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>