Class Headers
Map
<String
,
List
<String
>>.
The keys are case-insensitive Strings representing the header names and
the value associated with each key is
a List
<String
> with one
element for each occurrence of the header name in the request or response.
For example, if a response header instance contains one key "HeaderName" with two values "value1 and value2" then this object is output as two header lines:
All the normalHeaderName: value1 HeaderName: value2
Map
methods are provided, but the
following additional convenience methods are most likely to be used:
getFirst(String)
returns a single valued header or the first value of a multi-valued header.add(String,String)
adds the given header value to the list for the given key.set(String,String)
sets the given header field to the single value given overwriting any existing values in the value list.
An instance of Headers
is either mutable or immutable.
A mutable headers allows to add, remove, or modify header names and
values, e.g. the instance returned by HttpExchange.getResponseHeaders()
.
An immutable headers disallows any modification to header names or
values, e.g. the instance returned by HttpExchange.getRequestHeaders()
.
The mutator methods for an immutable headers instance unconditionally throw
UnsupportedOperationException
.
All methods in this class reject null
values for keys and values.
null
keys will never be present in HTTP request or response headers.
- Since:
- 1.6
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Nested Class Summary
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoid
Adds the givenvalue
to the list of headers for the givenkey
.void
clear()
Removes all of the mappings from this map (optional operation).boolean
containsKey
(Object key) Returnstrue
if this map contains a mapping for the specified key.boolean
containsValue
(Object value) Returnstrue
if this map maps one or more keys to the specified value.entrySet()
Returns aSet
view of the mappings contained in this map.boolean
Compares the specified object with this map for equality.Returns the value to which the specified key is mapped, ornull
if this map contains no mapping for the key.Returns the first value from theList
ofString
values for the givenkey
, ornull
if no mapping for thekey
exists.int
hashCode()
Returns the hash code value for this map.boolean
isEmpty()
Returnstrue
if this map contains no key-value mappings.keySet()
Returns aSet
view of the keys contained in this map.static Headers
Returns an immutableHeaders
with the given name value pairs as its set of headers.static Headers
Returns an immutableHeaders
from the givenheaders
with the same header names and values.Associates the specified value with the specified key in this map (optional operation).void
Copies all of the mappings from the specified map to this map (optional operation).Removes the mapping for a key from this map if it is present (optional operation).void
Sets the givenvalue
as the sole header value for the givenkey
.int
size()
Returns the number of key-value mappings in this map.values()
Returns aCollection
view of the values contained in this map.Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface java.util.Map
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
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Constructor Details
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Headers
public Headers()Creates an empty instance ofHeaders
. -
Headers
Creates a mutableHeaders
from the givenheaders
with the same header names and values.- Parameters:
headers
- a map of header names and values- Throws:
NullPointerException
- ifheaders
or any of its names or values are null, or if any value contains null.- Since:
- 18
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Method Details
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size
public int size()Description copied from interface:Map
Returns the number of key-value mappings in this map. If the map contains more thanInteger.MAX_VALUE
elements, returnsInteger.MAX_VALUE
. -
isEmpty
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containsKey
Description copied from interface:Map
Returnstrue
if this map contains a mapping for the specified key. More formally, returnstrue
if and only if this map contains a mapping for a keyk
such thatObjects.equals(key, k)
. (There can be at most one such mapping.)- Specified by:
containsKey
in interfaceMap<String,
List<String>> - Parameters:
key
- key whose presence in this map is to be tested- Returns:
true
if this map contains a mapping for the specified key
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containsValue
Description copied from interface:Map
Returnstrue
if this map maps one or more keys to the specified value. More formally, returnstrue
if and only if this map contains at least one mapping to a valuev
such thatObjects.equals(value, v)
. This operation will probably require time linear in the map size for most implementations of theMap
interface.- Specified by:
containsValue
in interfaceMap<String,
List<String>> - Parameters:
value
- value whose presence in this map is to be tested- Returns:
true
if this map maps one or more keys to the specified value
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get
Description copied from interface:Map
Returns the value to which the specified key is mapped, ornull
if this map contains no mapping for the key.More formally, if this map contains a mapping from a key
k
to a valuev
such thatObjects.equals(key, k)
, then this method returnsv
; otherwise it returnsnull
. (There can be at most one such mapping.)If this map permits null values, then a return value of
null
does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key tonull
. ThecontainsKey
operation may be used to distinguish these two cases. -
getFirst
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put
Description copied from interface:Map
Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A mapm
is said to contain a mapping for a keyk
if and only ifm.containsKey(k)
would returntrue
.)- Specified by:
put
in interfaceMap<String,
List<String>> - Parameters:
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified key- Returns:
- the previous value associated with
key
, ornull
if there was no mapping forkey
. (Anull
return can also indicate that the map previously associatednull
withkey
, if the implementation supportsnull
values.)
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add
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set
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remove
Description copied from interface:Map
Removes the mapping for a key from this map if it is present (optional operation). More formally, if this map contains a mapping from keyk
to valuev
such thatObjects.equals(key, k)
, that mapping is removed. (The map can contain at most one such mapping.)Returns the value to which this map previously associated the key, or
null
if the map contained no mapping for the key.If this map permits null values, then a return value of
null
does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key tonull
.The map will not contain a mapping for the specified key once the call returns.
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putAll
Description copied from interface:Map
Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of callingput(k, v)
on this map once for each mapping from keyk
to valuev
in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress. If the specified map has a defined encounter order, processing of its mappings generally occurs in that order. -
clear
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keySet
Description copied from interface:Map
Returns aSet
view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's ownremove
operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove
,Set.remove
,removeAll
,retainAll
, andclear
operations. It does not support theadd
oraddAll
operations. -
values
Description copied from interface:Map
Returns aCollection
view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress (except through the iterator's ownremove
operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via theIterator.remove
,Collection.remove
,removeAll
,retainAll
andclear
operations. It does not support theadd
oraddAll
operations. -
entrySet
Description copied from interface:Map
Returns aSet
view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's ownremove
operation, or through thesetValue
operation on a map entry returned by the iterator) the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove
,Set.remove
,removeAll
,retainAll
andclear
operations. It does not support theadd
oraddAll
operations. -
equals
Description copied from interface:Map
Compares the specified object with this map for equality. Returnstrue
if the given object is also a map and the two maps represent the same mappings. More formally, two mapsm1
andm2
represent the same mappings ifm1.entrySet().equals(m2.entrySet())
. This ensures that theequals
method works properly across different implementations of theMap
interface. -
hashCode
public int hashCode()Description copied from interface:Map
Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hash codes of each entry in the map'sentrySet()
view. This ensures thatm1.equals(m2)
implies thatm1.hashCode()==m2.hashCode()
for any two mapsm1
andm2
, as required by the general contract ofObject.hashCode()
. -
of
Returns an immutableHeaders
with the given name value pairs as its set of headers.The supplied
String
instances must alternate as header names and header values. To add several values to the same name, the same name must be supplied with each new value. If the suppliedheaders
is empty, then an emptyHeaders
is returned.- Parameters:
headers
- the list of name value pairs- Returns:
- an immutable headers with the given name value pairs
- Throws:
NullPointerException
- ifheaders
or any of its elements are null.IllegalArgumentException
- if the number of supplied strings is odd.- Since:
- 18
-
of
Returns an immutableHeaders
from the givenheaders
with the same header names and values.- Parameters:
headers
- a map of header names and values- Returns:
- an immutable headers
- Throws:
NullPointerException
- ifheaders
or any of its names or values are null, or if any value contains null.- Since:
- 18
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