Package org.apache.http.message

Class BasicTokenIterator

java.lang.Object
org.apache.http.message.BasicTokenIterator
All Implemented Interfaces:
Iterator, TokenIterator
public class BasicTokenIterator
extends Object
implements TokenIterator
Basic implementation of a TokenIterator. This implementation parses #token sequences as defined by RFC 2616, section 2. It extends that definition somewhat beyond US-ASCII.
Version:
$Revision: 602520 $

  • Field Details

    • HTTP_SEPARATORS

      public static final String HTTP_SEPARATORS
      The HTTP separator characters. Defined in RFC 2616, section 2.2.
      See Also:
      Constant Field Values

    • headerIt

      protected final HeaderIterator headerIt
      The iterator from which to obtain the next header.

    • currentHeader

      protected String currentHeader
      The value of the current header. This is the header value that includes currentToken. Undefined if the iteration is over.

    • currentToken

      protected String currentToken
      The token to be returned by the next call to currentToken. null if the iteration is over.

    • searchPos

      protected int searchPos
      The position after currentToken in currentHeader. Undefined if the iteration is over.

  • Constructor Details

    • BasicTokenIterator

      public BasicTokenIterator​(HeaderIterator headerIterator)
      Creates a new instance of BasicTokenIterator.
      Parameters:
      headerIterator - the iterator for the headers to tokenize

  • Method Details

    • hasNext

      public boolean hasNext()
      Description copied from interface: TokenIterator
      Indicates whether there is another token in this iteration.
      Specified by:
      hasNext in interface Iterator
      Specified by:
      hasNext in interface TokenIterator
      Returns:
      true if there is another token, false otherwise
      See Also:
      Iterator.next()

    • nextToken

      public String nextToken() throws NoSuchElementException, ParseException
      Obtains the next token from this iteration.
      Specified by:
      nextToken in interface TokenIterator
      Returns:
      the next token in this iteration
      Throws:
      NoSuchElementException - if the iteration is already over
      ParseException - if an invalid header value is encountered

    • next

      public final Object next() throws NoSuchElementException, ParseException
      Returns the next token. Same as nextToken(), but with generic return type.
      Specified by:
      next in interface Iterator
      Returns:
      the next token in this iteration
      Throws:
      NoSuchElementException - if there are no more tokens
      ParseException - if an invalid header value is encountered
      See Also:
      Iterator.hasNext()

    • remove

      public final void remove() throws UnsupportedOperationException
      Removing tokens is not supported.
      Specified by:
      remove in interface Iterator
      Throws:
      UnsupportedOperationException - always

    • findNext

      protected int findNext​(int from) throws ParseException
      Determines the next token. If found, the token is stored in currentToken. The return value indicates the position after the token in currentHeader. If necessary, the next header will be obtained from headerIt. If not found, currentToken is set to null.
      Parameters:
      from - the position in the current header at which to start the search, -1 to search in the first header
      Returns:
      the position after the found token in the current header, or negative if there was no next token
      Throws:
      ParseException - if an invalid header value is encountered

    • createToken

      protected String createToken​(String value, int start, int end)
      Creates a new token to be returned. Called from findNext after the token is identified. The default implementation simply calls String.substring.
      If header values are significantly longer than tokens, and some tokens are permanently referenced by the application, there can be problems with garbage collection. A substring will hold a reference to the full characters of the original string and therefore occupies more memory than might be expected. To avoid this, override this method and create a new string instead of a substring.
      Parameters:
      value - the full header value from which to create a token
      start - the index of the first token character
      end - the index after the last token character
      Returns:
      a string representing the token identified by the arguments

    • findTokenStart

      protected int findTokenStart​(int from)
      Determines the starting position of the next token. This method will iterate over headers if necessary.
      Parameters:
      from - the position in the current header at which to start the search
      Returns:
      the position of the token start in the current header, negative if no token start could be found

    • findTokenSeparator

      protected int findTokenSeparator​(int from)
      Determines the position of the next token separator. Because of multi-header joining rules, the end of a header value is a token separator. This method does therefore not need to iterate over headers.
      Parameters:
      from - the position in the current header at which to start the search
      Returns:
      the position of a token separator in the current header, or at the end
      Throws:
      ParseException - if a new token is found before a token separator. RFC 2616, section 2.1 explicitly requires a comma between tokens for #.

    • findTokenEnd

      protected int findTokenEnd​(int from)
      Determines the ending position of the current token. This method will not leave the current header value, since the end of the header value is a token boundary.
      Parameters:
      from - the position of the first character of the token
      Returns:
      the position after the last character of the token. The behavior is undefined if from does not point to a token character in the current header value.

    • isTokenSeparator

      protected boolean isTokenSeparator​(char ch)
      Checks whether a character is a token separator. RFC 2616, section 2.1 defines comma as the separator for #token sequences. The end of a header value will also separate tokens, but that is not a character check.
      Parameters:
      ch - the character to check
      Returns:
      true if the character is a token separator, false otherwise

    • isWhitespace

      protected boolean isWhitespace​(char ch)
      Checks whether a character is a whitespace character. RFC 2616, section 2.2 defines space and horizontal tab as whitespace. The optional preceeding line break is irrelevant, since header continuation is handled transparently when parsing messages.
      Parameters:
      ch - the character to check
      Returns:
      true if the character is whitespace, false otherwise

    • isTokenChar

      protected boolean isTokenChar​(char ch)
      Checks whether a character is a valid token character. Whitespace, control characters, and HTTP separators are not valid token characters. The HTTP specification (RFC 2616, section 2.2) defines tokens only for the US-ASCII character set, this method extends the definition to other character sets.
      Parameters:
      ch - the character to check
      Returns:
      true if the character is a valid token start, false otherwise

    • isHttpSeparator

      protected boolean isHttpSeparator​(char ch)
      Checks whether a character is an HTTP separator. The implementation in this class checks only for the HTTP separators defined in RFC 2616, section 2.2. If you need to detect other separators beyond the US-ASCII character set, override this method.
      Parameters:
      ch - the character to check
      Returns:
      true if the character is an HTTP separator