Java Reference
In-Depth Information
The
text/*
media type means any text format.
Preference Ordering
The protocol also has both implicit and explicit rules for choosing a media type to respond
with. The implicit rule is that more specific media types take precedence over less specific
ones. Take this example:
GET http://example.com/stuff
Accept: text/*, text/html;level=1, */*, application/xml
The server assumes that the client always wants a concrete media type over a wildcard one,
so the server would interpret the client preference as follows:
1.
text/html;level=1
2.
application/xml
3.
text/*
4.
*/*
The
text/html;level=1
type would come first because it is the most specific. The
applic-
ation/xml
type would come next because it does not have any MIME type properties like
text/html;level=1
does. After this would come the wildcard types, with
text/*
coming
first because it is obviously more concrete than the match-all qualifier
*/*
.
Clients can also be more specific on their preferences by using the
q
MIME type property.
This property is a numeric value between 0.0 and 1.0, with 1.0 being the most preferred. For
example:
GET http://example.com/stuff
Accept: text
/*;q=0.9, */*;q=0.1,
audio/mpeg, application/xml
;q=0.5
If no
q
qualifier is given, then a value of
1.0
must be assumed. So, in our example request,
the preference order is as follows:
1.
audio/mpeg
2.
text/*
3.
application/xml
4.
*/*
The
audio/mpeg
type is chosen first because it has an implicit qualifier of
1.0
. Text types
come next, as
text/*
has a qualifier of
0.9
. Even though
application/xml
is more specif-
ic, it has a lower preference value than
text/*
, so it follows in the third spot. If none of
