CompositeDataInvocationHandler (Java Platform SE 8 ) (original) (raw)

An InvocationHandler that forwards getter methods to aCompositeData. If you have an interface that contains only getter methods (such as String getName() orboolean 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:

public interface NamedNumber { public int getNumber(); public String getName(); }

and a CompositeData constructed like this:

CompositeData cd = new CompositeDataSupport( someCompositeType, new String[] {"number", "name"}, new Object[] {5, "five"} );

then you can construct an object implementing NamedNumber and backed by the object cd like this:

InvocationHandler handler = new CompositeDataInvocationHandler(cd); NamedNumber nn = (NamedNumber) Proxy.newProxyInstance(NamedNumber.class.getClassLoader(), new Class[] {NamedNumber.class}, handler);

A call to 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 theCompositeData 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 fornumber. If the getter is called getnumber(), then the item must be called number.

If the method given to invoke is the methodboolean 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 methodint 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.