jsp: how to get value from session? - java

I get an String array from session and I want to show the String from the array.
I know javascript can't get data from session directly. Is there any method I can get the data from session and transfer it to javascrip?
My code as follows:
<%# page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<%String[] sele = (String[])session.getAttribute("selections");%>;
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<meta http-equiv="Expires" content="0">
<meta http-equiv="kiben" content="no-cache">
<title>Check List</title>
<script language="javascript" type="text/JavaScript" src="cookie.js">
</script>
<script text="text/javascript">
{
var selections = //String array form session
for(var v=0;v<selections.length;v++){
fillForm(selections[v]);
}
}
function fillForm(name){
var checkbox= document.createElement("input");
checkbox.type="checkbox";
checkbox.name=name;
checkbox.value=name;
checkbox.id=name;
var label = document.createElement("label");
label.htmlFor="id";
label.appendChild(document.createTextNode(name));
var container = document.getElementById("checklist");
container.appendChild(checkbox);
container.appendChild(label);
container.appendChild(document.createElement("br"));
}
function submitAction(){
addUserName(document.getElementById("checklist"));
var elem = document.getElementById("checklist").elements;
for(i =0;i<elem.length;i++){
elem[i].checked = true;
}
var form = document.getElementById("checklist");
form.submit();
}
</script>
</head>
<body>
<form id="checklist" action="selection">
</form>
<Button type="button" onclick="submitAction()" name="submit">Submit</button>
</body>
</html>

Simply use JSP Expression Language and JSP JSTL
<script>
alert("value: ${selections}");
</script>
Here selections is an attribute that is set in any scope page, request, session or application.
You can directly access an attribute form session scope:
{sessionScope.selections}
Note: I don't know that Java ArrayList does work in JavaScript as well. If it doesn't work then simply set a comma separated string as session attribute and split it in JavaScript as shown below.
Sample code:
<script>
var selections = "${sessionScope.csv}".split(",");
for ( var v = 0; v < selections.length; v++) {
alert(selections[v]);
}
</script>
Here csv is a comma separated string value that is set in session scope.
Use JSP JSTL and EL instead of Scriplet that is more easy to use and less error prone.
You can achieve it in JSTL without using JavaScript. Simply iterate the list using <c:forEach> tag and add that much of check boxes and labels.
Sample code:
<%# taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
...
<body>
...
<c:forEach items="${selections }" var="name">
<input type="checkbox" name="${name}" value="${name}" id="${name}">
...
</c:forEach>
</body>

Related

Enumeration<> Enumeration difference

I'm a biginner in JSP and I'm confused about the difference between
Enumeration and Enumeration<type>
I'm learning with this Korean book and the example source in it says Enumeration
with the eclipse neon version it doesn't work. It works only when it write
Enumeration<String>. Can someone tell me the difference?
<%#page import="java.util.Enumeration"%>
<%# page language="java" contentType="text/html;
charset=UTF-8"pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>헤더 목록 출력</title>
</head>
<body>
<%
Enumeration<String> headerEnum = request.getHeaderNames();
while(headerEnum.hasMoreElements()){
String headerName = (String)headerEnum.nextElement();
String headerValue = request.getHeader(headerName);
%>
<%=headerName %> = <%=headerValue %> <br>
<%
}
%>
</body>
</html>
Just give it a look at the Enumeration documentation. Also review the generic types documentation.
By usingEnumeration you are using Enumeration<Object> as it is the default. What this <Object> does is just indicate the Enumeration class that in that particular instance, the type that it calls E (in the Enumeration Documentation) will be resolved to Object. By using <String> happens the same: the type called E will be resolved to String.
If you check the nextElement() signature it returns E. So, by using Enumeration or Enumeration<Object> that method will return Object and you will need the cast you did:
String headerName = (String)headerEnum.nextElement();
By using Enumeration<String> the method will return an String, so you can directly do this:
String headerName = headerEnum.nextElement();

Unable to decode utf-8 using thai language?

This is my JSP page:
<%--
Document : new jsp1
Created on : Nov 24, 2014, 12:38:07 PM
Author : Java
--%>
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<%
String msg="206_John_help i m in trouble,delhi,อินเดีย_30.64741430_76.817313799";
String result = java.net.URLEncoder.encode(msg, "UTF-8");
System.out.println("The msg is "+result);
String result1=java.net.URLDecoder.decode(result, "UTF-8");
System.out.println("The decoded msg is "+result1);
%>
</body>
</html>
The output is 206_John_help i m in trouble,delhi,???????_30.64741430_76.817313799
I am always getting ?????? instead of thai alphabets. How can I get the Thai alphabets while decoding?
The problem is not on encoding and decoding the messages but in the server container. Seems that server cant display properly the special characters, so it can not treat them from request.
If you display the values in the JSP page itself, everything is working fine.
Example:
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<%
String msg="206_John_help i m in trouble,delhi,อินเดีย_30.64741430_76.817313799";
System.out.println("The original message "+msg);
String result = java.net.URLEncoder.encode(msg, "UTF-8");
System.out.println("The msg is "+result);
String result1=java.net.URLDecoder.decode(result, "UTF-8");
System.out.println("The decoded msg is "+result1);
%>
Original message <%=msg %><br />
Encrypted message <%=result %> <br />
Decrypted message <%=result1 %>
</body>
</html>

How to use jsp variable in javascript array?

Hi I have a jsp page where I have some variable. I want to access the variable in a javascript array. How can I get this?
Demo.jsp
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<%
int i=1;
int j=2;
int k=3;
int l=4;
%>
</body>
</html>
I want to use these 4 variables in the javascript array and print them.
How can I achieve this?
Try,
<script language="JavaScript">
var Arr = new Array();
Arr[0] = '<%=i %>';
Arr[1] = '<%=j %>';
Arr[2] = '<%=k %>';
Arr[3] = '<%=l %>';
</script>
In Java script you have to use scriplet tag to use jsp data.
<%
Integet a = i ; //here i is your jsp variable
%>
In order to make this work you should declare the variable before using it (as always):
<%
String myVar="blabla";
%>
<script type="text/javascript">
foo();
function foo() {
var value = "<%=myVar%>";
alert(value);
}
</script>
Or :
var result = [];
result.push(<%i%>);
result.push(<%j%>);
result.push(<%k%>);
result.push(<%l%>);
You can access it using JSTL.
set java variable to JSTL variable
Access it in Java script as
var x='${jstl_varialbe_goes_here
}';
alert(x);

passing the value of an array to a method in javascript

I have to create an HTML table in which I will have images to display. further I want to pass this path to the next servlet page. for this I have created a separate method in javascript. Now the problem is this, whenever I click on any image it passes the same path everytime. please give me any solutions for this problem or tell me any alternate of passing the path to next page.
my code is--->
<%#page import = "java.util.*" %>
<%#taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%#taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<html>
<head>
<link href="Style.css" rel="stylesheet" type="text/css"/>
<title>Home</title>
</head>
<body>
<center>
<h3>${requestScope.payment}</h3>
<jsp:include page="Header.jsp"/>
<jsp:include page="Menu2.jsp"></jsp:include>
<form method="post" action="ProductFeatures" id="myform">
<table border="1" bordercolor="green" bgcolor="yellow" align="center" id="store" >
</table>
</form>
<%
ArrayList<String> l = null;
if(request.getAttribute("list") instanceof ArrayList<?>){
l = (ArrayList<String>)request.getAttribute("list");
}
%>
<script type="text/javascript">
window.onload = function(){
var path = new Array();
var imagepath = new Array();
var table = document.getElementById("store");
var j=0;
var k=0;
var row = null;
<%for(int i=0;i<l.size();i++) {%>
path.push("<%=l.get(i)%>");
<%}%>
for(i=0;i<path.length;i++){
imagepath[i] =path[i].replace ("F:java_projectsApplication4images","F:\\java_projects\\Application4\\images\\");
}
for(i=0;i<path.length;i++){
if(i%4==0){
row = table.insertRow(j);
k=0;
j++;
}
var data = imagepath[i];
var cell = row.insertCell(k);
var image = document.createElement("img");
image.setAttribute("src",imagepath[i]);
image.setAttribute("height","160");
image.setAttribute("width","120");
image.setAttribute("onclick",function(){getDetails(data);});
cell.appendChild(image);
row.appendChild(cell);
k++;
}
};
function getDetails(imagepath){
document.write(imagepath);
if(path.length>10){
var form = document.getElementById("myform");
var input = document.createElement("input");
input.type="hidden";
input.value=imagepath;
input.name="imagepath";
form.appendChild(input);
form.submit();
}
}
</script>
<jsp:include page="Footer.jsp"/>
</center>
</body>
</html>
Here in this code in function getDetails variable imagepath always contains the same value. please somebody tell me wheres the bug in this code. I am not getting it properly.
Change the following line:
image.setAttribute("onclick",function(){getDetails(data);});
into:
image.setAttribute("onclick",(function(d){return function(){getDetails(d);}}(data));
Also, the line:
row.appendChild(cell);
is redondant because the cell was inserted with row.insertCell(k)

JSP - Get score from a jsp quiz application

Hi I'm creating a quiz application in jsp and am using different jsp pages for every question. I'd like to keep a score after each question is answered. My problem is that I'm picking random answers from a database, within which lies the correct answer too. Since I can't guess which letter the correct answer will appear on, could you suggest what I should do? I am posting the first and second question jsp's to give you an idea of how I'm doing it:
q1.jsp
<%#page import="java.util.Random"%>
<%#page import="java.util.ArrayList"%>
<%#page import="org.me.jsp.beans.WordBean"%>
<%#page import="java.util.List"%>
<!--This JSP acts as the first question in a multiple choice quiz, with the user
asked to submit their answer to the question-->
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<jsp:useBean id = "wordData" scope = "request"
class = "org.me.jsp.beans.WordDataBean" />
<html>
<head>
<title>Big Java Quiz, question 1</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<%if (request.getParameter("choice").equals("N")) {
out.print("<meta http-equiv='refresh' content='0;url=options.jsp'/>");
}
//Redirects user back to index if they did not want to take quiz%>
<form action="q2.jsp" method="POST">
<%
List<WordBean> wordList = wordData.getWordList();
List<String> answersList = new ArrayList<String>();
Random random = new Random();
Random forAnswers = new Random();
WordBean goodOne = wordList.get(random.nextInt(wordList.size()));
//take it out from the list
wordList.remove(goodOne);
//add it to the answers list
answersList.add(goodOne.getGermanName());
WordBean fakeOne = wordList.get(random.nextInt(wordList.size()));
//take it out from the list
wordList.remove(fakeOne);
//add it to the answers list
answersList.add(fakeOne.getGermanName());
WordBean fakeTwo = wordList.get(random.nextInt(wordList.size()));
//take it out from the list
wordList.remove(fakeTwo);
//add it to the answers list
answersList.add(fakeTwo.getGermanName());
%>What is the English word for the German word <%=goodOne.getEnglishName()%>?<br>
<%
char letter = 'A';
for (String answer : answersList) {
%>
<input type="radio" name="q1Answer" value=""/><label for="<%=letter%>"><%=letter%>)<%=answersList.get(forAnswers.nextInt(3))%> />
<% //point to the next letter
letter++;
}
%>
<input type="submit" value="Submit"/>
</form>
</body>
</html>
q2.jsp
<%--
Document : q2
Created on : 06-May-2012, 18:54:32
Author : encore
--%>
<!--This JSP acts as the second question in a multiple choice quiz, with the user
asked to submit their answer to the question-->
<?xml version = "1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Big Java Quiz, question 2</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<%int score = 0;
if(request.getParameter("q1Answer").equals("C"))
score++; //Increments score if answer submitted was correct%>
<form action="q3.jsp" method="POST">
Your current score is: <%out.print(score);%>/20
<input type="hidden" name="q2Score" value="<%out.print(score);%>"/>
<!--Hidden button allows score to be accessed by next JSP-->
<b>Question 2.</b> When an exception is generated it is said to have been _________?<br/><br/>
<input type="radio" name="q2Answer" value="A"/><label for="A">A) Built</label><br/>
<input type="radio" name="q2Answer" value="B"/><label for="B">B) Thrown</label><br/>
<input type="radio" name="q2Answer" value="C"/><label for="C">C) Caught</label><br/>
<input type="radio" name="q2Answer" value="D"/><label for="D">D) Detected</label><br/><br/>
<input type="submit" value="Submit"/>
</form>
</body>
</html>
Note: the form of the second question will obviously be changed to something else, currently I'm concentrating on getting the score .
In the page for Q1, where you should know the correct answer, put it in the session and then retrieve it in the next page.

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