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add support interfaces and unit test by way of example for supporting…
… the serialization proxy pattern when the default Serializable implementations fall short

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/proxy/trunk@1581040 13f79535-47bb-0310-9956-ffa450edef68
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mbenson committed Mar 24, 2014
1 parent b43f337 commit 4d8ae971ee71cb9b428be435fd5dbaf16c968be7
Showing 5 changed files with 217 additions and 0 deletions.
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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.commons.proxy2.serialization;

import java.io.Serializable;

/**
* Defines a contract around the {@code Object readResolve()} method used by Java deserialization.
*
* @since 2.0
*/
public interface ReadResolve extends Serializable {
/**
* Get the deserialized version of this {@link Serializable}.
* @return Object
*/
Object readResolve();
}
@@ -0,0 +1,32 @@
/*
* 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.commons.proxy2.serialization;

import java.io.Serializable;

/**
* Defines a contract around the {@code Object writeReplace()} method used by Java deserialization.
*
* @since 2.0
*/
public interface WriteReplace extends Serializable {
/**
* Get the serialized version of this object.
* @return Object
*/
Object writeReplace();
}
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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.
*/
/**
* The various {@link org.apache.commons.proxy2.ProxyFactory} implementations create {@link Serializable} proxies;
* however it is not always possible or practical to serialize the complete structure of a given proxy object. The
* intent of this package is to facilitate the "serialization proxy pattern" by means of the {@code readResolve()} and
* {@code writeReplace} methods supported by Java's serialization mechanism. This would normally be problematic with
* Commons Proxy because its proxies are generalized to expose only methods declared by superclasses (where applicable)
* or proxied interfaces. Therefore we declare the following interfaces:
* <ul>
* <li>{@link ReadResolve}</li>
* <li>{@link WriteReplace}</li>
* </ul>
*
* Typically, you should define your proxy to include {@link WriteReplace} among its interfaces, and implement it to
* return some object that implements {@link ReadResolve} (or simply declares the {@code Object readResolve()} method
* in any scope, but using the interface brings compiler assistance).
*
* Hint: Your {@link ReadResolve#readResolve()} implementation will typically use serialized information to recreate an
* equivalent proxy object, which probably implies some form of {@code static} access.
*/
package org.apache.commons.proxy2.serialization;
import java.io.Serializable;
@@ -55,5 +55,10 @@
<artifactId>commons-proxy2-asm4</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.commons</groupId>
<artifactId>commons-lang3</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
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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.commons.proxy2.serialization;

import static org.junit.Assert.*;

import java.io.Serializable;

import org.apache.commons.lang3.SerializationException;
import org.apache.commons.lang3.SerializationUtils;
import org.apache.commons.proxy2.ProxyFactory;
import org.apache.commons.proxy2.interceptor.InterceptorUtils;
import org.apache.commons.proxy2.interceptor.SwitchInterceptor;
import org.apache.commons.proxy2.interceptor.matcher.invocation.DeclaredByMatcher;
import org.apache.commons.proxy2.stub.AbstractProxyFactoryAgnosticTest;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class SerializationProxyTest extends AbstractProxyFactoryAgnosticTest
{
public static class NonSerializableStringWrapper
{
private final String value;

NonSerializableStringWrapper(String value)
{
this.value = value;
}

public String getValue()
{
return value;
}
}

public interface Provider
{
NonSerializableStringWrapper getObject();
}

private static final ThreadLocal<ProxyFactory> PROXY_FACTORY = new ThreadLocal<ProxyFactory>();

private static SwitchInterceptor implementProvider(String value)
{
return new SwitchInterceptor().when(new DeclaredByMatcher(Provider.class)).then(
InterceptorUtils.constant(new NonSerializableStringWrapper(value)));
}

private static Provider serializableProvider(final String value)
{
return PROXY_FACTORY.get().createInterceptorProxy(
null,
implementProvider(value).when(new DeclaredByMatcher(WriteReplace.class)).then(
InterceptorUtils.constant(new ReadResolve()
{
private static final long serialVersionUID = 1L;

@Override
public Object readResolve()
{
return serializableProvider(value);
}
})), Provider.class, WriteReplace.class);
}

@Before
public void captureProxyFactory()
{
PROXY_FACTORY.set(proxyFactory);
}

@After
public void clearProxyFactory()
{
PROXY_FACTORY.remove();
}

@Test(expected = SerializationException.class)
public void testNaive()
{
final Provider proxy =
proxyFactory.createInterceptorProxy(null, implementProvider("foo"), Provider.class, Serializable.class);
assertEquals("foo", proxy.getObject().getValue());
assertTrue(Serializable.class.isInstance(proxy));
SerializationUtils.roundtrip((Serializable) proxy);
}

@Test
public void testSerializationProxy() {
final Provider proxy = serializableProvider("foo");
assertEquals("foo", proxy.getObject().getValue());
assertTrue(Serializable.class.isInstance(proxy));
final Provider proxy2 = (Provider) SerializationUtils.roundtrip((Serializable) proxy);
assertEquals("foo", proxy2.getObject().getValue());
}
}

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