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java.lang.Objectorg.apache.commons.attributes.Attributes
public class Attributes
API for accessing attributes.
RepositoryError
or subclasses thereof.
This Error is thrown if an attribute repository can not be loaded for some Exceptional
reason.
Error
s instead of Exception
s.
This rationale behind this is that:
If a parameter to a method may not be null, and a null is passed to the
method, a NullPointerException
will be thrown, with the
parameter name in the message.
Rationale for using this instead of IllegalArgumentException
is that it is more precise - the reference was null.
The process of loading attributes for a class is a (relatively) time-consuming process, as it involves some dynamic linking in the form of inheritable attributes, a lot of reflection and so on. However, once loaded the attributes are cached, so repeated access to them are fast. But despite this the process of finding one attribute of a given type or such operations does involve some iteration of HashSets that runs in linear time in the number of attributes associated with the program element, and you should avoid accessing attributes in your innermost loops if you can avoid it. For example, instead of:
Class myClass = ...;
for (int i = 0; i < 10000; i++) {
if (Attributes.hasAttributeType (myClass, MyAttribute.class)) {
doThis(myClass);
} else {
doThat(myClass);
}
}
do:
Class myClass = ...;
boolean shouldDoThis = Attributes.hasAttributeType (myClass, MyAttribute.class);
for (int i = 0; i < 10000; i++) {
if (shouldDoThis) {
doThis(myClass);
} else {
doThat(myClass);
}
}
if the loop should run at maximum speed.
Field Summary | |
---|---|
private static java.util.Map |
classRepositories
A cache of attribute repositories. |
private static java.util.List |
initList
List used to keep track of the initialization list in getCachedRepository. |
Constructor Summary | |
---|---|
Attributes()
|
Method Summary | |
---|---|
static java.lang.Object |
getAttribute(java.lang.Class clazz,
java.lang.Class attributeClass)
Get one attributes of a given type from a class. |
private static java.lang.Object |
getAttribute(java.util.Collection attrs,
java.lang.Class attributeClass)
Selects from a collection of attributes one attribute with a given class. |
static java.lang.Object |
getAttribute(java.lang.reflect.Constructor constructor,
java.lang.Class attributeClass)
Get one attributes of a given type from a constructor. |
static java.lang.Object |
getAttribute(java.lang.reflect.Field field,
java.lang.Class attributeClass)
Get one attributes of a given type from a field. |
static java.lang.Object |
getAttribute(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Get one attributes of a given type from a method. |
static java.util.Collection |
getAttributes(java.lang.Class clazz)
Gets all attributes for a class. |
static java.util.Collection |
getAttributes(java.lang.Class clazz,
java.lang.Class attributeClass)
Get all attributes of a given type from a class. |
private static java.util.Collection |
getAttributes(java.util.Collection attrs,
java.lang.Class attributeClass)
Selects from a collection of attributes only those with a given class. |
static java.util.Collection |
getAttributes(java.lang.reflect.Constructor constructor)
Gets all attributes for a constructor. |
static java.util.Collection |
getAttributes(java.lang.reflect.Constructor constructor,
java.lang.Class attributeClass)
Get all attributes of a given type from a constructor. |
static java.util.Collection |
getAttributes(java.lang.reflect.Field field)
Gets all attributes for a field. |
static java.util.Collection |
getAttributes(java.lang.reflect.Field field,
java.lang.Class attributeClass)
Get all attributes of a given type from a field. |
static java.util.Collection |
getAttributes(java.lang.reflect.Method method)
Gets all attributes for a method. |
static java.util.Collection |
getAttributes(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Get all attributes of a given type from a method. |
private static CachedRepository |
getCachedRepository(java.lang.Class clazz)
|
static java.lang.Object |
getParameterAttribute(java.lang.reflect.Constructor constructor,
int parameter,
java.lang.Class attributeClass)
Get one attributes of a given type from a constructor's parameter. |
static java.lang.Object |
getParameterAttribute(java.lang.reflect.Method method,
int parameter,
java.lang.Class attributeClass)
Get one attributes of a given type from a parameter. |
static java.util.Collection |
getParameterAttributes(java.lang.reflect.Constructor constructor,
int parameter)
Gets all attributes for a parameter of a constructor. |
static java.util.Collection |
getParameterAttributes(java.lang.reflect.Constructor constructor,
int parameter,
java.lang.Class attributeClass)
Get all attributes of a given type from a method's parameter. |
static java.util.Collection |
getParameterAttributes(java.lang.reflect.Method method,
int parameter)
Gets all attributes for a parameter of a method. |
static java.util.Collection |
getParameterAttributes(java.lang.reflect.Method method,
int parameter,
java.lang.Class attributeClass)
Get all attributes of a given type from a method's parameter. |
static java.lang.Object |
getReturnAttribute(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Get one attributes of a given type from a method's return value. |
static java.util.Collection |
getReturnAttributes(java.lang.reflect.Method method)
Gets all attributes for the return value of a method. |
static java.util.Collection |
getReturnAttributes(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Get all attributes of a given type from a method's return value. |
static boolean |
hasAttribute(java.lang.Class clazz,
java.lang.Object attribute)
Tests if a class has an attribute. |
private static boolean |
hasAttribute(java.util.Collection attrs,
java.lang.Object attribute)
Convenience function to test whether a collection of attributes contain an attribute. |
static boolean |
hasAttribute(java.lang.reflect.Constructor constructor,
java.lang.Object attribute)
Tests if a constructor has an attribute. |
static boolean |
hasAttribute(java.lang.reflect.Field field,
java.lang.Object attribute)
Tests if a field has an attribute. |
static boolean |
hasAttribute(java.lang.reflect.Method method,
java.lang.Object attribute)
Tests if a method has an attribute. |
static boolean |
hasAttributeType(java.lang.Class clazz,
java.lang.Class attributeClass)
Tests if a class has an attribute of a given type. |
private static boolean |
hasAttributeType(java.util.Collection attrs,
java.lang.Class attributeClass)
Convenience function to test whether a collection of attributes contain an attribute of a given class. |
static boolean |
hasAttributeType(java.lang.reflect.Constructor constructor,
java.lang.Class attributeClass)
Tests if a constructor has an attribute of a given type. |
static boolean |
hasAttributeType(java.lang.reflect.Field field,
java.lang.Class attributeClass)
Tests if a field has an attribute of a given type. |
static boolean |
hasAttributeType(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Tests if a method has an attribute of a given type. |
static boolean |
hasParameterAttribute(java.lang.reflect.Constructor constructor,
int parameter,
java.lang.Object attribute)
Tests if a constructor's parameter has an attribute. |
static boolean |
hasParameterAttribute(java.lang.reflect.Method method,
int parameter,
java.lang.Object attribute)
Tests if a method's parameter has an attribute. |
static boolean |
hasParameterAttributeType(java.lang.reflect.Constructor constructor,
int parameter,
java.lang.Class attributeClass)
Tests if a constructor's parameter has an attribute of a given type. |
static boolean |
hasParameterAttributeType(java.lang.reflect.Method method,
int parameter,
java.lang.Class attributeClass)
Tests if a method's parameter has an attribute of a given type. |
static boolean |
hasReturnAttribute(java.lang.reflect.Method method,
java.lang.Object attribute)
Tests if a method's return value has an attribute. |
static boolean |
hasReturnAttributeType(java.lang.reflect.Method method,
java.lang.Class attributeClass)
Tests if a method's return value has an attribute of a given type. |
static void |
setAttributes(RuntimeAttributeRepository repo)
Set attributes for a given class. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
private static final java.util.Map classRepositories
class1 == class2
. Also, (class1.equals(class2)) == (class1 ==
class2)
. This means that a once a Class reference has been garbage-collected,
it can't be re-created. Thus we can treat the cache map as a normal map - the only
entries that will ever disappear are those we can't look up anyway because we
can't ever create the key for them!
Also, this will keep the cache from growing too big in environments where classes are loaded and unloaded all the time (i.e. application servers).
private static java.util.List initList
Constructor Detail |
---|
public Attributes()
Method Detail |
---|
private static CachedRepository getCachedRepository(java.lang.Class clazz) throws RepositoryError, CircularDependencyError
RepositoryError
CircularDependencyError
private static java.lang.Object getAttribute(java.util.Collection attrs, java.lang.Class attributeClass) throws MultipleAttributesError
attrs
- the collection of attribute instances to select from.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.public static java.lang.Object getAttribute(java.lang.Class clazz, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
clazz
- the class. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
RepositoryError
public static java.lang.Object getAttribute(java.lang.reflect.Field field, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
field
- the field. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
RepositoryError
public static java.lang.Object getAttribute(java.lang.reflect.Constructor constructor, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
constructor
- the constructor. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
RepositoryError
public static java.lang.Object getAttribute(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
method
- the method. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
RepositoryError
public static java.lang.Object getParameterAttribute(java.lang.reflect.Method method, int parameter, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
method
- the method. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.parameter
- index of the parameter in the method's parameter list.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the method accepts.
RepositoryError
public static java.lang.Object getParameterAttribute(java.lang.reflect.Constructor constructor, int parameter, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
constructor
- the constructor. May not be null
.parameter
- index of the parameter in the method's parameter list.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the constructor accepts.
RepositoryError
public static java.lang.Object getReturnAttribute(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError, MultipleAttributesError
method
- the method. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
null
of none could be found.
MultipleAttributesError
- if the collection contains more than one
instance of the specified class.
RepositoryError
public static java.util.Collection getAttributes(java.lang.Class clazz) throws RepositoryError
clazz
- the class. May not be null
.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Method method) throws RepositoryError
method
- the method. May not be null
.
RepositoryError
public static java.util.Collection getParameterAttributes(java.lang.reflect.Method method, int parameter) throws RepositoryError
method
- the method. May not be null
.parameter
- the index of the parameter in the method's parameter list.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the method accepts.
RepositoryError
public static java.util.Collection getParameterAttributes(java.lang.reflect.Constructor constructor, int parameter) throws RepositoryError
constructor
- the constructor. May not be null
.parameter
- the index of the parameter in the constructor's parameter list.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the constructor accepts.
RepositoryError
public static java.util.Collection getReturnAttributes(java.lang.reflect.Method method) throws RepositoryError
method
- the method. May not be null
.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Field field) throws RepositoryError
field
- the field. May not be null
.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Constructor constructor) throws RepositoryError
constructor
- the constructor. May not be null
.
RepositoryError
private static java.util.Collection getAttributes(java.util.Collection attrs, java.lang.Class attributeClass)
public static java.util.Collection getAttributes(java.lang.Class clazz, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
clazz
- the class. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Field field, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
field
- the field. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Constructor constructor, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
constructor
- the constructor. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
RepositoryError
public static java.util.Collection getAttributes(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
method
- the method. May not be null
.attributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
RepositoryError
public static java.util.Collection getParameterAttributes(java.lang.reflect.Method method, int parameter, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
method
- the method. May not be null
.parameter
- index of the parameter in the method's parameter listattributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the method accepts.
RepositoryError
public static java.util.Collection getParameterAttributes(java.lang.reflect.Constructor constructor, int parameter, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
constructor
- the constructor. May not be null
.parameter
- index of the parameter in the constructor's parameter listattributeClass
- the type of attribute. May be null
, but this will not match anything.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the constructor accepts.
RepositoryError
public static java.util.Collection getReturnAttributes(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError
o.getClass() == attributeClass
.
method
- the methodattributeClass
- the type of attribute wanted. May be null
, but this will not match anything.
RepositoryError
private static boolean hasAttributeType(java.util.Collection attrs, java.lang.Class attributeClass)
public static boolean hasAttributeType(java.lang.Class clazz, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
clazz
- the class. May not be null
.attributeClass
- the type of attribute. May be null
, but this will not match anything.
RepositoryError
public static boolean hasAttributeType(java.lang.reflect.Field field, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
field
- the field. May not be null
.attributeClass
- the type of attribute. May be null
, but this will not match anything.
RepositoryError
public static boolean hasAttributeType(java.lang.reflect.Constructor constructor, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
constructor
- the constructor. May not be null
.attributeClass
- the type of attribute. May be null
, but this will not match anything.
RepositoryError
public static boolean hasAttributeType(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
method
- the method. May not be null
.attributeClass
- the type of attribute. May be null
, but this will not match anything.
RepositoryError
public static boolean hasParameterAttributeType(java.lang.reflect.Method method, int parameter, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
method
- the method. May not be null
.parameter
- the index of the parameter in the method's parameter list.attributeClass
- the type of attribute. May be null
, but this will not match anything.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the method accepts.
RepositoryError
public static boolean hasParameterAttributeType(java.lang.reflect.Constructor constructor, int parameter, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
constructor
- the constructor. May not be null
.parameter
- the index of the parameter in the constructor's parameter list.attributeClass
- the type of attribute. May be null
, but this will not match anything.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the constructor accepts.
RepositoryError
public static boolean hasReturnAttributeType(java.lang.reflect.Method method, java.lang.Class attributeClass) throws RepositoryError
attr
such that attr.getClass() == attributeClass
?
method
- the method. May not be null
.attributeClass
- the type of attribute. May be null
, but this will not match anything.
RepositoryError
private static boolean hasAttribute(java.util.Collection attrs, java.lang.Object attribute) throws RepositoryError
RepositoryError
public static boolean hasAttribute(java.lang.Class clazz, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
clazz
- the class. May not be null
.attribute
- the attribute to compare to.
RepositoryError
public static boolean hasAttribute(java.lang.reflect.Field field, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
field
- the field. May not be null
.attribute
- the attribute to compare to.
RepositoryError
public static boolean hasAttribute(java.lang.reflect.Constructor constructor, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
constructor
- the constructor. May not be null
.attribute
- the attribute to compare to.
RepositoryError
public static boolean hasAttribute(java.lang.reflect.Method method, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
method
- the method. May not be null
.attribute
- the attribute to compare to.
RepositoryError
public static boolean hasParameterAttribute(java.lang.reflect.Method method, int parameter, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
method
- the method. May not be null
.parameter
- the index of the parameter in the method's parameter list.attribute
- the attribute to compare to.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the method accepts.
RepositoryError
public static boolean hasParameterAttribute(java.lang.reflect.Constructor constructor, int parameter, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
constructor
- the constructor. May not be null
.parameter
- the index of the parameter in the constructor's parameter list.attribute
- the attribute to compare to.
ParameterIndexOutOfBoundsException
- if the parameter index is < 0 or greater than the number
of parameters the constructor accepts.
RepositoryError
public static boolean hasReturnAttribute(java.lang.reflect.Method method, java.lang.Object attribute) throws RepositoryError
attr
such that attr.equals(attribute)
?
method
- the method. May not be null
.attribute
- the attribute to compare to.
RepositoryError
public static void setAttributes(RuntimeAttributeRepository repo) throws java.lang.IllegalStateException
repo
- The repository. The repository will be sealed before any attributes are
set. This to guarantee that the repository remains constant
during setting.
java.lang.IllegalStateException
- if the class whose attributes are defined already have
attributes defined for it (even if it has no attributes).
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