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RemoteObjectInvocationHandler.javaAPI DocJava SE 6 API8759Tue Jun 10 00:25:44 BST 2008java.rmi.server

RemoteObjectInvocationHandler

public class RemoteObjectInvocationHandler extends RemoteObject implements InvocationHandler
An implementation of the InvocationHandler interface for use with Java Remote Method Invocation (Java RMI). This invocation handler can be used in conjunction with a dynamic proxy instance as a replacement for a pregenerated stub class.

Applications are not expected to use this class directly. A remote object exported to use a dynamic proxy with {@link UnicastRemoteObject} or {@link Activatable} has an instance of this class as that proxy's invocation handler.

version
1.5, 05/11/17
author
Ann Wollrath
since
1.5

Fields Summary
private static final long
serialVersionUID
private static final MethodToHash_Maps
methodToHash_Maps
A weak hash map, mapping classes to weak hash maps that map method objects to method hashes.
Constructors Summary
public RemoteObjectInvocationHandler(RemoteRef ref)
Creates a new RemoteObjectInvocationHandler constructed with the specified RemoteRef.

param
ref the remote ref
throws
NullPointerException if ref is null


                             
       
	super(ref);
	if (ref == null) {
	    throw new NullPointerException();
	}
    
Methods Summary
private static longgetMethodHash(java.lang.reflect.Method method)
Returns the method hash for the specified method. Subsequent calls to "getMethodHash" passing the same method argument should be faster since this method caches internally the result of the method to method hash mapping. The method hash is calculated using the "computeMethodHash" method.

param
method the remote method
return
the method hash for the specified method

	return methodToHash_Maps.get(method.getDeclaringClass()).get(method);
    
public java.lang.Objectinvoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)
Processes a method invocation made on the encapsulating proxy instance, proxy, and returns the result.

RemoteObjectInvocationHandler implements this method as follows:

If method is one of the following methods, it is processed as described below:

  • {@link Object#hashCode Object.hashCode}: Returns the hash code value for the proxy.
  • {@link Object#equals Object.equals}: Returns true if the argument (args[0]) is an instance of a dynamic proxy class and this invocation handler is equal to the invocation handler of that argument, and returns false otherwise.
  • {@link Object#toString Object.toString}: Returns a string representation of the proxy.

Otherwise, a remote call is made as follows:

  • If proxy is not an instance of the interface {@link Remote}, then an {@link IllegalArgumentException} is thrown.
  • Otherwise, the {@link RemoteRef#invoke invoke} method is invoked on this invocation handler's RemoteRef, passing proxy, method, args, and the method hash (defined in section 8.3 of the "Java Remote Method Invocation (RMI) Specification") for method, and the result is returned.
  • If an exception is thrown by RemoteRef.invoke and that exception is a checked exception that is not assignable to any exception in the throws clause of the method implemented by the proxy's class, then that exception is wrapped in an {@link UnexpectedException} and the wrapped exception is thrown. Otherwise, the exception thrown by invoke is thrown by this method.

The semantics of this method are unspecified if the arguments could not have been produced by an instance of some valid dynamic proxy class containing this invocation handler.

param
proxy the proxy instance that the method was invoked on
param
method the Method instance corresponding to the interface method invoked on the proxy instance
param
args an array of objects containing the values of the arguments passed in the method invocation on the proxy instance, or null if the method takes no arguments
return
the value to return from the method invocation on the proxy instance
throws
Throwable the exception to throw from the method invocation on the proxy instance
see

	if (method.getDeclaringClass() == Object.class) {
	    return invokeObjectMethod(proxy, method, args);
	} else {
	    return invokeRemoteMethod(proxy, method, args);
	}
    
private java.lang.ObjectinvokeObjectMethod(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)
Handles java.lang.Object methods.

	String name = method.getName();

	if (name.equals("hashCode")) {
	    return hashCode();

	} else if (name.equals("equals")) {
	    Object obj = args[0];
	    return
		proxy == obj ||
		(obj != null &&
		 Proxy.isProxyClass(obj.getClass()) &&
		 equals(Proxy.getInvocationHandler(obj)));

	} else if (name.equals("toString")) {
	    return proxyToString(proxy);

	} else {
	    throw new IllegalArgumentException(
		"unexpected Object method: " + method);
	}
    
private java.lang.ObjectinvokeRemoteMethod(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args)
Handles remote methods.

	try {
	    if (!(proxy instanceof Remote)) {
		throw new IllegalArgumentException(
		    "proxy not Remote instance");
	    }
	    return ref.invoke((Remote) proxy, method, args,
			      getMethodHash(method));
	} catch (Exception e) {
	    if (!(e instanceof RuntimeException)) {
		Class<?> cl = proxy.getClass();
		try {
		    method = cl.getMethod(method.getName(),
					  method.getParameterTypes());
		} catch (NoSuchMethodException nsme) {
		    throw (IllegalArgumentException)
			new IllegalArgumentException().initCause(nsme);
		}
		Class<?> thrownType = e.getClass();
		for (Class<?> declaredType : method.getExceptionTypes()) {
		    if (declaredType.isAssignableFrom(thrownType)) {
			throw e;
		    }
		}
		e = new UnexpectedException("unexpected exception", e);
	    }
	    throw e;
	}
    
private java.lang.StringproxyToString(java.lang.Object proxy)
Returns a string representation for a proxy that uses this invocation handler.

	Class<?>[] interfaces = proxy.getClass().getInterfaces();
	if (interfaces.length == 0) {
	    return "Proxy[" + this + "]";
	}
	String iface = interfaces[0].getName();
	if (iface.equals("java.rmi.Remote") && interfaces.length > 1) {
	    iface = interfaces[1].getName();
	}
	int dot = iface.lastIndexOf('.");
	if (dot >= 0) {
	    iface = iface.substring(dot + 1);
	}
	return "Proxy[" + iface + "," + this + "]";
    
private voidreadObjectNoData()

throws
InvalidObjectException unconditionally

        throw new InvalidObjectException("no data in stream; class: " +
                                         this.getClass().getName());