Spring Framework example source code file (CodebaseAwareObjectInputStream.java)

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Java - Spring Framework tags/keywords

class, class, classloader, classnotfoundexception, classnotfoundexception, codebaseawareobjectinputstream, codebaseawareobjectinputstream, illegalargumentexception, inputstream, io, ioexception, ioexception, objectinputstream, reflection, string

The Spring Framework CodebaseAwareObjectInputStream.java source code

/*
 * Copyright 2002-2008 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.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.lang.reflect.Proxy;
import java.rmi.server.RMIClassLoader;

import org.springframework.util.ClassUtils;

/**
 * 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 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).
 *
 * <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 ObjectInputStream {

	private final ClassLoader classLoader;

	private final String codebaseUrl;


	/**
	 * 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.
	 * @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, ClassLoader classLoader, String codebaseUrl) throws IOException {

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


	/**
	 * Overridden version delegates to super class first,
	 * falling back to the specified codebase if not found locally.
	 */
	protected Class resolveClass(ObjectStreamClass classDesc) throws IOException, ClassNotFoundException {
		try {
			if (this.classLoader != null) {
				// Use the specified ClassLoader to resolve local classes.
				return ClassUtils.forName(classDesc.getName(), this.classLoader);
			}
			else {
				// Let RMI use it's default ClassLoader...
				return super.resolveClass(classDesc);
			}
		}
		catch (ClassNotFoundException ex) {
			// 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, classDesc.getName());
		}
	}

	/**
	 * Overridden version delegates to super class first,
	 * falling back to the specified codebase if not found locally.
	 */
	protected Class resolveProxyClass(String[] interfaces) throws IOException, ClassNotFoundException {
		if (this.classLoader != null) {
			// Use the specified ClassLoader to resolve local proxy classes.
			Class[] resolvedInterfaces = new Class[interfaces.length];
			for (int i = 0; i < interfaces.length; i++) {
				try {
					resolvedInterfaces[i] = ClassUtils.forName(interfaces[i], this.classLoader);
				}
				catch (ClassNotFoundException ex) {
					if (this.codebaseUrl == null) {
						throw ex;
					}
					resolvedInterfaces[i] = RMIClassLoader.loadClass(this.codebaseUrl, interfaces[i]);
				}
			}
			try {
				return Proxy.getProxyClass(this.classLoader, resolvedInterfaces);
			}
			catch (IllegalArgumentException ex) {
				throw new ClassNotFoundException(null, ex);
			}
		}
		else {
			// Let RMI use it's default ClassLoader...
			try {
				return super.resolveProxyClass(interfaces);
			}
			catch (ClassNotFoundException ex) {
				if (this.codebaseUrl == null) {
					throw ex;
				}
				ClassLoader loader = RMIClassLoader.getClassLoader(this.codebaseUrl);
				Class[] resolvedInterfaces = new Class[interfaces.length];
				for (int i = 0; i < interfaces.length; i++) {
					resolvedInterfaces[i] = loader.loadClass(interfaces[i]);
				}
				return Proxy.getProxyClass(loader, resolvedInterfaces);
			}
		}
	}

}