org.melati.util
Class AcceptCharset

java.lang.Object
  org.melati.util.HttpHeader
      org.melati.util.AcceptCharset

public class AcceptCharset
extends HttpHeader

Representation of the Accept-Charset header fields.

Provides features for choosing a charset according to client or server preferences.

Author:

jimw At paneris.org

Nested Class Summary

static class	AcceptCharset.CharsetAndQValue A charset and associated qvalue.
class	AcceptCharset.CharsetAndQValueIterator Enumeration of AcceptCharset.CharsetAndQValue.
protected static class	AcceptCharset.Comparator Comparator for comparing AcceptCharset.CharsetAndQValue objects.

Nested classes/interfaces inherited from class org.melati.util.HttpHeader

HttpHeader.FieldIterator, HttpHeader.HttpHeaderException, HttpHeader.TokenAndQValue, HttpHeader.TokenAndQValueIterator, HttpHeader.Tokenizer, HttpHeader.WordIterator

Field Summary

protected java.util.HashMap

supportedAcceptedOrPreferred Charsets supported by the jvm and accepted by the client or preferred by the server.

Fields inherited from class org.melati.util.HttpHeader

tokenizer

Constructor Summary

AcceptCharset(java.lang.String values, java.util.List serverPreference)
Create an instance from the Accept-Charset header field values and a set of server preferred charset names.

Method Summary

AcceptCharset.CharsetAndQValueIterator	charsetAndQValueIterator() Factory method to create and return the next HttpHeader.TokenAndQValue.
java.lang.String	choice(AcceptCharset.Comparator comparator) If there is none, return null, and the caller can either use an unacceptable character set or generate a 406 error.
java.lang.String	clientChoice()
HttpHeader.TokenAndQValue	nextTokenAndQValue() Factory method to create and return the next HttpHeader.TokenAndQValue.
java.lang.String	serverChoice()

Methods inherited from class org.melati.util.HttpHeader

tokenAndQValueIterator, wordIterator

Methods inherited from class java.lang.Object

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

Field Detail

supportedAcceptedOrPreferred

protected java.util.HashMap supportedAcceptedOrPreferred

Charsets supported by the jvm and accepted by the client or preferred by the server.

Constructor Detail

AcceptCharset

public AcceptCharset(java.lang.String values,
                     java.util.List serverPreference)
              throws HttpHeader.HttpHeaderException

Create an instance from the Accept-Charset header field values and a set of server preferred charset names.

The field values might have appeared in a single Accept-Charset header or in several that were concatenated with comma separator in order. This concatenation is often done for the caller, by a servlet container or something, but it must be done.

null is taken to mean there were no Accept-Charset header fields.

If a client supported charset is unsupported by the JVM it is ignored. If the caller wants to ensure that there are none then it must check for itself.

If the same charset is specified more than once (perhaps under different names or aliases) then the first occurrence is significant.

The server preferences provides a list of charsets used if there is a wildcard specification. This class does not currently try other available charsets so to avoid 406 errors to reasonable clients, enough reasonable charsets must be listed in serverPreferences.

Throws:

HttpHeader.HttpHeaderException

Method Detail

nextTokenAndQValue

public HttpHeader.TokenAndQValue nextTokenAndQValue()
                                             throws HttpHeader.HttpHeaderException

Factory method to create and return the next HttpHeader.TokenAndQValue.

Overrides:

nextTokenAndQValue in class HttpHeader

Returns:

a new TokenAndQValue

Throws:

HttpHeader.HttpHeaderException

See Also:

HttpHeader.nextTokenAndQValue()

charsetAndQValueIterator

public AcceptCharset.CharsetAndQValueIterator charsetAndQValueIterator()

Factory method to create and return the next HttpHeader.TokenAndQValue.

Returns:

a new Iterator

clientChoice

public java.lang.String clientChoice()

Returns:

the first supported charset that is also acceptable to the client in order of client preference.

serverChoice

public java.lang.String serverChoice()

Returns:

the first supported charset also acceptable to the client in order of server preference.

choice

public java.lang.String choice(AcceptCharset.Comparator comparator)

If there is none, return null, and the caller can either use an unacceptable character set or generate a 406 error. see #firstOther

Returns:

the first supported charset also acceptable to the client in order defined by the given AcceptCharset.Comparator