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.booleanIndicates whether some other object is "equal to" this one.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 a hash code value for the object.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
public boolean isEmpty()Description copied from interface:MapReturnstrueif this map contains no key-value mappings. -
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
Returns the first value from theListofStringvalues for the givenkey, ornullif no mapping for thekeyexists.- Parameters:
key- the key to search for- Returns:
- the first
Stringvalue associated with the key, ornullif no mapping for the key exists
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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
Adds the givenvalueto the list of headers for the givenkey. If the mapping does not already exist, then it is created.- Parameters:
key- the header namevalue- the value to add to the header
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set
Sets the givenvalueas the sole header value for the givenkey. If the mapping does not already exist, then it is created.- Parameters:
key- the header namevalue- the header value to 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
public void clear()Description copied from interface:MapRemoves all of the mappings from this map (optional operation). The map will be empty after this call returns. -
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 class:ObjectIndicates whether some other object is "equal to" this one.The
equalsmethod implements an equivalence relation on non-null object references:- It is reflexive: for any non-null reference value
x,x.equals(x)should returntrue. - It is symmetric: for any non-null reference values
xandy,x.equals(y)should returntrueif and only ify.equals(x)returnstrue. - It is transitive: for any non-null reference values
x,y, andz, ifx.equals(y)returnstrueandy.equals(z)returnstrue, thenx.equals(z)should returntrue. - It is consistent: for any non-null reference values
xandy, multiple invocations ofx.equals(y)consistently returntrueor consistently returnfalse, provided no information used inequalscomparisons on the objects is modified. - For any non-null reference value
x,x.equals(null)should returnfalse.
An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.
- It is reflexive: for any non-null reference value
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hashCode
public int hashCode()Description copied from class:ObjectReturns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided byHashMap.The general contract of
hashCodeis:- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
hashCodemethod must consistently return the same integer, provided no information used inequalscomparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. - If two objects are equal according to the
equalsmethod, then calling thehashCodemethod on each of the two objects must produce the same integer result. - It is not required that if two objects are unequal
according to the
equalsmethod, then calling thehashCodemethod on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.
- Whenever it is invoked on the same object more than once during
an execution of a Java application, the
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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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