/*
* 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.rmi.server.RMIClassLoader;
import org.springframework.core.ConfigurableObjectInputStream;
/**
* 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.
* @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</code> 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, classLoader);
this.codebaseUrl = codebaseUrl;
}
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);
}
protected ClassLoader getFallbackClassLoader() throws IOException {
return RMIClassLoader.getClassLoader(this.codebaseUrl);
}
}