Retrieve values from a bean in JSP

[Maan Suraj]

Please Note: This Post is lengthy, but question is simple

I have added all these files for more clarity only. I have a section MyQuestion(please scroll down below) for the question

Iam trying to implement cookies for my application.
I have 3 files for the same. 1) A filter class, which intercepts every request 2) PCH class which has methods to handle cookie related things 3) PCD is a simple Java bean with getters and setters for all the fields, of which we want to create a cookie

Agenda
Create a Persistent cookie. Create only one cookie, with all fields separated by a , symbol. i.e if user enters from date and to date then the cookie will store <FD>,<td> i.e one single string.I implemented like this
1) MyFilter.java (intercepts every request).
//Has a reference to PCH. PCH is a singleton

import ..... 

public class MyFilter implements Filter {
	
	
	static PCH persistentCookieHandler;
	static {
	
		persistentCookieHandler = new PCH();
	}
	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		
		Cookie cookie;		
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse resp = (HttpServletResponse) response;
		// check for the HTTP header that
		// signifies GZIP support		
		persistentCookieHandler.createCookieData(req);		
		if (persistentCookieHandler.hasCookieChanged(req)) {
			cookie = new Cookie("singleCookie", persistentCookieHandler
					.getCookieString());
			cookie.setMaxAge(1000000);	
			persistentCookieHandler.updateCookieValues(resp, cookie);
		
		}
		filterChain.doFilter(request, response);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub

	}
	
}

2)PCH.java ( has methods for handling cookie related tasks)
//Above class has a reference to PCD. PCD is nothing but a Java Bean with all getters and setters for all fields creating cookie.
To handle multiple client requests,(for real time Scenarios),PCD is stored in a ThreadLocal .

public class PCH 
{
	
	Cookie cookie;
	
	// Define/create thread local variable
    static ThreadLocal<PCD> threadLocalForPCD = new ThreadLocal<PCD>();
	static ThreadLocal threadLocalForCookieString = new ThreadLocal();
	String fromDate="";
	String toDate="";
	String numberOfBooks="";
	PCD PCD;
	
	public void createCookieData(HttpServletRequest req)
	{
		if((null!=(fromDate=(String)req.getParameter("fromDate")))&&(null!=(toDate=(String)req.getParameter("toDate")))&&(null!=(numberOfBooks=(String)req.getParameter("numberofbooks"))))
				{
		PCD=new PCD();
		PCD.setfromDate(fromDate);
		PCD.settoDate(toDate);
		PCD.setnumberOfBooks((numberOfBooks));
		threadLocalForPCD.set(PCD);	
		
				}
		
	
	}
	
	public Boolean hasCookieChanged(HttpServletRequest req) 
	{
		boolean isCookieChanged=true;
		Cookie cookies[] = req.getCookies();
		String singleCookie=null;;
		if (cookies != null) {
			for (int i = 0; i < cookies.length; i++) {
				if (cookies[i].getName().equals("singleCookie")) {
					singleCookie=cookies[i].getValue();
					break;
				}
			}
		}
		String cookieFormatFromPCD=null;		
		cookieFormatFromPCD=getCookieString();
		if(((null!=cookieFormatFromPCD)&&(null!=singleCookie)&&((cookieFormatFromPCD.equals(singleCookie))))||(null==cookieFormatFromPCD))
		{
			isCookieChanged=false;
		}
			
		return isCookieChanged;
	}
	
	public void updateCookieValues(HttpServletResponse resp,Cookie singleCookie) 
	{
		setCookieValueChanged(true);		
		resp.addCookie(cookieFormat);
		
	}
	public String getCookieString()
	{
		PCD=threadLocalForPCD.get();
		String cookieFormatFromPCD=null;
		if(null!=PCD)
		{
			cookieFormatFromPCD= PCD.getfromDate()
					+ "|" + PCD.gettoDate()+"|"+PCD.getnumberOfBooks();
		}
		threadLocalForCookieString.set(cookieFormatFromPCD);
		return cookieFormatFromPCD;

	}
public PCData getCookieValues()
	{
		if(cookieValueChanged)
		{
			return threadLocalForPersistentCookieData.get();
		}
		else
		{
			return null;
			
		}
		
	}

	
}

3)PCD //getters and setters for all fields

public class PCD
{
//getters and setters thru DI
	
	String fromDate="";
	String toDate="";
	String numberOfBooks="";
	public String getnumberOfBooks() {
		return numberOfBooks;
	}
	public void setnumberOfBooks(String numberOfBooks) {
		this.numberOfBooks = numberOfBooks;
	}
	public String getfromDate() {
		return fromDate;
	}
	public void setfromDate(String fromDate) {
		this.fromDate = fromDate;
	}
	public String gettoDate() {
		return toDate;
	}
	public void settoDate(String toDate) {
		this.toDate = toDate;
	}
	
	
	
	
}

The GSP (Groovy Server pages) , i want to get the PCD from threadLoca object and display the cookie values in the respective GSP

<g:form mapping="listPage" action="listPage">
	Destination : <input type="text" id="destination" name="destination"/>
	FromDate<input type="text" id="checkInDate" name="checkInDate" />
	ToDate<input type="text" id="checkOutDate" name="checkOutDate"/>
	NoOfRooms<g:select name="numberofrooms" id="numberofrooms" from="${1..3}" value="text"/>
	<input type="submit" value="Search"/>
</g:form>
<g:if test="${cookie(name:'cookieFormat')}">
println ${cookie(name:'cookieFormat')}
</g:if>

[David Newton]

You don't actually say what the problem is.

I found your code difficult to read. It also looks like the PCH.getCookieString() method is using an instance variable in a singleton--it's being *loaded* with a ThreadLocal, but it itself is not. Admittedly, I use ThreadLocals only rarely, and not recently, but this strikes me as incorrect.

A couple of code cleanups (in addition to suggesting that you choose a single brace-placement style and stick with it rather than arbitrarily doing same-line/new-line):

	public Boolean hasCookieChanged(HttpServletRequest req) {
		String cookieFormatFromPCD = getCookieString();
		if (cookieFormatFromPCD == null) {
		    return false;
		}
		
		String singleCookie = getCookieByName(req, "singleCookie");
		return cookieFormatFromPCD.equals(singleCookie);
	}

	public Cookie getCookieByName(HttpServletRequest req, String name) {
		Cookie[] cookies = req.getCookies();
		if (CollectionUtils.isEmpty(cookies)) {
		    return null;
		}

        for (Cookie c : cookies) {
			if (c.getName().equals(name)) {
			    return c;
			}
		}
		
		return null;
	}

        public PCData getCookieValues() {
            return cookieValueChanged ? threadLocalForPersistentCookieData.get() : null;
	}

If this is Groovy (which I'm assuming it is, but only because of that last getCookieValues() method and its property access shortcut), please *state* what language it's in. Refactor your conditionals--they're essentially unreadable:

if((null!=(fromDate=(String)req.getParameter("fromDate")))&&(null!=(toDate=(String)req.getParameter("toDate")))&&(null!=(numberOfBooks=(String)req.getParameter("numberofbooks"))))

Ew. In general, particularly when it's a mash of characters like this, I wouldn't recommend doing assignments here either.

[Maan Suraj]

Thanks David for replying.
Let me try to be more clear

You don't actually say what the problem is.

Problem is sinmple
GSP code

<%
PCH persch=SBCFilter.persistCH;
PCData persistcd=null;
persch.persistcd=persch.getCookValues();
%>

Assume above works."persch" is a static variable." persistcd" is an instance variable in class PCH.
Assume "persch.persistcd", gets reference to a bean object of type PCData .PCData is simply getters and setters.
Now assuming above all works, i want to populate these fields below without using scripts.Currently i am doing below

 <g:form mapping="listPage" action="listPage">  
     Destination : <input type="text" id="destination" name="destination" value=<%=persch.persistcd.getDestinationName()%>>      
     <input type="submit" value=""/>  
 </g:form>  

Now i dont want to use scriptlet to retrieve my value.I want some other option

The framework used is grails and above is a groovy server page

Thanks in advance

[David Newton]

Wouldn't you just put the same object into the page's model and get it normally? Or with ${} notation? Or fill the value in the controller and use the text input tag?

GSP Intro

[Maan Suraj]

i thought of using <jsp:get property....etc>, though it is a GSP page. is it possible?

[Bear Bibeault]

<g:form>? Not a JSP tag. If you are using a framework, you need to clearly state that.

[Maan Suraj]

I am using Grails Framework.

[David Newton]

Moved to Groovy/Grails forum. Please make sure you choose the best forum for questions; thanks.