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Java Standard Edition (SE)



Class CompositeDataInvocationHandler

  • All Implemented Interfaces:

    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:

       public interface NamedNumber {
           public int getNumber();
           public String getName();
    and a CompositeData constructed like this:
       CompositeData cd =
           new CompositeDataSupport(
               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)
                                  new Class[] {NamedNumber.class},
    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.

    • Constructor Detail

      • CompositeDataInvocationHandler

        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.
    • Method Detail

      • getCompositeData

        public CompositeData getCompositeData()
        Return the CompositeData that was supplied to the constructor.
        the CompositeData that this handler is backed by. This is never null.
      • invoke

        public Object invoke(Object proxy,
                             Method method,
                             Object[] args)
                      throws Throwable
        Description copied from interface: InvocationHandler
        Processes 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:
        invoke in interface InvocationHandler
        proxy - the proxy instance that the method was invoked on
        method - 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.
        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 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.
        See Also:


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