/**
* 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.camel.component.bean;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;
import org.apache.camel.Body;
import org.apache.camel.CamelContext;
import org.apache.camel.CamelExchangeException;
import org.apache.camel.Endpoint;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.ExchangeProperty;
import org.apache.camel.Header;
import org.apache.camel.Headers;
import org.apache.camel.InvalidPayloadException;
import org.apache.camel.Producer;
import org.apache.camel.RuntimeCamelException;
import org.apache.camel.impl.DefaultExchange;
import org.apache.camel.util.ObjectHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public abstract class AbstractCamelInvocationHandler implements InvocationHandler {
private static final Logger LOG = LoggerFactory.getLogger(CamelInvocationHandler.class);
private static final List<Method> EXCLUDED_METHODS = new ArrayList<Method>();
private static ExecutorService executorService;
protected final Endpoint endpoint;
protected final Producer producer;
static {
// exclude all java.lang.Object methods as we dont want to invoke them
EXCLUDED_METHODS.addAll(Arrays.asList(Object.class.getMethods()));
}
public AbstractCamelInvocationHandler(Endpoint endpoint, Producer producer) {
this.endpoint = endpoint;
this.producer = producer;
}
private static Object getBody(Exchange exchange, Class<?> type) throws InvalidPayloadException {
// get the body from the Exchange from either OUT or IN
if (exchange.hasOut()) {
if (exchange.getOut().getBody() != null) {
return exchange.getOut().getMandatoryBody(type);
} else {
return null;
}
} else {
if (exchange.getIn().getBody() != null) {
return exchange.getIn().getMandatoryBody(type);
} else {
return null;
}
}
}
@Override
public final Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
if (isValidMethod(method)) {
return doInvokeProxy(proxy, method, args);
} else {
// invalid method then invoke methods on this instead
if ("toString".equals(method.getName())) {
return this.toString();
} else if ("hashCode".equals(method.getName())) {
return this.hashCode();
} else if ("equals".equals(method.getName())) {
return Boolean.FALSE;
}
return null;
}
}
public abstract Object doInvokeProxy(Object proxy, Method method, Object[] args) throws Throwable;
@SuppressWarnings("unchecked")
protected Object invokeProxy(final Method method, final ExchangePattern pattern, Object[] args, boolean binding) throws Throwable {
final Exchange exchange = new DefaultExchange(endpoint, pattern);
//Need to check if there are mutiple arguments and the parameters have no annotations for binding,
//then use the original bean invocation.
boolean canUseBinding = method.getParameterCount() == 1;
if (!canUseBinding) {
for (Parameter parameter : method.getParameters()) {
if (parameter.isAnnotationPresent(Header.class)
|| parameter.isAnnotationPresent(Headers.class)
|| parameter.isAnnotationPresent(ExchangeProperty.class)
|| parameter.isAnnotationPresent(Body.class)) {
canUseBinding = true;
}
}
}
if (binding && canUseBinding) {
// in binding mode we bind the passed in arguments (args) to the created exchange
// using the existing Camel @Body, @Header, @Headers, @ExchangeProperty annotations
// if no annotation then its bound as the message body
int index = 0;
for (Annotation[] row : method.getParameterAnnotations()) {
Object value = args[index];
if (row == null || row.length == 0) {
// assume its message body when there is no annotations
exchange.getIn().setBody(value);
} else {
for (Annotation ann : row) {
if (ann.annotationType().isAssignableFrom(Header.class)) {
Header header = (Header) ann;
String name = header.value();
exchange.getIn().setHeader(name, value);
} else if (ann.annotationType().isAssignableFrom(Headers.class)) {
Map map = exchange.getContext().getTypeConverter().tryConvertTo(Map.class, exchange, value);
if (map != null) {
exchange.getIn().getHeaders().putAll(map);
}
} else if (ann.annotationType().isAssignableFrom(ExchangeProperty.class)) {
ExchangeProperty ep = (ExchangeProperty) ann;
String name = ep.value();
exchange.setProperty(name, value);
} else if (ann.annotationType().isAssignableFrom(Body.class)) {
exchange.getIn().setBody(value);
} else {
// assume its message body when there is no annotations
exchange.getIn().setBody(value);
}
}
}
index++;
}
} else {
// no binding so use the old behavior with BeanInvocation as the body
BeanInvocation invocation = new BeanInvocation(method, args);
exchange.getIn().setBody(invocation);
}
if (binding) {
LOG.trace("Binding to service interface as @Body,@Header,@ExchangeProperty detected when calling proxy method: {}", method);
} else {
LOG.trace("No binding to service interface as @Body,@Header,@ExchangeProperty not detected. Using BeanInvocation as message body when calling proxy method: {}");
}
return doInvoke(method, exchange);
}
protected Object invokeWithBody(final Method method, Object body, final ExchangePattern pattern) throws Throwable {
final Exchange exchange = new DefaultExchange(endpoint, pattern);
exchange.getIn().setBody(body);
return doInvoke(method, exchange);
}
protected Object doInvoke(final Method method, final Exchange exchange) throws Throwable {
// is the return type a future
final boolean isFuture = method.getReturnType() == Future.class;
// create task to execute the proxy and gather the reply
FutureTask<Object> task = new FutureTask<Object>(new Callable<Object>() {
public Object call() throws Exception {
// process the exchange
LOG.trace("Proxied method call {} invoking producer: {}", method.getName(), producer);
producer.process(exchange);
Object answer = afterInvoke(method, exchange, exchange.getPattern(), isFuture);
LOG.trace("Proxied method call {} returning: {}", method.getName(), answer);
return answer;
}
});
if (isFuture) {
// submit task and return future
if (LOG.isTraceEnabled()) {
LOG.trace("Submitting task for exchange id {}", exchange.getExchangeId());
}
getExecutorService(exchange.getContext()).submit(task);
return task;
} else {
// execute task now
try {
task.run();
return task.get();
} catch (ExecutionException e) {
// we don't want the wrapped exception from JDK
throw e.getCause();
}
}
}
protected Object afterInvoke(Method method, Exchange exchange, ExchangePattern pattern, boolean isFuture) throws Exception {
// check if we had an exception
Throwable cause = exchange.getException();
if (cause != null) {
Throwable found = findSuitableException(cause, method);
if (found != null) {
if (found instanceof Exception) {
throw (Exception)found;
} else {
// wrap as exception
throw new CamelExchangeException("Error processing exchange", exchange, cause);
}
}
// special for runtime camel exceptions as they can be nested
if (cause instanceof RuntimeCamelException) {
// if the inner cause is a runtime exception we can throw it
// directly
if (cause.getCause() instanceof RuntimeException) {
throw (RuntimeException)((RuntimeCamelException)cause).getCause();
}
throw (RuntimeCamelException)cause;
}
// okay just throw the exception as is
if (cause instanceof Exception) {
throw (Exception)cause;
} else {
// wrap as exception
throw new CamelExchangeException("Error processing exchange", exchange, cause);
}
}
Class<?> to = isFuture ? getGenericType(exchange.getContext(), method.getGenericReturnType()) : method.getReturnType();
// do not return a reply if the method is VOID
if (to == Void.TYPE) {
return null;
}
return getBody(exchange, to);
}
protected static Class<?> getGenericType(CamelContext context, Type type) throws ClassNotFoundException {
if (type == null) {
// fallback and use object
return Object.class;
}
// unfortunately java dont provide a nice api for getting the generic
// type of the return type
// due type erasure, so we have to gather it based on a String
// representation
String name = ObjectHelper.between(type.toString(), "<", ">");
if (name != null) {
if (name.contains("<")) {
// we only need the outer type
name = ObjectHelper.before(name, "<");
}
return context.getClassResolver().resolveMandatoryClass(name);
} else {
// fallback and use object
return Object.class;
}
}
@SuppressWarnings("deprecation")
protected static synchronized ExecutorService getExecutorService(CamelContext context) {
// CamelContext will shutdown thread pool when it shutdown so we can
// lazy create it on demand
// but in case of hot-deploy or the likes we need to be able to
// re-create it (its a shared static instance)
if (executorService == null || executorService.isTerminated() || executorService.isShutdown()) {
// try to lookup a pool first based on id/profile
executorService = context.getExecutorServiceStrategy().lookup(CamelInvocationHandler.class, "CamelInvocationHandler", "CamelInvocationHandler");
if (executorService == null) {
executorService = context.getExecutorServiceStrategy().newDefaultThreadPool(CamelInvocationHandler.class, "CamelInvocationHandler");
}
}
return executorService;
}
/**
* Tries to find the best suited exception to throw.
* <p/>
* It looks in the exception hierarchy from the caused exception and matches
* this against the declared exceptions being thrown on the method.
*
* @param cause the caused exception
* @param method the method
* @return the exception to throw, or <tt>null</tt> if not possible to find
* a suitable exception
*/
protected Throwable findSuitableException(Throwable cause, Method method) {
if (method.getExceptionTypes() == null || method.getExceptionTypes().length == 0) {
return null;
}
// see if there is any exception which matches the declared exception on
// the method
for (Class<?> type : method.getExceptionTypes()) {
Object fault = ObjectHelper.getException(type, cause);
if (fault != null) {
return Throwable.class.cast(fault);
}
}
return null;
}
protected boolean isValidMethod(Method method) {
// must not be in the excluded list
for (Method excluded : EXCLUDED_METHODS) {
if (ObjectHelper.isOverridingMethod(excluded, method)) {
// the method is overriding an excluded method so its not valid
return false;
}
}
return true;
}
}