org.apache.tika.fork.ForkObjectInputStream Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.tika.fork;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamClass;
/**
* An object input stream that uses a given class loader when deserializing
* objects.
*
* Note that this functionality could easily be implemented as a simple
* anonymous {@link ObjectInputStream} subclass, but since the
* functionality is needed during the somewhat complicated bootstrapping
* of the stdin/out communication channel of a forked server process,
* it's better if class has a stable name that can be referenced at
* compile-time by the {@link ForkClient} class.
*/
class ForkObjectInputStream extends ObjectInputStream {
/** The class loader used when deserializing objects. */
private final ClassLoader loader;
/**
* Creates a new object input stream that uses the given class loader
* when deserializing objects.
*
* @param input underlying input stream
* @param loader class loader used when deserializing objects
* @throws IOException if this stream could not be initiated
*/
public ForkObjectInputStream(InputStream input, ClassLoader loader)
throws IOException {
super(input);
this.loader = loader;
}
/**
* Loads the identified class from the specified class loader.
*
* @param desc class description
* @return class loaded class
* @throws ClassNotFoundException if the class can not be found
*/
@Override
protected Class resolveClass(ObjectStreamClass desc)
throws ClassNotFoundException {
return Class.forName(desc.getName(), false, loader);
}
/**
* Serializes the object first into an in-memory buffer and then
* writes it to the output stream with a preceding size integer.
*
* @param object object to be serialized
* @param output output stream
* @throws IOException if the object could not be serialized
*/
public static void sendObject(Object object, DataOutputStream output)
throws IOException {
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
ObjectOutputStream serializer = new ObjectOutputStream(buffer);
serializer.writeObject(object);
serializer.close();
byte[] data = buffer.toByteArray();
output.writeInt(data.length);
output.write(data);
}
/**
* Deserializes an object from the given stream. The serialized object
* is expected to be preceded by a size integer, that is used for reading
* the entire serialization into a memory before deserializing it.
*
* @param input input stream from which the serialized object is read
* @param loader class loader to be used for loading referenced classes
* @throws IOException if the object could not be deserialized
* @throws ClassNotFoundException if a referenced class is not found
*/
public static Object readObject(DataInputStream input, ClassLoader loader)
throws IOException, ClassNotFoundException {
int n = input.readInt();
byte[] data = new byte[n];
input.readFully(data);
ObjectInputStream deserializer =
new ForkObjectInputStream(new ByteArrayInputStream(data), loader);
return deserializer.readObject();
}
}