public class

BasicTokenIterator

extends Object
implements TokenIterator
java.lang.Object
   ↳ org.apache.http.message.BasicTokenIterator

Class Overview

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.

Summary

Constants
String HTTP_SEPARATORS The HTTP separator characters.
Fields
protected String currentHeader The value of the current header.
protected String currentToken The token to be returned by the next call to currentToken.
protected final HeaderIterator headerIt The iterator from which to obtain the next header.
protected int searchPos The position after currentToken in currentHeader.
Public Constructors
BasicTokenIterator(HeaderIterator headerIterator)
Creates a new instance of BasicTokenIterator.
Public Methods
boolean hasNext()
Indicates whether there is another token in this iteration.
final Object next()
Returns the next token.
String nextToken()
Obtains the next token from this iteration.
final void remove()
Removing tokens is not supported.
Protected Methods
String createToken(String value, int start, int end)
Creates a new token to be returned.
int findNext(int from)
Determines the next token.
int findTokenEnd(int from)
Determines the ending position of the current token.
int findTokenSeparator(int from)
Determines the position of the next token separator.
int findTokenStart(int from)
Determines the starting position of the next token.
boolean isHttpSeparator(char ch)
Checks whether a character is an HTTP separator.
boolean isTokenChar(char ch)
Checks whether a character is a valid token character.
boolean isTokenSeparator(char ch)
Checks whether a character is a token separator.
boolean isWhitespace(char ch)
Checks whether a character is a whitespace character.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.util.Iterator
From interface org.apache.http.TokenIterator

Constants

public static final String HTTP_SEPARATORS

The HTTP separator characters. Defined in RFC 2616, section 2.2.

Constant Value: " ,;=()<>@:\"/[]?{} "

Fields

protected String currentHeader

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

protected String currentToken

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

protected final HeaderIterator headerIt

The iterator from which to obtain the next header.

protected int searchPos

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

Public Constructors

public BasicTokenIterator (HeaderIterator headerIterator)

Creates a new instance of BasicTokenIterator.

Parameters
headerIterator the iterator for the headers to tokenize

Public Methods

public boolean hasNext ()

Indicates whether there is another token in this iteration.

Returns
  • true if there is another token, false otherwise

public final Object next ()

Returns the next token. Same as nextToken(), but with generic return type.

Returns
  • the next token in this iteration
Throws
NoSuchElementException if there are no more tokens
ParseException if an invalid header value is encountered

public String nextToken ()

Obtains the next token from this iteration.

Returns
  • the next token in this iteration
Throws
NoSuchElementException if the iteration is already over
ParseException if an invalid header value is encountered

public final void remove ()

Removing tokens is not supported.

Throws
UnsupportedOperationException always

Protected Methods

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

protected int findNext (int from)

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

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.

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 #.

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

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

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

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

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