将超链接中的动态字符串作为jsp中的参数传递

Question

I am trying to pass a dynamic string builder variable in jsp I am generating a string through code. String Builder variable has some value but i am not able to pass it in at run time.It doesn't get the value. CODE FOR VARIABLE

<% 
    StringBuilder sb = new StringBuilder("");
    if (request.getAttribute("Brand") != null) {
        String Brand[] = (String[]) request.getAttribute("Brand");
        for (String brand : Brand) {
            sb.append("Brand=");
            sb.append(brand);
            sb.append("&");
        }
    }
    if (request.getAttribute("Flavour") != null) {
        String Flavour[] = (String[]) request.getAttribute("Flavour");
        for (String flavour : Flavour) {
            sb.append(flavour);
            sb.append("&");
        }
        sb.trimToSize();
        pageContext.setAttribute("sb", sb);
    }
    out.print("this is string" + sb);
%>

CODE FOR HYPERLINK

<a href="Filter_Products?${sb}page=${currentPage + 1}" style="color: white;text-decoration: none;">Next</a></td>

Answer 1

You do need to add sb to the pageContext, request, session or context scope to be able to access it through an EL expression - it will not pick up variables declared only in scriptlets. Modify as follows so that that sb is always put into the pageContext:

if (request.getAttribute("Flavour") != null) {
        String[] flavours = (String[]) request.getAttribute("Flavour");
        for (String flavour : flavours) {
            sb.append(flavour);
            sb.append("&");
        }
        sb.trimToSize();

    }
    pageContext.setAttribute("sb", sb);

I have also suggested a change to improve the clarity of your code when assigning the array of 'flavour' String values.

Answer 2

You are setting the value to pageContext and trying to accessed via ${}. This by default refer to request scope. Try ${pageScope.sb}

Apart from that Your code looks fine, but i'm confused with the &&. Usually the URL parameter are separated by just one & symbol. Why do you need 2?