jndirmiclientinterceptor.java

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		if (getServiceInterface() != null && Remote.class.isAssignableFrom(getServiceInterface())) {
			stub = PortableRemoteObject.narrow(stub, getServiceInterface());
		}
		if (!(stub instanceof Remote)) {
			throw new NamingException("Located RMI stub of class [" + stub.getClass().getName() +
					"], with JNDI name [" + getJndiName() + "], does not implement interface [java.rmi.Remote]");
		}
		return (Remote) stub;
	}

	/**
	 * Return the RMI stub to use. Called for each invocation.
	 * <p>The default implementation returns the stub created on initialization,
	 * if any. Else, it invokes {@link #lookupStub} to get a new stub for
	 * each invocation. This can be overridden in subclasses, for example in
	 * order to cache a stub for a given amount of time before recreating it,
	 * or to test the stub whether it is still alive.
	 * @return the RMI stub to use for an invocation
	 * @throws NamingException if stub creation failed
	 */
	protected Remote getStub() throws NamingException {
		if (!this.cacheStub || (this.lookupStubOnStartup && !this.refreshStubOnConnectFailure)) {
			return (this.cachedStub != null ? this.cachedStub : lookupStub());
		}
		else {
			synchronized (this) {
				if (this.cachedStub == null) {
					this.cachedStub = lookupStub();
				}
				return this.cachedStub;
			}
		}
	}


	/**
	 * Fetches an RMI stub and delegates to {@link #doInvoke}.
	 * If configured to refresh on connect failure, it will call
	 * {@link #refreshAndRetry} on corresponding RMI exceptions.
	 * @see #getStub
	 * @see #doInvoke
	 * @see #refreshAndRetry
	 * @see java.rmi.ConnectException
	 * @see java.rmi.ConnectIOException
	 * @see java.rmi.NoSuchObjectException
	 */
	public Object invoke(MethodInvocation invocation) throws Throwable {
		Remote stub = null;
		try {
			stub = getStub();
		}
		catch (Throwable ex) {
			throw new RemoteLookupFailureException("JNDI lookup for RMI service [" + getJndiName() + "] failed", ex);
		}
		try {
			return doInvoke(invocation, stub);
		}
		catch (RemoteConnectFailureException ex) {
			return handleRemoteConnectFailure(invocation, ex);
		}
		catch (RemoteException ex) {
			if (isConnectFailure(ex)) {
				return handleRemoteConnectFailure(invocation, ex);
			}
			else {
				throw ex;
			}
		}
	}

	/**
	 * Determine whether the given RMI exception indicates a connect failure.
	 * <p>The default implementation delegates to
	 * {@link RmiClientInterceptorUtils#isConnectFailure}.
	 * @param ex the RMI exception to check
	 * @return whether the exception should be treated as connect failure
	 */
	protected boolean isConnectFailure(RemoteException ex) {
		return RmiClientInterceptorUtils.isConnectFailure(ex);
	}

	/**
	 * Refresh the stub and retry the remote invocation if necessary.
	 * <p>If not configured to refresh on connect failure, this method
	 * simply rethrows the original exception.
	 * @param invocation the invocation that failed
	 * @param ex the exception raised on remote invocation
	 * @return the result value of the new invocation, if succeeded
	 * @throws Throwable an exception raised by the new invocation, if failed too.
	 */
	private Object handleRemoteConnectFailure(MethodInvocation invocation, Exception ex) throws Throwable {
		if (this.refreshStubOnConnectFailure) {
			if (logger.isDebugEnabled()) {
				logger.debug("Could not connect to RMI service [" + getJndiName() + "] - retrying", ex);
			}
			else if (logger.isWarnEnabled()) {
				logger.warn("Could not connect to RMI service [" + getJndiName() + "] - retrying");
			}
			return refreshAndRetry(invocation);
		}
		else {
			throw ex;
		}
	}

	/**
	 * Refresh the RMI stub and retry the given invocation.
	 * Called by invoke on connect failure.
	 * @param invocation the AOP method invocation
	 * @return the invocation result, if any
	 * @throws Throwable in case of invocation failure
	 * @see #invoke
	 */
	protected Object refreshAndRetry(MethodInvocation invocation) throws Throwable {
		Remote freshStub = null;
		synchronized (this) {
			try {
				freshStub = lookupStub();
				if (this.cacheStub) {
					this.cachedStub = freshStub;
				}
			}
			catch (Throwable ex) {
				throw new RemoteLookupFailureException("JNDI lookup for RMI service [" + getJndiName() + "] failed", ex);
			}
		}
		return doInvoke(invocation, freshStub);
	}

	/**
	 * Perform the given invocation on the given RMI stub.
	 * @param invocation the AOP method invocation
	 * @param stub the RMI stub to invoke
	 * @return the invocation result, if any
	 * @throws Throwable in case of invocation failure
	 */
	protected Object doInvoke(MethodInvocation invocation, Remote stub) throws Throwable {
		if (stub instanceof RmiInvocationHandler) {
			// RMI invoker
			try {
				return doInvoke(invocation, (RmiInvocationHandler) stub);
			}
			catch (RemoteException ex) {
				throw RmiClientInterceptorUtils.convertRmiAccessException(
				    invocation.getMethod(), ex, isConnectFailure(ex), getJndiName());
			}
			catch (InvocationTargetException ex) {
				throw ex.getTargetException();
			}
			catch (Throwable ex) {
				throw new RemoteProxyFailureException(
						"Failed to invoke RMI stub for remote service [" + getJndiName() + "]", ex);
			}
		}
		else {
			// traditional RMI stub
			try {
				return RmiClientInterceptorUtils.doInvoke(invocation, stub);
			}
			catch (InvocationTargetException ex) {
				Throwable targetEx = ex.getTargetException();
				if (targetEx instanceof RemoteException) {
					RemoteException rex = (RemoteException) targetEx;
					throw RmiClientInterceptorUtils.convertRmiAccessException(
							invocation.getMethod(), rex, isConnectFailure(rex), getJndiName());
				}
				else {
					throw targetEx;
				}
			}
		}
	}

	/**
	 * Apply the given AOP method invocation to the given {@link RmiInvocationHandler}.
	 * <p>The default implementation delegates to {@link #createRemoteInvocation}.
	 * @param methodInvocation the current AOP method invocation
	 * @param invocationHandler the RmiInvocationHandler to apply the invocation to
	 * @return the invocation result
	 * @throws RemoteException in case of communication errors
	 * @throws NoSuchMethodException if the method name could not be resolved
	 * @throws IllegalAccessException if the method could not be accessed
	 * @throws InvocationTargetException if the method invocation resulted in an exception
	 * @see org.springframework.remoting.support.RemoteInvocation
	 */
	protected Object doInvoke(MethodInvocation methodInvocation, RmiInvocationHandler invocationHandler)
	    throws RemoteException, NoSuchMethodException, IllegalAccessException, InvocationTargetException {

		if (AopUtils.isToStringMethod(methodInvocation.getMethod())) {
			return "RMI invoker proxy for service URL [" + getJndiName() + "]";
		}

		return invocationHandler.invoke(createRemoteInvocation(methodInvocation));
	}

	/**
	 * Create a new RemoteInvocation object for the given AOP method invocation.
	 * <p>The default implementation delegates to the configured
	 * {@link #setRemoteInvocationFactory RemoteInvocationFactory}.
	 * This can be overridden in subclasses in order to provide custom RemoteInvocation
	 * subclasses, containing additional invocation parameters (e.g. user credentials).
	 * <p>Note that it is preferable to build a custom RemoteInvocationFactory
	 * as a reusable strategy, instead of overriding this method.
	 * @param methodInvocation the current AOP method invocation
	 * @return the RemoteInvocation object
	 * @see RemoteInvocationFactory#createRemoteInvocation
	 */
	protected RemoteInvocation createRemoteInvocation(MethodInvocation methodInvocation) {
		return getRemoteInvocationFactory().createRemoteInvocation(methodInvocation);
	}

}