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Top Description Fields Constructors Methods
com.sun.net.httpserver

public Class Headers

extends Object
implements Map<String, List<String>>
Class Inheritance
All Implemented Interfaces
java.util.Map
Known Direct Subclasses
sun.net.httpserver.UnmodifiableHeaders
Imports
java.util.Arrays, .Collection, .HashMap, .LinkedList, .List, .Map, .Objects, .Set, java.util.function.BiFunction, java.util.stream.Collectors, sun.net.httpserver.UnmodifiableHeaders, .Utils
HTTP request and response headers are represented by this class which implements the interface java.util.Map<java.lang.String, java.util.List <java.lang.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: 

HeaderName: value1
HeaderName: value2
All the normal java.util.Map methods are provided, but the following additional convenience methods are most likely to be used:

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

Field Summary

Modifier and TypeField and Description
pack-priv HashMap<String, List<String>>
map

Constructor Summary

AccessConstructor and Description
public
Headers()

Creates an empty instance of Headers.

public
Headers(Map<String, List<String>>
a map of header names and values
headers)

Creates a mutable Headers from the given headers with the same header names and values.

Method Summary

Modifier and TypeMethod and Description
public void
add(String
the header name
key, String
the value to add to the header
value)

Adds the given value to the list of headers for the given key.

public void
clear()

Implements java.util.Map.clear.

Removes all of the mappings from this map (optional operation).

public boolean
containsKey(Object key)

Implements java.util.Map.containsKey.

Returns true if this map contains a mapping for the specified key.

public boolean
containsValue(Object value)

Implements java.util.Map.containsValue.

Returns true if this map maps one or more keys to the specified value.

public Set<Map.Entry<String, List<String>>>
entrySet()

Implements java.util.Map.entrySet.

Returns a Set view of the mappings contained in this map.

public boolean
equals(Object o)

Overrides java.lang.Object.equals.

Implements java.util.Map.equals.

Compares the specified object with this map for equality.

public List<String>
get(Object key)

Implements java.util.Map.get.

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

public String

Returns:

the first String value associated with the key, or null if no mapping for the key exists
getFirst(String
the key to search for
key)

Returns the first value from the List of String values for the given key, or null if no mapping for the key exists.

public int
hashCode()

Overrides java.lang.Object.hashCode.

Implements java.util.Map.hashCode.

Returns the hash code value for this map.

public boolean
isEmpty()

Implements java.util.Map.isEmpty.

Returns true if this map contains no key-value mappings.

public Set<String>
keySet()

Implements java.util.Map.keySet.

Returns a Set view of the keys contained in this map.

private static String

Returns:

the normalized header name of the following form: the first character in upper-case, the rest in lower-case
normalize(String
an ASCII-encoded header name
key)

Returns the normalized header name of the following form: the first character in upper-case, the rest in lower-case.

public static Headers

Returns:

an immutable headers with the given name value pairs
of(String...
the list of name value pairs
headers)

Returns an immutable Headers with the given name value pairs as its set of headers.

public static Headers

Returns:

an immutable headers
of(Map<String, List<String>>
a map of header names and values
headers)

Returns an immutable Headers from the given headers with the same header names and values.

public List<String>
put(String key, List<String> value)

Implements java.util.Map.put.

Associates the specified value with the specified key in this map (optional operation).

public void
putAll(Map<? extends String, ? extends List<String>> t)

Implements java.util.Map.putAll.

Copies all of the mappings from the specified map to this map (optional operation).

public List<String>
remove(Object key)

Implements java.util.Map.remove.

Removes the mapping for a key from this map if it is present (optional operation).

public void
replaceAll(BiFunction<? super String, ? super List<String>, ? extends List<String>> function)

Overrides default java.util.Map.replaceAll.

Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception (optional operation).

public void
set(String
the header name
key, String
the header value to set
value)

Sets the given value as the sole header value for the given key.

public int
size()

Implements java.util.Map.size.

Returns the number of key-value mappings in this map.

public String
toString()

Overrides java.lang.Object.toString.

Returns a string representation of the object.

public Collection<List<String>>
values()

Implements java.util.Map.values.

Returns a Collection view of the values contained in this map.

Inherited from java.lang.Object:
clonefinalizegetClassnotifynotifyAllwaitwaitwait

Field Detail

mapback to summary
pack-priv HashMap<String, List<String>> map

Constructor Detail

Headersback to summary
public Headers()

Creates an empty instance of Headers.

Headersback to summary
public Headers(Map<String, List<String>> headers)

Creates a mutable Headers from the given headers with the same header names and values.

Parameters
headers:Map<String, List<String>>

a map of header names and values

Exceptions
NullPointerException:
if headers or any of its names or values are null, or if any value contains null.
Since
18

Method Detail

addback to summary
public void add(String key, String value)

Adds the given value to the list of headers for the given key. If the mapping does not already exist, then it is created.

Parameters
key:String

the header name

value:String

the value to add to the header

clearback to summary
public void clear()

Implements java.util.Map.clear.

Doc from java.util.Map.clear.

Removes all of the mappings from this map (optional operation). The map will be empty after this call returns.

Annotations
@Override
containsKeyback to summary
public boolean containsKey(Object key)

Implements java.util.Map.containsKey.

Doc from java.util.Map.containsKey.

Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains a mapping for a key k such that Objects.equals(key, k). (There can be at most one such mapping.)

Annotations
@Override
containsValueback to summary
public boolean containsValue(Object value)

Implements java.util.Map.containsValue.

Doc from java.util.Map.containsValue.

Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that Objects.equals(value, v). This operation will probably require time linear in the map size for most implementations of the Map interface.

Annotations
@Override
entrySetback to summary
public Set<Map.Entry<String, List<String>>> entrySet()

Implements java.util.Map.entrySet.

Doc from java.util.Map.entrySet.

Returns a Set 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 own remove operation, or through the setValue 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 the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Annotations
@Override
equalsback to summary
public boolean equals(Object o)

Overrides java.lang.Object.equals.

Implements java.util.Map.equals.

Doc from java.util.Map.equals.

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This ensures that the equals method works properly across different implementations of the Map interface.

Annotations
@Override
getback to summary
public List<String> get(Object key)

Implements java.util.Map.get.

Doc from java.util.Map.get.

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

More formally, if this map contains a mapping from a key k to a value v such that Objects.equals(key, k), then this method returns v; otherwise it returns null. (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 to null. The containsKey operation may be used to distinguish these two cases.

Annotations
@Override
getFirstback to summary
public String getFirst(String key)

Returns the first value from the List of String values for the given key, or null if no mapping for the key exists.

Parameters
key:String

the key to search for

Returns:String

the first String value associated with the key, or null if no mapping for the key exists

hashCodeback to summary
public int hashCode()

Overrides java.lang.Object.hashCode.

Implements java.util.Map.hashCode.

Doc from java.util.Map.hashCode.

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's entrySet() view. This ensures that m1.equals(m2) implies that m1.hashCode()==m2.hashCode() for any two maps m1 and m2, as required by the general contract of Object#hashCode.

Annotations
@Override
isEmptyback to summary
public boolean isEmpty()

Implements java.util.Map.isEmpty.

Doc from java.util.Map.isEmpty.

Returns true if this map contains no key-value mappings.

Annotations
@Override
keySetback to summary
public Set<String> keySet()

Implements java.util.Map.keySet.

Doc from java.util.Map.keySet.

Returns a Set 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 own remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

Annotations
@Override
normalizeback to summary
private static String normalize(String key)

Returns the normalized header name of the following form: the first character in upper-case, the rest in lower-case. The input header name is assumed to be encoded in ASCII.

Implementation Specification

This method is performance-sensitive; update with care.

Parameters
key:String

an ASCII-encoded header name

Returns:String

the normalized header name of the following form: the first character in upper-case, the rest in lower-case

Exceptions
NullPointerException:
on null key
IllegalArgumentException:
if key contains \r or \n
ofback to summary
public static Headers of(String... headers)

Returns an immutable Headers 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 supplied headers is empty, then an empty Headers is returned.

Parameters
headers:String[]

the list of name value pairs

Returns:Headers

an immutable headers with the given name value pairs

Exceptions
NullPointerException:
if headers or any of its elements are null.
IllegalArgumentException:
if the number of supplied strings is odd.
Since
18
ofback to summary
public static Headers of(Map<String, List<String>> headers)

Returns an immutable Headers from the given headers with the same header names and values.

Parameters
headers:Map<String, List<String>>

a map of header names and values

Returns:Headers

an immutable headers

Exceptions
NullPointerException:
if headers or any of its names or values are null, or if any value contains null.
Since
18
putback to summary
public List<String> put(String key, List<String> value)

Implements java.util.Map.put.

Doc from java.util.Map.put.

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 map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)

Annotations
@Override
putAllback to summary
public void putAll(Map<? extends String, ? extends List<String>> t)

Implements java.util.Map.putAll.

Doc from java.util.Map.putAll.

Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v 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.

Annotations
@Override
removeback to summary
public List<String> remove(Object key)

Implements java.util.Map.remove.

Doc from java.util.Map.remove.

Removes the mapping for a key from this map if it is present (optional operation). More formally, if this map contains a mapping from key k to value v such that Objects.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 to null.

The map will not contain a mapping for the specified key once the call returns.

Annotations
@Override
replaceAllback to summary
public void replaceAll(BiFunction<? super String, ? super List<String>, ? extends List<String>> function)

Overrides default java.util.Map.replaceAll.

Doc from java.util.Map.replaceAll.

Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception (optional operation). Exceptions thrown by the function are relayed to the caller.

Annotations
@Override
setback to summary
public void set(String key, String value)

Sets the given value as the sole header value for the given key. If the mapping does not already exist, then it is created.

Parameters
key:String

the header name

value:String

the header value to set

sizeback to summary
public int size()

Implements java.util.Map.size.

Doc from java.util.Map.size.

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Annotations
@Override
toStringback to summary
public String toString()

Overrides java.lang.Object.toString.

Doc from java.lang.Object.toString.

Returns a string representation of the object. Satisfying this method's contract implies a non-null result must be returned.

Annotations
@Override
valuesback to summary
public Collection<List<String>> values()

Implements java.util.Map.values.

Doc from java.util.Map.values.

Returns a Collection 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 own remove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Annotations
@Override