public class ContextBase extends java.util.HashMap implements Context
Convenience base class for Context
implementations.
In addition to the minimal functionality required by the Context
interface, this class implements the recommended support for
Attribute-Property Transparency. This is implemented by
analyzing the available JavaBeans properties of this class (or its
subclass), exposes them as key-value pairs in the Map
,
with the key being the name of the property itself.
IMPLEMENTATION NOTE - Because empty
is a
read-only property defined by the Map
interface, it may not
be utilized as an attribute key or property name.
Modifier and Type | Class and Description |
---|---|
private class |
ContextBase.EntrySetImpl
Private implementation of
Set that implements the
semantics required for the value returned by entrySet() . |
private class |
ContextBase.EntrySetIterator
Private implementation of
Iterator for the
Set returned by entrySet() . |
private class |
ContextBase.MapEntryImpl
Private implementation of
Map.Entry for each item in
EntrySetImpl . |
private class |
ContextBase.ValuesImpl
Private implementation of
Collection that implements the
semantics required for the value returned by values() . |
private class |
ContextBase.ValuesIterator
Private implementation of
Iterator for the
Collection returned by values() . |
Modifier and Type | Field and Description |
---|---|
private java.util.Map |
descriptors
The
PropertyDescriptor s for all JavaBeans properties
of this Context implementation class, keyed by property name. |
private java.beans.PropertyDescriptor[] |
pd
The same
PropertyDescriptor s as an array. |
private static java.lang.Object |
singleton
Distinguished singleton value that is stored in the map for each
key that is actually a property.
|
private static java.lang.Object[] |
zeroParams
Zero-length array of parameter values for calling property getters.
|
Constructor and Description |
---|
ContextBase()
Default, no argument constructor.
|
ContextBase(java.util.Map map)
Initialize the contents of this
Context by copying the
values from the specified Map . |
Modifier and Type | Method and Description |
---|---|
void |
clear()
Override the default
Map behavior to clear all keys and
values except those corresponding to JavaBeans properties. |
boolean |
containsValue(java.lang.Object value)
Override the default
Map behavior to return
true if the specified value is present in either the
underlying Map or one of the local property values. |
private java.util.Iterator |
entriesIterator()
Return an
Iterator over the set of Map.Entry
objects representing our key-value pairs. |
private java.util.Map.Entry |
entry(java.lang.Object key)
Return a
Map.Entry for the specified key value, if it
is present; otherwise, return null . |
java.util.Set |
entrySet()
Override the default
Map behavior to return a
Set that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException . |
java.lang.Object |
get(java.lang.Object key)
Override the default
Map behavior to return the value
of a local property if the specified key matches a local property name. |
private void |
initialize()
Customize the contents of our underlying
Map so that
it contains keys corresponding to all of the JavaBeans properties of
the Context implementation class. |
boolean |
isEmpty()
Override the default
Map behavior to return
true if the underlying Map only contains
key-value pairs for local properties (if any). |
java.util.Set |
keySet()
Override the default
Map behavior to return a
Set that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException . |
java.lang.Object |
put(java.lang.Object key,
java.lang.Object value)
Override the default
Map behavior to set the value
of a local property if the specified key matches a local property name. |
void |
putAll(java.util.Map map)
Override the default
Map behavior to call the
put() method individually for each key-value pair
in the specified Map . |
private java.lang.Object |
readProperty(java.beans.PropertyDescriptor descriptor)
Get and return the value for the specified property.
|
private boolean |
remove(java.util.Map.Entry entry)
Remove the specified key-value pair, if it exists, and return
true . |
java.lang.Object |
remove(java.lang.Object key)
Override the default
Map behavior to throw
UnsupportedOperationException on any attempt to
remove a key that is the name of a local property. |
java.util.Collection |
values()
Override the default
Map behavior to return a
Collection that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException . |
private java.util.Iterator |
valuesIterator()
Return an
Iterator over the set of values in this
Map . |
private void |
writeProperty(java.beans.PropertyDescriptor descriptor,
java.lang.Object value)
Set the value for the specified property.
|
clone, compute, computeIfAbsent, computeIfPresent, containsKey, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll, size
private transient java.util.Map descriptors
The PropertyDescriptor
s for all JavaBeans properties
of this Context
implementation class, keyed by property name.
This collection is allocated only if there are any JavaBeans
properties.
private transient java.beans.PropertyDescriptor[] pd
The same PropertyDescriptor
s as an array.
private static java.lang.Object singleton
Distinguished singleton value that is stored in the map for each
key that is actually a property. This value is used to ensure that
equals()
comparisons will always fail.
private static java.lang.Object[] zeroParams
Zero-length array of parameter values for calling property getters.
public ContextBase()
public ContextBase(java.util.Map map)
Initialize the contents of this Context
by copying the
values from the specified Map
. Any keys in map
that correspond to local properties will cause the setter method for
that property to be called.
map
- Map whose key-value pairs are addedjava.lang.IllegalArgumentException
- if an exception is thrown
writing a local property valuejava.lang.UnsupportedOperationException
- if a local property does not
have a write method.public void clear()
Override the default Map
behavior to clear all keys and
values except those corresponding to JavaBeans properties.
clear
in interface java.util.Map
clear
in class java.util.HashMap
public boolean containsValue(java.lang.Object value)
Override the default Map
behavior to return
true
if the specified value is present in either the
underlying Map
or one of the local property values.
containsValue
in interface java.util.Map
containsValue
in class java.util.HashMap
value
- the value look for in the context.true
if found in this context otherwise
false
.java.lang.IllegalArgumentException
- if a property getter
throws an exceptionpublic java.util.Set entrySet()
Override the default Map
behavior to return a
Set
that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException
.
entrySet
in interface java.util.Map
entrySet
in class java.util.HashMap
public java.lang.Object get(java.lang.Object key)
Override the default Map
behavior to return the value
of a local property if the specified key matches a local property name.
IMPLEMENTATION NOTE - If the specified
key
identifies a write-only property, null
will arbitrarily be returned, in order to avoid difficulties implementing
the contracts of the Map
interface.
get
in interface java.util.Map
get
in class java.util.HashMap
key
- Key of the value to be returnedjava.lang.IllegalArgumentException
- if an exception is thrown
reading this local property valuejava.lang.UnsupportedOperationException
- if this local property does not
have a read method.public boolean isEmpty()
Override the default Map
behavior to return
true
if the underlying Map
only contains
key-value pairs for local properties (if any).
isEmpty
in interface java.util.Map
isEmpty
in class java.util.HashMap
true
if this Context is empty, otherwise
false
.public java.util.Set keySet()
Override the default Map
behavior to return a
Set
that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException
.
keySet
in interface java.util.Map
keySet
in class java.util.HashMap
public java.lang.Object put(java.lang.Object key, java.lang.Object value)
Override the default Map
behavior to set the value
of a local property if the specified key matches a local property name.
put
in interface java.util.Map
put
in class java.util.HashMap
key
- Key of the value to be stored or replacedvalue
- New value to be storedjava.lang.IllegalArgumentException
- if an exception is thrown
reading or wrting this local property valuejava.lang.UnsupportedOperationException
- if this local property does not
have both a read method and a write methodpublic void putAll(java.util.Map map)
Override the default Map
behavior to call the
put()
method individually for each key-value pair
in the specified Map
.
putAll
in interface java.util.Map
putAll
in class java.util.HashMap
map
- Map
containing key-value pairs to store
(or replace)java.lang.IllegalArgumentException
- if an exception is thrown
reading or wrting a local property valuejava.lang.UnsupportedOperationException
- if a local property does not
have both a read method and a write methodpublic java.lang.Object remove(java.lang.Object key)
Override the default Map
behavior to throw
UnsupportedOperationException
on any attempt to
remove a key that is the name of a local property.
remove
in interface java.util.Map
remove
in class java.util.HashMap
key
- Key to be removedjava.lang.UnsupportedOperationException
- if the specified
key
matches the name of a local propertypublic java.util.Collection values()
Override the default Map
behavior to return a
Collection
that meets the specified default behavior except
for attempts to remove the key for a property of the Context
implementation class, which will throw
UnsupportedOperationException
.
values
in interface java.util.Map
values
in class java.util.HashMap
private java.util.Iterator entriesIterator()
Return an Iterator
over the set of Map.Entry
objects representing our key-value pairs.
private java.util.Map.Entry entry(java.lang.Object key)
Return a Map.Entry
for the specified key value, if it
is present; otherwise, return null
.
key
- Attribute key or property nameprivate void initialize()
Customize the contents of our underlying Map
so that
it contains keys corresponding to all of the JavaBeans properties of
the Context
implementation class.
java.lang.IllegalArgumentException
- if an exception is thrown
writing this local property valuejava.lang.UnsupportedOperationException
- if this local property does not
have a write method.private java.lang.Object readProperty(java.beans.PropertyDescriptor descriptor)
Get and return the value for the specified property.
descriptor
- PropertyDescriptor
for the
specified propertyjava.lang.IllegalArgumentException
- if an exception is thrown
reading this local property valuejava.lang.UnsupportedOperationException
- if this local property does not
have a read method.private boolean remove(java.util.Map.Entry entry)
Remove the specified key-value pair, if it exists, and return
true
. If this pair does not exist, return
false
.
entry
- Key-value pair to be removedjava.lang.UnsupportedOperationException
- if the specified key
identifies a property instead of an attributeprivate java.util.Iterator valuesIterator()
Return an Iterator
over the set of values in this
Map
.
private void writeProperty(java.beans.PropertyDescriptor descriptor, java.lang.Object value)
Set the value for the specified property.
descriptor
- PropertyDescriptor
for the
specified propertyvalue
- The new value for this property (must be of the
correct type)java.lang.IllegalArgumentException
- if an exception is thrown
writing this local property valuejava.lang.UnsupportedOperationException
- if this local property does not
have a write method.