com.bigdata.util.httpd

Class HTTPHeaderUtility

java.lang.Object

com.bigdata.util.httpd.HTTPHeaderUtility

public class HTTPHeaderUtility
extends Object

This class provides set of utilities for encoding and decoding HTTP headers and doubles as the base class for all classes that implement support for a specific HTTP header, such as LinkHeader, AcceptHeader, etc.

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	httpQuotedStringPattern The text for a Pattern matching an HTTP quoted-string.
protected static String	httpTokenPattern Matches an HTTP token, which consists of one or more of any CHAR except CTL or separator.
protected static org.apache.log4j.Logger	log The Logger for HTTP header operations, including parsing and serialization.
protected static Pattern	m_p1 Pattern used to match the type/subtype of a MIME expression.
protected static Pattern	m_p2 Pattern used to match the optional parameters of a MIME expression.
protected static String	qs The text for a Pattern matching an HTTP quoted-string.
protected static String	tok Matches an HTTP token, which consists of one or more of any CHAR except CTL or separator.

Constructor Summary

Constructors

Constructor and Description
HTTPHeaderUtility()

Method Summary

Methods

Modifier and Type	Method and Description
static String	combineHeaders(Enumeration values, String defaultValue) HTTP permits headers whose grammar is a comma delimited list to be specified multiple times in an HTTP request.
protected static void	init() Initialization for shared Pattern object that matches valid MIME type expressions.
static boolean	isHttpCtlChar(char ch) Returns true iff the character is an HTTP CTL character.
static boolean	isHttpSeparatorChar(char ch) Returns true iff the character is an HTTP separator character.
static boolean	isHttpToken(String token) Returns true iff the String obeys the syntax rules for an HTTP token.
static String	quoteString(String value, boolean force) Returns the MIME type parameter value as either an HTTP token or HTTP quoted-string depending on whether or not it contains any characters that need to be escaped.
static String[]	splitCommaList(String value) Splits out the elements for an HTTP header value whose grammar is a comma delimited list.
static String	unquoteString(String value) If the value is an HTTP quoted-string then we strip of the quote characters now and translate any escaped characters into themselves, e.g., '\"' => '"'.

Methods inherited from class java.lang.Object

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

Field Detail

log

protected static final org.apache.log4j.Logger log

The Logger for HTTP header operations, including parsing and serialization. The Logger is named for this class. It should be used by all derived classes.

httpTokenPattern

protected static final String httpTokenPattern

Matches an HTTP token, which consists of one or more of any CHAR except CTL or separator.

See Also:

Constant Field Values

httpQuotedStringPattern

protected static final String httpQuotedStringPattern

The text for a Pattern matching an HTTP quoted-string.

From HTTP/1.1:

A string of text is parsed as a single word if it is quoted using double-quote marks.

The backslash character '\' MAY be used as a single-character quoting mechanism only within quoted-string and comment constructs.

quoted-string = ( <"> *(qdtext | quoted-pair ) <"> )
qdtext = >
quoted-pair = "\" CHAR
TEXT = 

Note: This pattern text uses a non-capturing group to encapsulate the choice between a legal character (TEXT) and an escaped character (quoted-pair) within the context of the quoted-string. Any quoted-pair sequences must be reversed by the consumer of the matched group.

See Also:

Constant Field Values

tok

protected static final String tok

Matches an HTTP token, which consists of one or more of any CHAR except CTL or separator.

See Also:

Constant Field Values

qs

protected static final String qs

The text for a Pattern matching an HTTP quoted-string.

From HTTP/1.1:

A string of text is parsed as a single word if it is quoted using double-quote marks.

The backslash character '\' MAY be used as a single-character quoting mechanism only within quoted-string and comment constructs.

quoted-string = ( <"> *(qdtext | quoted-pair ) <"> )
qdtext = >
quoted-pair = "\" CHAR
TEXT = 

Note: This pattern text uses a non-capturing group to encapsulate the choice between a legal character (TEXT) and an escaped character (quoted-pair) within the context of the quoted-string. Any quoted-pair sequences must be reversed by the consumer of the matched group.

See Also:

Constant Field Values

m_p1

protected static Pattern m_p1

Pattern used to match the type/subtype of a MIME expression. The matched groups are numbered by the opening parentheses in the pattern. The different matching groups are:

• group(0) : the matched input.
• group(1) : type
• group(2) : subtype
• group(3) : the rest of the input, to which you then apply m_p2.

m_p2

protected static Pattern m_p2

Pattern used to match the optional parameters of a MIME expression. The matched groups are numbered by the opening parentheses in the pattern. The source for the pattern is the parameters as identified by m_p1. The different matching groups are:

• group( 0 ) : parameter ( attribute=value ).
• group( 1 ) : attribute (parameter name).
• group( 2 ) : value for that parameter.

Note: You should match this pattern repeatedly until the input is exhausted.

Constructor Detail

HTTPHeaderUtility

public HTTPHeaderUtility()

Method Detail

isHttpCtlChar

public static boolean isHttpCtlChar(char ch)

Returns true iff the character is an HTTP CTL character.

isHttpSeparatorChar

public static boolean isHttpSeparatorChar(char ch)

Returns true iff the character is an HTTP separator character.

isHttpToken

public static boolean isHttpToken(String token)

Returns true iff the String obeys the syntax rules for an HTTP token.

init

protected static void init()

Initialization for shared Pattern object that matches valid MIME type expressions.

quoteString

public static String quoteString(String value,
                 boolean force)

Returns the MIME type parameter value as either an HTTP token or HTTP quoted-string depending on whether or not it contains any characters that need to be escaped.

Parameters:

force - When true the returned value is always a quoted-string.

unquoteString

public static String unquoteString(String value)
                            throws IllegalArgumentException

If the value is an HTTP quoted-string then we strip of the quote characters now and translate any escaped characters into themselves, e.g., '\"' => '"'. Otherwise returns value.

Parameters:

IllegalArgumentException - If the value is a malformed quoted string. For example, no closing quote character or no character after an escape character.

Throws:

IllegalArgumentException

combineHeaders

public static String combineHeaders(Enumeration values,
                    String defaultValue)

HTTP permits headers whose grammar is a comma delimited list to be specified multiple times in an HTTP request. This method propertly combines the specified values need into a String containing a comma-delimited list that preserves the order in which the header values were specified.

Parameters:

values - E.g., as returned by javax.servlet.http#getHeaders( String name ).

defaultValue - IFF enum is an empty enumeration, then this value is returned to the caller.

splitCommaList

public static String[] splitCommaList(String value)

Splits out the elements for an HTTP header value whose grammar is a comma delimited list.