# Class RFC2231Utility

java.lang.Object
org.apache.tomcat.util.http.fileupload.util.mime.RFC2231Utility

public final class RFC2231Utility extends Object
Utility class to decode/encode character set on HTTP Header fields based on RFC 2231. This implementation adheres to RFC 5987 in particular, which was defined for HTTP headers.

RFC 5987 builds on RFC 2231, but has lesser scope like mandatory charset definition and no parameter continuation

See Also:
  - RFC 2231
  - RFC 5987

- ## Method Summary

  Modifier and Type
  Method
  Description
  `static String`
  `decodeText(String encodedText)`
  Decode a string of text obtained from a HTTP header as per RFC 2231
  `static boolean`
  `hasEncodedValue(String paramName)`
  Checks if Asterisk (*) at the end of parameter name to indicate, if it has charset and language information to decode the value.
  `static String`
  `stripDelimiter(String paramName)`
  If `paramName` has Asterisk (*) at the end, it will be stripped off, else the passed value will be returned.

  ### Methods inherited from class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Method Details

  - ### hasEncodedValue

    public static boolean hasEncodedValue(String paramName)
    Checks if Asterisk (*) at the end of parameter name to indicate, if it has charset and language information to decode the value.
    Parameters:
      `paramName` - The parameter, which is being checked.
    Returns:
      `true`, if encoded as per RFC 2231, `false` otherwise

  - ### stripDelimiter

    public static String stripDelimiter(String paramName)
    If `paramName` has Asterisk (*) at the end, it will be stripped off, else the passed value will be returned.
    Parameters:
      `paramName` - The parameter, which is being inspected.
    Returns:
      stripped `paramName` of Asterisk (*), if RFC2231 encoded

  - ### decodeText

    public static String decodeText(String encodedText) throws UnsupportedEncodingException
    Decode a string of text obtained from a HTTP header as per RFC 2231

    Eg 1. `us-ascii'en-us'This%20is%20%2A%2A%2Afun%2A%2A%2A` will be decoded to `This is ***fun***`

    Eg 2. `iso-8859-1'en'%A3%20rate` will be decoded to `£ rate`

    Eg 3. `UTF-8''%c2%a3%20and%20%e2%82%ac%20rates` will be decoded to `£ and € rates`

    Parameters:
      `encodedText` - - Text to be decoded has a format of `<charset>'<language>'<encoded_value>` and ASCII only
    Returns:
      Decoded text based on charset encoding
    Throws:
      `UnsupportedEncodingException` - The requested character set wasn't found.