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/**
*
* Copyright 2005 The Apache Software Foundation or its licensors, as applicable.
*
* 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.apache.tuscany.core.wire.jdk;
import org.apache.tuscany.core.context.TargetException;
import org.apache.tuscany.core.wire.Interceptor;
import org.apache.tuscany.core.wire.InvocationConfiguration;
import org.apache.tuscany.core.wire.TargetInvoker;
import org.apache.tuscany.core.message.Message;
import org.apache.tuscany.core.message.MessageFactory;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
/**
* Receives a request from a JDK proxy and dispatches it to a target invoker or source interceptor stack
*
* @version $Rev$ $Date$
*/
public class JDKInvocationHandler implements InvocationHandler {
private MessageFactory messageFactory;
/*
* an association of an operation to configuration holder. The holder contains the master wire configuration
* and a locale clone of the master TargetInvoker. TargetInvokers will be cloned by the handler and placed in the
* holder if they are cacheable. This allows optimizations such as avoiding target resolution when a source refers
* to a target of greater scope since the target reference can be maintained by the invoker. When a target invoker
* is not cacheable, the master associated with the wire configuration will be used.
*/
private Map<Method, ConfigHolder> configuration;
public JDKInvocationHandler(MessageFactory messageFactory, Map<Method, ? extends InvocationConfiguration> configuration) {
assert (messageFactory != null) : "Message factory was null";
assert (configuration != null) : "Configuration not specified";
this.configuration = new HashMap<Method, ConfigHolder>(configuration.size());
for (Map.Entry<Method, ? extends InvocationConfiguration> entry : configuration.entrySet()) {
this.configuration.put(entry.getKey(), new ConfigHolder(entry.getValue()));
}
this.messageFactory = messageFactory;
}
/**
* Dispatches a client request made on a proxy
*/
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Interceptor headInterceptor = null;
ConfigHolder holder = configuration.get(method);
if (holder == null) {
TargetException e = new TargetException("Operation not configured");
e.setIdentifier(method.getName());
throw e;
}
InvocationConfiguration config = holder.config;
if (config != null) {
headInterceptor = config.getHeadInterceptor();
}
TargetInvoker invoker;
if (holder.cachedInvoker == null) {
assert config != null;
if(config.getTargetInvoker() == null){
TargetException e= new TargetException("No target invoker configured for operation");
e.setIdentifier(config.getMethod().getName());
throw e;
}
if (config.getTargetInvoker().isCacheable()) {
// clone and store the invoker locally
holder.cachedInvoker = (TargetInvoker) config.getTargetInvoker().clone();
invoker = holder.cachedInvoker;
} else {
invoker = config.getTargetInvoker();
}
} else {
assert config != null;
invoker = config.getTargetInvoker();
}
if (headInterceptor == null) {
try {
// short-circuit the dispatch and invoke the target directly
if (config.getTargetInvoker() == null) {
throw new AssertionError("No target invoker [" + method.getName() + "]");
}
return config.getTargetInvoker().invokeTarget(args);
} catch (InvocationTargetException e) {
// the cause was thrown by the target so throw it
throw e.getCause();
}
} else {
Message msg = messageFactory.createMessage();
msg.setTargetInvoker(invoker);
msg.setBody(args);
// dispatch the wire down the chain and get the response
Message resp = headInterceptor.invoke(msg);
Object body = resp.getBody();
if (body instanceof Throwable) {
throw (Throwable) body;
}
return body;
}
}
/**
* A holder used to associate an wire configuration with a local copy of a target invoker that was previously
* cloned from the configuration master
*/
private class ConfigHolder {
public ConfigHolder(InvocationConfiguration config) {
this.config = config;
}
InvocationConfiguration config;
TargetInvoker cachedInvoker;
}
}
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