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
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoidAdds the givenvalueto the list of headers for the givenkey.voidclear()Removes all of the mappings from this map (optional operation).booleancontainsKey(Object key) Returnstrueif this map contains a mapping for the specified key.booleancontainsValue(Object value) Returnstrueif this map maps one or more keys to the specified value.entrySet()Returns aSetview of the mappings contained in this map.booleanCompares the specified object with this map for equality.Returns the value to which the specified key is mapped, ornullif this map contains no mapping for the key.Returns the first value from theListofStringvalues for the givenkey, ornullif no mapping for thekeyexists.inthashCode()Returns the hash code value for this map.booleanisEmpty()Returnstrueif this map contains no key-value mappings.keySet()Returns aSetview of the keys contained in this map.static HeadersReturns an immutableHeaderswith the given name value pairs as its set of headers.static HeadersReturns an immutableHeadersfrom the givenheaderswith the same header names and values.Associates the specified value with the specified key in this map (optional operation).voidCopies 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).voidSets the givenvalueas the sole header value for the givenkey.intsize()Returns the number of key-value mappings in this map.values()Returns aCollectionview of the values contained in this map.Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods 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 mutableHeadersfrom the givenheaderswith the same header names and values.- Parameters:
headers- a map of header names and values- Throws:
NullPointerException- ifheadersor 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:MapReturns the number of key-value mappings in this map. If the map contains more thanInteger.MAX_VALUEelements, returnsInteger.MAX_VALUE. -
isEmpty
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containsKey
Description copied from interface:MapReturnstrueif this map contains a mapping for the specified key. More formally, returnstrueif and only if this map contains a mapping for a keyksuch thatObjects.equals(key, k). (There can be at most one such mapping.)- Specified by:
containsKeyin interfaceMap<String, List<String>>- Parameters:
key- key whose presence in this map is to be tested- Returns:
trueif this map contains a mapping for the specified key
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containsValue
Description copied from interface:MapReturnstrueif this map maps one or more keys to the specified value. More formally, returnstrueif and only if this map contains at least one mapping to a valuevsuch thatObjects.equals(value, v). This operation will probably require time linear in the map size for most implementations of theMapinterface.- Specified by:
containsValuein interfaceMap<String, List<String>>- Parameters:
value- value whose presence in this map is to be tested- Returns:
trueif this map maps one or more keys to the specified value
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get
Description copied from interface:MapReturns the value to which the specified key is mapped, ornullif this map contains no mapping for the key.More formally, if this map contains a mapping from a key
kto a valuevsuch 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
nulldoes not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key tonull. ThecontainsKeyoperation may be used to distinguish these two cases. -
getFirst
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put
Description copied from interface:MapAssociates 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 mapmis said to contain a mapping for a keykif and only ifm.containsKey(k)would returntrue.)- Specified by:
putin 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, ornullif there was no mapping forkey. (Anullreturn can also indicate that the map previously associatednullwithkey, if the implementation supportsnullvalues.)
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add
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set
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remove
Description copied from interface:MapRemoves the mapping for a key from this map if it is present (optional operation). More formally, if this map contains a mapping from keykto valuevsuch 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
nullif the map contained no mapping for the key.If this map permits null values, then a return value of
nulldoes 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:MapCopies 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 keykto valuevin 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:MapReturns aSetview 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 ownremoveoperation), 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, andclearoperations. It does not support theaddoraddAlloperations. -
values
Description copied from interface:MapReturns aCollectionview 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 ownremoveoperation), 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,retainAllandclearoperations. It does not support theaddoraddAlloperations. -
entrySet
Description copied from interface:MapReturns aSetview 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 ownremoveoperation, or through thesetValueoperation 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,retainAllandclearoperations. It does not support theaddoraddAlloperations. -
equals
Description copied from interface:MapCompares the specified object with this map for equality. Returnstrueif the given object is also a map and the two maps represent the same mappings. More formally, two mapsm1andm2represent the same mappings ifm1.entrySet().equals(m2.entrySet()). This ensures that theequalsmethod works properly across different implementations of theMapinterface. -
hashCode
public int hashCode()Description copied from interface:MapReturns 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 mapsm1andm2, as required by the general contract ofObject.hashCode(). -
of
Returns an immutableHeaderswith the given name value pairs as its set of headers.The supplied
Stringinstances 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 suppliedheadersis empty, then an emptyHeadersis returned.- Parameters:
headers- the list of name value pairs- Returns:
- an immutable headers with the given name value pairs
- Throws:
NullPointerException- ifheadersor any of its elements are null.IllegalArgumentException- if the number of supplied strings is odd.- Since:
- 18
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of
Returns an immutableHeadersfrom the givenheaderswith the same header names and values.- Parameters:
headers- a map of header names and values- Returns:
- an immutable headers
- Throws:
NullPointerException- ifheadersor any of its names or values are null, or if any value contains null.- Since:
- 18
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