public class Headers extends Object implements Map<String,List<String>>
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 occurence 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 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 keyset(String,String) sets the given header field to the single value given
overwriting any existing values in the value list.
All methods in this class accept null values for keys and values. However, null
keys will never will be present in HTTP request headers, and will not be output/sent in response headers.
Null values can be represented as either a null entry for the key (i.e. the list is null) or
where the key has a list, but one (or more) of the list's values is null. Null values are output
as a header line containing the key but no associated value.
| Constructor and Description |
|---|
Headers() |
| Modifier and Type | Method and Description |
|---|---|
void |
add(String key,
String value)
adds the given value to the list of headers
for the given key.
|
void |
clear()
Removes all of the mappings from this map (optional operation).
|
boolean |
containsKey(Object key)
Returns true if this map contains a mapping for the specified
key.
|
boolean |
containsValue(Object value)
Returns true if this map maps one or more keys to the
specified value.
|
Set<Map.Entry<String,List<String>>> |
entrySet()
Returns a
Set view of the mappings contained in this map. |
boolean |
equals(Object o)
Indicates whether some other object is "equal to" this one.
|
List<String> |
get(Object key)
Returns the value to which the specified key is mapped,
or
null if this map contains no mapping for the key. |
String |
getFirst(String key)
returns the first value from the List of String values
for the given key (if at least one exists).
|
int |
hashCode()
Returns a hash code value for the object.
|
boolean |
isEmpty()
Returns true if this map contains no key-value mappings.
|
Set<String> |
keySet()
Returns a
Set view of the keys contained in this map. |
List<String> |
put(String key,
List<String> value)
Associates the specified value with the specified key in this map
(optional operation).
|
void |
putAll(Map<? extends String,? extends List<String>> t)
Copies all of the mappings from the specified map to this map
(optional operation).
|
List<String> |
remove(Object key)
Removes the mapping for a key from this map if it is present
(optional operation).
|
void |
set(String key,
String value)
sets the given value as the sole header value
for the given key.
|
int |
size()
Returns the number of key-value mappings in this map.
|
Collection<List<String>> |
values()
Returns a
Collection view of the values contained in this map. |
public int size()
java.util.Mappublic boolean isEmpty()
java.util.Mappublic boolean containsKey(Object key)
java.util.MapcontainsKey in interface Map<String,List<String>>key - key whose presence in this map is to be testedpublic boolean containsValue(Object value)
java.util.MapcontainsValue in interface Map<String,List<String>>value - value whose presence in this map is to be testedpublic List<String> get(Object key)
java.util.Mapnull 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 (key==null ? k==null :
key.equals(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.
public String getFirst(String key)
key - the key to search forpublic List<String> put(String key, List<String> value)
java.util.Mapm.containsKey(k) would return
true.)put in interface Map<String,List<String>>key - key with which the specified value is to be associatedvalue - value to be associated with the specified keypublic void add(String key, String value)
key - the header namevalue - the header value to add to the headerpublic void set(String key, String value)
key - the header namevalue - the header value to set.public List<String> remove(Object key)
java.util.Map(key==null ? k==null : key.equals(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.
public void putAll(Map<? extends String,? extends List<String>> t)
java.util.Mapput(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.public void clear()
java.util.Mappublic Set<String> keySet()
java.util.MapSet 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.public Collection<List<String>> values()
java.util.MapCollection 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.public Set<Map.Entry<String,List<String>>> entrySet()
java.util.MapSet 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.public boolean equals(Object o)
java.lang.Object
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode method, which states
that equal objects must have equal hash codes.
public int hashCode()
java.lang.ObjectHashMap.
The general contract of hashCode is:
hashCode method
must consistently return the same integer, provided no information
used in equals comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode method on each of
the two objects must produce the same integer result.
Object.equals(java.lang.Object)
method, then calling the hashCode method 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.
As much as is reasonably practical, the hashCode method defined by
class Object does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
JavaTM programming language.)
hashCode in interface Map<String,List<String>>hashCode in class ObjectObject.equals(java.lang.Object),
System.identityHashCode(java.lang.Object)
Copyright © 2005, 2014, Oracle and/or its affiliates. All rights reserved.