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Class HTTPClient.Util

java.lang.Object
    |
    +----HTTPClient.Util

public class Util
extends Object
This class holds various utility methods.

Version:
0.3 30/01/1998
Author:
Ronald Tschalär

Method Index

 o assembleHeader(Vector)
Assembles a Vector of HttpHeaderElements into a full header string.
 o defaultPort(String)
Return the default port used by a given protocol.
 o dequoteString(String)
Replace quoted characters by their unquoted version.
 o getElement(Vector, String)
Get the HttpHeaderElement with the name name.
 o getFragment(String)
Extract the fragment part from an http resource.
 o getParameter(String, String)
retrieves the value associated with the parameter param in a given header string.
 o getParams(String)
Extract the params part from an http resource.
 o getPath(String)
Extract the path from an http resource.
 o getQuery(String)
Extract the query string from an http resource.
 o hasToken(String, String)
Determines if the given header contains a certain token.
 o httpDate(Date)
This returns a string containing the date and time in date formatted according to a subset of RFC-1123.
 o parseHeader(String)
This parses the value part of a header.
 o parseHeader(String, boolean)
This parses the value part of a header.
 o quoteString(String, String)
Replace given characters by their quoted version.
 o sameHttpURL(URL, URL)
Compares two http urls for equality.

Methods

 o dequoteString
public static final String dequoteString(String str)
Replace quoted characters by their unquoted version. Quoted characters are characters preceded by a slash. E.g. "\c" would be replaced by "c". This is used in parsing http headers where quoted-characters are allowed in quoted-strings and often used to quote the quote character <">.

Parameters:
str - the string do dequote
Returns:
the string do with all quoted characters replaced by their true value.
 o quoteString
public static final String quoteString(String str,
                                       String qlist)
Replace given characters by their quoted version. Quoted characters are characters preceded by a slash. E.g. "c" would be replaced by "\c". This is used in generating http headers where certain characters need to be quoted, such as the quote character <">.

Parameters:
str - the string do quote
qlist - the list of characters to quote
Returns:
the string do with all characters replaced by their quoted version.
 o parseHeader
public static final Vector parseHeader(String header) throws ParseException
This parses the value part of a header. All quoted strings are dequoted.

Parameters:
header - the value part of the header.
Returns:
a Vector containing all the elements; each entry is an instance of HttpHeaderElement.
Throws: ParseException
if the syntax rules are violated.
See Also:
parseHeader
 o parseHeader
public static final Vector parseHeader(String header,
                                       boolean dequote) throws ParseException
This parses the value part of a header. The result is a Vector of HttpHeaderElement's. The syntax the header must conform to is:
    header  = [ element ] *( "," [ element ] )
    element = name [ "=" [ value ] ] *( ";" [ param ] )
    param   = name [ "=" [ value ] ]

    name    = token
    value   = ( token | quoted-string )

    token         = 1*<any char except "=", ",", ";", <"> and
    white space>
    quoted-string = <"> *( text | quoted-char ) <">
    text          = any char except <">
    quoted-char   = "\" char
Any amount of white space is allowed between any part of the header, element or param and is ignored. A missing value in any element or param will be stored as the empty string; if the "=" is also missing null will be stored instead.

Parameters:
header - the value part of the header.
dequote - if true all quoted strings are dequoted.
Returns:
a Vector containing all the elements; each entry is an instance of HttpHeaderElement.
Throws: ParseException
if the above syntax rules are violated.
See Also:
HttpHeaderElement
 o hasToken
public static final boolean hasToken(String header,
                                     String token) throws ParseException
Determines if the given header contains a certain token. The header must conform to the rules outlined in parseHeader().

Parameters:
header - the header value.
token - the token to find; the match is case-insensitive.
Returns:
true if the token is present, false otherwise.
Throws: ParseException
if this is thrown parseHeader().
See Also:
parseHeader
 o getElement
public static final HttpHeaderElement getElement(Vector header,
                                                 String name)
Get the HttpHeaderElement with the name name.

Parameters:
header - a vector of HttpHeaderElement's, such as is returned from parseHeader()
name - the name of element to retrieve; matching is case-insensitive
Returns:
the request element, or null if none found.
See Also:
parseHeader
 o getParameter
public static final String getParameter(String param,
                                        String hdr) throws ParseException
retrieves the value associated with the parameter param in a given header string. It parses the header using parseHeader() and then searches the first element for the given parameter. This is used especially in headers like 'Content-type' and 'Content-Disposition'.

quoted characters ("\x") in a quoted string are dequoted.

Parameters:
param - the parameter name
hdr - the header value
Returns:
the value for this parameter, or null if not found.
Throws: ParseException
if the above syntax rules are violated.
See Also:
parseHeader
 o assembleHeader
public static final String assembleHeader(Vector pheader)
Assembles a Vector of HttpHeaderElements into a full header string. The individual header elements are seperated by a ", ".

Parameters:
the - parsed header
Returns:
a string containing the assembled header
 o sameHttpURL
public static final boolean sameHttpURL(URL url1,
                                        URL url2)
Compares two http urls for equality. This exists because the method java.net.URL.sameFile() is broken (an explicit port 80 doesn't compare equal to an implicit port, and it doesn't take escapes into account).

Two http urls are considered equal if they have the same protocol (case-insensitive match), the same host (case-insensitive), the same port and the same file (after decoding escaped characters).

Parameters:
url1 - the first url
url1 - the second url
Returns:
true if url1 and url2 compare equal
 o defaultPort
public static final int defaultPort(String protocol)
Return the default port used by a given protocol.

Parameters:
protocol - the protocol
Returns:
the port number, or 0 if unknown
 o httpDate
public static final String httpDate(Date date)
This returns a string containing the date and time in date formatted according to a subset of RFC-1123. The format is defined in the HTTP/1.0 spec (RFC-1945), section 3.3, and the HTTP/1.1 spec (RFC-2068), section 3.3.1. Note that Date.toGMTString() is close, but is missing the weekday and supresses the leading zero if the day is less than the 10th. Instead we use the SimpleDateFormat class.

Some versions of JDK 1.1.x are bugged in that their GMT uses daylight savings time... Therefore we use our own timezone definitions.

Parameters:
date - the date and time to be converted
Returns:
a string containg the date and time as used in http
 o getPath
public static final String getPath(String resource)
Extract the path from an http resource.

The "resource" part of an HTTP URI can contain a number of parts, some of which are not always of interest. These methods here will extract the various parts, assuming the following syntanx (taken from RFC-2068):

    resource = [ "/" ] [ path ] [ ";" params ] [ "?" query ] [ "#" fragment ]

Parameters:
the - resource to split
Returns:
the path, including any leading "/"
See Also:
getParams, getQuery, getFragment
 o getParams
public static final String getParams(String resource)
Extract the params part from an http resource.

Parameters:
the - resource to split
Returns:
the params, or null if there are none
See Also:
getPath
 o getQuery
public static final String getQuery(String resource)
Extract the query string from an http resource.

Parameters:
the - resource to split
Returns:
the query, or null if there was none
See Also:
getPath
 o getFragment
public static final String getFragment(String resource)
Extract the fragment part from an http resource.

Parameters:
the - resource to split
Returns:
the fragment, or null if there was none
See Also:
getPath

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