/*
* Copyright 2002-2011 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.support;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.aop.framework.adapter.AdvisorAdapterRegistry;
import org.springframework.aop.framework.adapter.GlobalAdvisorAdapterRegistry;
import org.springframework.util.ClassUtils;
/**
* Abstract base class for classes that export a remote service.
* Provides "service" and "serviceInterface" bean properties.
*
* <p>Note that the service interface being used will show some signs of
* remotability, like the granularity of method calls that it offers.
* Furthermore, it has to have serializable arguments etc.
*
* @author Juergen Hoeller
* @since 26.12.2003
*/
public abstract class RemoteExporter extends RemotingSupport {
private Object service;
private Class serviceInterface;
private Boolean registerTraceInterceptor;
private Object[] interceptors;
/**
* Set the service to export.
* Typically populated via a bean reference.
*/
public void setService(Object service) {
this.service = service;
}
/**
* Return the service to export.
*/
public Object getService() {
return this.service;
}
/**
* Set the interface of the service to export.
* The interface must be suitable for the particular service and remoting strategy.
*/
public void setServiceInterface(Class serviceInterface) {
if (serviceInterface != null && !serviceInterface.isInterface()) {
throw new IllegalArgumentException("'serviceInterface' must be an interface");
}
this.serviceInterface = serviceInterface;
}
/**
* Return the interface of the service to export.
*/
public Class getServiceInterface() {
return this.serviceInterface;
}
/**
* Set whether to register a RemoteInvocationTraceInterceptor for exported
* services. Only applied when a subclass uses <code>getProxyForService</code>
* for creating the proxy to expose.
* <p>Default is "true". RemoteInvocationTraceInterceptor's most important value
* is that it logs exception stacktraces on the server, before propagating an
* exception to the client. Note that RemoteInvocationTraceInterceptor will <i>not</i>
* be registered by default if the "interceptors" property has been specified.
* @see #setInterceptors
* @see #getProxyForService
* @see RemoteInvocationTraceInterceptor
*/
public void setRegisterTraceInterceptor(boolean registerTraceInterceptor) {
this.registerTraceInterceptor = Boolean.valueOf(registerTraceInterceptor);
}
/**
* Set additional interceptors (or advisors) to be applied before the
* remote endpoint, e.g. a PerformanceMonitorInterceptor.
* <p>You may specify any AOP Alliance MethodInterceptors or other
* Spring AOP Advices, as well as Spring AOP Advisors.
* @see #getProxyForService
* @see org.springframework.aop.interceptor.PerformanceMonitorInterceptor
*/
public void setInterceptors(Object[] interceptors) {
this.interceptors = interceptors;
}
/**
* Check whether the service reference has been set.
* @see #setService
*/
protected void checkService() throws IllegalArgumentException {
if (getService() == null) {
throw new IllegalArgumentException("Property 'service' is required");
}
}
/**
* Check whether a service reference has been set,
* and whether it matches the specified service.
* @see #setServiceInterface
* @see #setService
*/
protected void checkServiceInterface() throws IllegalArgumentException {
Class serviceInterface = getServiceInterface();
Object service = getService();
if (serviceInterface == null) {
throw new IllegalArgumentException("Property 'serviceInterface' is required");
}
if (service instanceof String) {
throw new IllegalArgumentException("Service [" + service + "] is a String " +
"rather than an actual service reference: Have you accidentally specified " +
"the service bean name as value instead of as reference?");
}
if (!serviceInterface.isInstance(service)) {
throw new IllegalArgumentException("Service interface [" + serviceInterface.getName() +
"] needs to be implemented by service [" + service + "] of class [" +
service.getClass().getName() + "]");
}
}
/**
* Get a proxy for the given service object, implementing the specified
* service interface.
* <p>Used to export a proxy that does not expose any internals but just
* a specific interface intended for remote access. Furthermore, a
* {@link RemoteInvocationTraceInterceptor} will be registered (by default).
* @return the proxy
* @see #setServiceInterface
* @see #setRegisterTraceInterceptor
* @see RemoteInvocationTraceInterceptor
*/
protected Object getProxyForService() {
checkService();
checkServiceInterface();
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.addInterface(getServiceInterface());
if (this.registerTraceInterceptor != null ?
this.registerTraceInterceptor.booleanValue() : this.interceptors == null) {
proxyFactory.addAdvice(new RemoteInvocationTraceInterceptor(getExporterName()));
}
if (this.interceptors != null) {
AdvisorAdapterRegistry adapterRegistry = GlobalAdvisorAdapterRegistry.getInstance();
for (int i = 0; i < this.interceptors.length; i++) {
proxyFactory.addAdvisor(adapterRegistry.wrap(this.interceptors[i]));
}
}
proxyFactory.setTarget(getService());
proxyFactory.setOpaque(true);
return proxyFactory.getProxy(getBeanClassLoader());
}
/**
* Return a short name for this exporter.
* Used for tracing of remote invocations.
* <p>Default is the unqualified class name (without package).
* Can be overridden in subclasses.
* @see #getProxyForService
* @see RemoteInvocationTraceInterceptor
* @see org.springframework.util.ClassUtils#getShortName
*/
protected String getExporterName() {
return ClassUtils.getShortName(getClass());
}
}