/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.remoting.rmi;

import java.io.IOException;
import java.io.InputStream;
import java.rmi.server.RMIClassLoader;

import org.springframework.core.ConfigurableObjectInputStream;
import org.springframework.lang.Nullable;

Special ObjectInputStream subclass that falls back to a specified codebase
to load classes from if not found locally. In contrast to standard RMI
conventions for dynamic class download, it is the client that determines
the codebase URL here, rather than the "java.rmi.server.codebase" system
property on the server.
Uses the JDK's RMIClassLoader to load classes from the specified codebase.
The codebase can consist of multiple URLs, separated by spaces.
Note that RMIClassLoader requires a SecurityManager to be set, like when
using dynamic class download with standard RMI! (See the RMI documentation
for details.)
Despite residing in the RMI package, this class is not used for
RmiClientInterceptor, which uses the standard RMI infrastructure instead
and thus is only able to rely on RMI's standard dynamic class download via
"java.rmi.server.codebase". CodebaseAwareObjectInputStream is used by
HttpInvokerClientInterceptor (see the "codebaseUrl" property there).
Thanks to Lionel Mestre for suggesting the option and providing
a prototype!
Author:
Juergen Hoeller
See Also:
RMIClassLoader
RemoteInvocationSerializingExporter.createObjectInputStream
setCodebaseUrl.setCodebaseUrl
Since:
1.1.3/**
 * Special ObjectInputStream subclass that falls back to a specified codebase
 * to load classes from if not found locally. In contrast to standard RMI
 * conventions for dynamic class download, it is the client that determines
 * the codebase URL here, rather than the "java.rmi.server.codebase" system
 * property on the server.
 *
 * <p>Uses the JDK's RMIClassLoader to load classes from the specified codebase.
 * The codebase can consist of multiple URLs, separated by spaces.
 * Note that RMIClassLoader requires a SecurityManager to be set, like when
 * using dynamic class download with standard RMI! (See the RMI documentation
 * for details.)
 *
 * <p>Despite residing in the RMI package, this class is <i>not</i> used for
 * RmiClientInterceptor, which uses the standard RMI infrastructure instead
 * and thus is only able to rely on RMI's standard dynamic class download via
 * "java.rmi.server.codebase". CodebaseAwareObjectInputStream is used by
 * HttpInvokerClientInterceptor (see the "codebaseUrl" property there).
 *
 * <p>Thanks to Lionel Mestre for suggesting the option and providing
 * a prototype!
 *
 * @author Juergen Hoeller
 * @since 1.1.3
 * @see java.rmi.server.RMIClassLoader
 * @see RemoteInvocationSerializingExporter#createObjectInputStream
 * @see org.springframework.remoting.httpinvoker.HttpInvokerClientInterceptor#setCodebaseUrl
 */
public class CodebaseAwareObjectInputStream extends ConfigurableObjectInputStream {

	private final String codebaseUrl;


	
Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
Params:
in – the InputStream to read from
codebaseUrl – the codebase URL to load classes from if not found locally
(can consist of multiple URLs, separated by spaces)
See Also:
ObjectInputStream(InputStream)/**
	 * Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
	 * @param in the InputStream to read from
	 * @param codebaseUrl the codebase URL to load classes from if not found locally
	 * (can consist of multiple URLs, separated by spaces)
	 * @see java.io.ObjectInputStream#ObjectInputStream(java.io.InputStream)
	 */
	public CodebaseAwareObjectInputStream(InputStream in, String codebaseUrl) throws IOException {
		this(in, null, codebaseUrl);
	}

	
Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
Params:
in – the InputStream to read from
classLoader – the ClassLoader to use for loading local classes (may be null to indicate RMI's default ClassLoader)
codebaseUrl – the codebase URL to load classes from if not found locally
(can consist of multiple URLs, separated by spaces)
See Also:
ObjectInputStream(InputStream)/**
	 * Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
	 * @param in the InputStream to read from
	 * @param classLoader the ClassLoader to use for loading local classes
	 * (may be {@code null} to indicate RMI's default ClassLoader)
	 * @param codebaseUrl the codebase URL to load classes from if not found locally
	 * (can consist of multiple URLs, separated by spaces)
	 * @see java.io.ObjectInputStream#ObjectInputStream(java.io.InputStream)
	 */
	public CodebaseAwareObjectInputStream(
			InputStream in, @Nullable ClassLoader classLoader, String codebaseUrl) throws IOException {

		super(in, classLoader);
		this.codebaseUrl = codebaseUrl;
	}

	
Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
Params:
in – the InputStream to read from
classLoader – the ClassLoader to use for loading local classes (may be null to indicate RMI's default ClassLoader)
acceptProxyClasses – whether to accept deserialization of proxy classes
(may be deactivated as a security measure)
See Also:
ObjectInputStream(InputStream)/**
	 * Create a new CodebaseAwareObjectInputStream for the given InputStream and codebase.
	 * @param in the InputStream to read from
	 * @param classLoader the ClassLoader to use for loading local classes
	 * (may be {@code null} to indicate RMI's default ClassLoader)
	 * @param acceptProxyClasses whether to accept deserialization of proxy classes
	 * (may be deactivated as a security measure)
	 * @see java.io.ObjectInputStream#ObjectInputStream(java.io.InputStream)
	 */
	public CodebaseAwareObjectInputStream(
			InputStream in, @Nullable ClassLoader classLoader, boolean acceptProxyClasses) throws IOException {

		super(in, classLoader, acceptProxyClasses);
		this.codebaseUrl = null;
	}


	@Override
	protected Class<?> resolveFallbackIfPossible(String className, ClassNotFoundException ex)
			throws IOException, ClassNotFoundException {

		// If codebaseUrl is set, try to load the class with the RMIClassLoader.
		// Else, propagate the ClassNotFoundException.
		if (this.codebaseUrl == null) {
			throw ex;
		}
		return RMIClassLoader.loadClass(this.codebaseUrl, className);
	}

	@Override
	protected ClassLoader getFallbackClassLoader() throws IOException {
		return RMIClassLoader.getClassLoader(this.codebaseUrl);
	}

}