submitting special characters in html form

You can decode it if necessary, but how exactly are you receiving and reading it? Normally it shouldn't need decoding

try ti use
Class URLDecoder

http://download.oracle.com/javase/6/docs/api/java/net/URLDecoder.html

This is waht URLDecoder will do:
The following rules are applied in the conversion:

    The alphanumeric characters "a" through "z", "A" through "Z" and "0" through "9" remain the same.
    The special characters ".", "-", "*", and "_" remain the same.
    The plus sign "+" is converted into a space character " " .
    A sequence of the form "%xy" will be treated as representing a byte where xy is the two-digit hexadecimal representation of the 8 bits. Then, all substrings that contain one or more of these byte sequences consecutively will be replaced by the character(s) whose encoding would result in those consecutive bytes. The encoding scheme used to decode these characters may be specified, or if unspecified, the default encoding of the platform will be used

This is example:

String shtml = "http://search.barnesandnoble.com/booksearch/first%20book.pdf";

        System.out.println(URLDecoder.decode(shtml));
        

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Output:

http://search.barnesandnoble.com/booksearch/first book.pdf

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this is better as it will not write deprecated warning:

            try{
String shtml = "http://search.barnesandnoble.com/booksearch/first%20book.pdf";

        System.out.println(URLDecoder.decode(shtml, "UTF-8"));
            }catch(Exception ex){
                ex.printStackTrace();
            }

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http://search.barnesandnoble.com/booksearch/first book.pdf

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The proper way to do this would normally be the following

a. *en*code the parameter (if sending manually - otherwise the browser will do it)
b.  treat it as a normal string at the server end (which will decode it usually)

I  have not tried the solution. but i am accepting this