Class CompositeDataInvocationHandler
- All Implemented Interfaces:
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:
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 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.
- Since:
- 1.6
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Constructor Summary
ConstructorsConstructorDescriptionCompositeDataInvocationHandler(CompositeData compositeData) Construct a handler backed by the givenCompositeData. -
Method Summary
Modifier and TypeMethodDescriptionReturn theCompositeDatathat was supplied to the constructor.Processes a method invocation on a proxy instance and returns the result.
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Constructor Details
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CompositeDataInvocationHandler
Construct a handler backed by the given
CompositeData.- Parameters:
compositeData- theCompositeDatathat will supply information to getters.- Throws:
IllegalArgumentException- ifcompositeDatais null.
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Method Details
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getCompositeData
Return theCompositeDatathat was supplied to the constructor.- Returns:
- the
CompositeDatathat this handler is backed by. This is never null.
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invoke
Description copied from interface:InvocationHandlerProcesses a method invocation on a proxy instance and returns the result. This method will be invoked on an invocation handler when a method is invoked on a proxy instance that it is associated with.- Specified by:
invokein interfaceInvocationHandler- Parameters:
proxy- the proxy instance that the method was invoked onmethod- theMethodinstance corresponding to the interface method invoked on the proxy instance. The declaring class of theMethodobject 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, ornullif interface method takes no arguments. Arguments of primitive types are wrapped in instances of the appropriate primitive wrapper class, such asjava.lang.Integerorjava.lang.Boolean.- Returns:
- the value to return from the method invocation on the
proxy instance. If the declared return type of the interface
method is a primitive type, then the value returned by
this method must be an instance of the corresponding primitive
wrapper class; otherwise, it must be a type assignable to the
declared return type. If the value returned by this method is
nulland the interface method's return type is primitive, then aNullPointerExceptionwill 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, aClassCastExceptionwill be thrown by the method invocation on the proxy instance. - Throws:
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 thethrowsclause of the interface method or to the unchecked exception typesjava.lang.RuntimeExceptionorjava.lang.Error. If a checked exception is thrown by this method that is not assignable to any of the exception types declared in thethrowsclause of the interface method, then anUndeclaredThrowableExceptioncontaining the exception that was thrown by this method will be thrown by the method invocation on the proxy instance.- See Also:
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