------------------------
<html>
<body>
<h3>Login Successful....</h3> <br>
<jsp:useBean id="lbean" type="mybean.LoginBean" scope="request"/>

UserName is : <jsp:getProperty name="lbean" property="uname" />
</body>

</html>
________________________________________________________________________________

LoginFailure.jsp file :

-------------------------------------------------------------------------

<html>

<body>

Invalid UserName & Password !..<br>

Try Again.. <br>

<hr>

<%@include file="/mvc/LoginForm.html" %>

<body>

</html>

Java Bean Examples

Java Bean Class: Student.java
___________________________________________

package mydata;
public class Student {
 private int sid;
 private String sname;
 private double perct;

 public void setSid(int iid)
 {
   sid=iid;
 }
 public void setSname(String nm)
 {    sname=nm;  }

 public void setPerct(double pt)
 {     perct=pt;  }

 public int getSid() {   return sid; }
 public String getSname() { return sname; }
 public double getPerct() { return perct; }


}
_____________________________________________________________
 Bean Creation JSP Page Example 


Using JAVA BEAN :

<jsp:useBean id="s1" class="mydata.Student" />

<jsp:setProperty name="s1" property="sid" value='<%= Integer.parseInt(request.getParameter("sid"))%>' />
<jsp:setProperty name="s1" property="sname" value='<%= request.getParameter("sname")%>' />

<jsp:setProperty name="s1" property="perct" value='<%= Double.parseDouble(request.getParameter("perct"))%>' />


Using param attribute

<jsp:useBean id="s2" class="mydata.Student" scope="request" />

<jsp:setProperty name="s2" property="*"  />

<jsp:forward page="/WEB-INF/filedata/forwardbean.jsp" />

_______________________________________________________________________________
 Forwardbean.jsp example

Welcome to the ISTAR College

<h2> This is request forwarded page   </h2>

Here ..  Student information :

<jsp:useBean id="s2" class="mydata.Student"  scope="request" />


ID:<jsp:getProperty name="s2" property="sid" /><br>

Name: <jsp:getProperty name="s2" property="sname" /><br>

Percentage :<jsp:getProperty name="s2" property="perct" />

Web Technology & Application Development (Java Technology) EXAMPLE PROGRAMS

This blog is for my Gujarat Technological University Students to get prepared for MCA - Sem -4 subjects based on JAVA SERVLETS, JAVA SERVER PAGES(JSP), JAVA BEANS, JSP EXPRESSION LANGUAGE PROGRAMS, NOTES AND POWER POINT SLIDES ARE AVAILABLE HERE

---