InvocationHandler
public class CompositeDataInvocationHandler extends Object implements InvocationHandler
An InvocationHandler
that forwards getter methods to a CompositeData
. If you have an interface that contains only getter methods (such as String getName()
or boolean isActive()
) then you can use this class in conjunction with the Proxy
class to produce an implementation of the interface where each getter returns the value of the corresponding item in a CompositeData
.
For example, suppose you have an interface like this:
and apublic interface NamedNumber { public int getNumber(); public String getName(); }
CompositeData
constructed like this: then you can construct an object implementingCompositeData cd = newCompositeDataSupport
( someCompositeType, new String[] {"number", "name"}, new Object[] {5, "five"} );
NamedNumber
and backed by the object cd
like this: A call toInvocationHandler handler = new CompositeDataInvocationHandler(cd); NamedNumber nn = (NamedNumber) Proxy.newProxyInstance(NamedNumber.class.getClassLoader(), new Class[] {NamedNumber.class}, handler);
nn.getNumber()
will then return 5. If the first letter of the property defined by a getter is a capital, then this handler will look first for an item in the CompositeData
beginning with a capital, then, if that is not found, for an item beginning with the corresponding lowercase letter or code point. For a getter called getNumber()
, the handler will first look for an item called Number
, then for number
. If the getter is called getnumber()
, then the item must be called number
.
If the method given to invoke
is the method boolean equals(Object)
inherited from Object
, then it will return true if and only if the argument is a Proxy
whose InvocationHandler
is also a
CompositeDataInvocationHandler
and whose backing
CompositeData
is equal (not necessarily identical) to this object's. If the method given to invoke
is the method int hashCode()
inherited from Object
, then it will return a value that is consistent with this definition of
equals
: if two objects are equal according to equals
, then they will have the same hashCode
.
Constructor | Description |
---|---|
CompositeDataInvocationHandler |
Construct a handler backed by the given
CompositeData . |
Modifier and Type | Method | Description |
---|---|---|
CompositeData |
getCompositeData() |
Return the CompositeData that was supplied to the constructor. |
Object |
invoke |
Processes a method invocation on a proxy instance and returns the result. |
public CompositeDataInvocationHandler(CompositeData compositeData)
Construct a handler backed by the given
CompositeData
.
compositeData
- the CompositeData
that will supply information to getters.IllegalArgumentException
- if compositeData
is null.public CompositeData getCompositeData()
CompositeData
that was supplied to the constructor.CompositeData
that this handler is backed by. This is never null.public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
InvocationHandler
invoke
in interface InvocationHandler
proxy
- the proxy instance that the method was invoked onmethod
- the Method
instance corresponding to the interface method invoked on the proxy instance. The declaring class of the Method
object will be the interface that the method was declared in, which may be a superinterface of the proxy interface that the proxy class inherits the method through.args
- an array of objects containing the values of the arguments passed in the method invocation on the proxy instance, or null
if interface method takes no arguments. Arguments of primitive types are wrapped in instances of the appropriate primitive wrapper class, such as java.lang.Integer
or java.lang.Boolean
.null
and the interface method's return type is primitive, then a NullPointerException
will be thrown by the method invocation on the proxy instance. If the value returned by this method is otherwise not compatible with the interface method's declared return type as described above, a ClassCastException
will be thrown by the method invocation on the proxy instance.Throwable
- the exception to throw from the method invocation on the proxy instance. The exception's type must be assignable either to any of the exception types declared in the throws
clause of the interface method or to the unchecked exception types java.lang.RuntimeException
or java.lang.Error
. If a checked exception is thrown by this method that is not assignable to any of the exception types declared in the throws
clause of the interface method, then an UndeclaredThrowableException
containing the exception that was thrown by this method will be thrown by the method invocation on the proxy instance.
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Documentation extracted from Debian's OpenJDK Development Kit package.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.management/javax/management/openmbean/CompositeDataInvocationHandler.html