Spring Framework example source code file (HttpInvokerClientInterceptor.java)

This example Spring Framework source code file (HttpInvokerClientInterceptor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

could, could, exception, http, http, httpinvokerrequestexecutor, io, net, network, remoteaccessexception, remoteinvocation, remoteinvocationresult, remoteinvocationresult, simplehttpinvokerrequestexecutor, string, throwable, throwable

The Spring Framework HttpInvokerClientInterceptor.java source code

/*
 * Copyright 2002-2008 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.httpinvoker;

import java.io.IOException;
import java.io.InvalidClassException;
import java.net.ConnectException;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.aop.support.AopUtils;
import org.springframework.remoting.RemoteAccessException;
import org.springframework.remoting.RemoteConnectFailureException;
import org.springframework.remoting.RemoteInvocationFailureException;
import org.springframework.remoting.support.RemoteInvocation;
import org.springframework.remoting.support.RemoteInvocationBasedAccessor;
import org.springframework.remoting.support.RemoteInvocationResult;

/**
 * {@link org.aopalliance.intercept.MethodInterceptor} for accessing an
 * HTTP invoker service. The service URL must be an HTTP URL exposing
 * an HTTP invoker service.
 *
 * <p>Serializes remote invocation objects and deserializes remote invocation
 * result objects. Uses Java serialization just like RMI, but provides the
 * same ease of setup as Caucho's HTTP-based Hessian and Burlap protocols.
 *
 * <P>HTTP invoker is a very extensible and customizable protocol.
 * It supports the RemoteInvocationFactory mechanism, like RMI invoker,
 * allowing to include additional invocation attributes (for example,
 * a security context). Furthermore, it allows to customize request
 * execution via the {@link HttpInvokerRequestExecutor} strategy.
 *
 * <p>Can use the JDK's {@link java.rmi.server.RMIClassLoader} to load
 * classes from a given {@link #setCodebaseUrl codebase}, performing
 * on-demand dynamic code download from a remote location. The codebase
 * can consist of multiple URLs, separated by spaces. Note that
 * RMIClassLoader requires a SecurityManager to be set, analogous to
 * when using dynamic class download with standard RMI!
 * (See the RMI documentation for details.)
 *
 * @author Juergen Hoeller
 * @since 1.1
 * @see #setServiceUrl
 * @see #setCodebaseUrl
 * @see #setRemoteInvocationFactory
 * @see #setHttpInvokerRequestExecutor
 * @see HttpInvokerServiceExporter
 * @see HttpInvokerProxyFactoryBean
 * @see java.rmi.server.RMIClassLoader
 */
public class HttpInvokerClientInterceptor extends RemoteInvocationBasedAccessor
		implements MethodInterceptor, HttpInvokerClientConfiguration {

	private String codebaseUrl;

	private HttpInvokerRequestExecutor httpInvokerRequestExecutor;


	/**
	 * Set the codebase URL to download classes from if not found locally.
	 * Can consists of multiple URLs, separated by spaces.
	 * <p>Follows RMI's codebase conventions for dynamic class download.
	 * In contrast to RMI, where the server determines the URL for class download
	 * (via the "java.rmi.server.codebase" system property), it's the client
	 * that determines the codebase URL here. The server will usually be the
	 * same as for the service URL, just pointing to a different path there.
	 * @see #setServiceUrl
	 * @see org.springframework.remoting.rmi.CodebaseAwareObjectInputStream
	 * @see java.rmi.server.RMIClassLoader
	 */
	public void setCodebaseUrl(String codebaseUrl) {
		this.codebaseUrl = codebaseUrl;
	}

	/**
	 * Return the codebase URL to download classes from if not found locally.
	 */
	public String getCodebaseUrl() {
		return this.codebaseUrl;
	}

	/**
	 * Set the HttpInvokerRequestExecutor implementation to use for executing
	 * remote invocations.
	 * <p>Default is {@link SimpleHttpInvokerRequestExecutor}. Alternatively,
	 * consider using {@link CommonsHttpInvokerRequestExecutor} for more
	 * sophisticated needs.
	 * @see SimpleHttpInvokerRequestExecutor
	 * @see CommonsHttpInvokerRequestExecutor
	 */
	public void setHttpInvokerRequestExecutor(HttpInvokerRequestExecutor httpInvokerRequestExecutor) {
		this.httpInvokerRequestExecutor = httpInvokerRequestExecutor;
	}

	/**
	 * Return the HttpInvokerRequestExecutor used by this remote accessor.
	 * <p>Creates a default SimpleHttpInvokerRequestExecutor if no executor
	 * has been initialized already.
	 */
	public HttpInvokerRequestExecutor getHttpInvokerRequestExecutor() {
		if (this.httpInvokerRequestExecutor == null) {
			SimpleHttpInvokerRequestExecutor executor = new SimpleHttpInvokerRequestExecutor();
			executor.setBeanClassLoader(getBeanClassLoader());
			this.httpInvokerRequestExecutor = executor;
		}
		return this.httpInvokerRequestExecutor;
	}

	public void afterPropertiesSet() {
		super.afterPropertiesSet();

		// Eagerly initialize the default HttpInvokerRequestExecutor, if needed.
		getHttpInvokerRequestExecutor();
	}


	public Object invoke(MethodInvocation methodInvocation) throws Throwable {
		if (AopUtils.isToStringMethod(methodInvocation.getMethod())) {
			return "HTTP invoker proxy for service URL [" + getServiceUrl() + "]";
		}

		RemoteInvocation invocation = createRemoteInvocation(methodInvocation);
		RemoteInvocationResult result = null;
		try {
			result = executeRequest(invocation, methodInvocation);
		}
		catch (Throwable ex) {
			throw convertHttpInvokerAccessException(ex);
		}
		try {
			return recreateRemoteInvocationResult(result);
		}
		catch (Throwable ex) {
			if (result.hasInvocationTargetException()) {
				throw ex;
			}
			else {
				throw new RemoteInvocationFailureException("Invocation of method [" + methodInvocation.getMethod() +
						"] failed in HTTP invoker remote service at [" + getServiceUrl() + "]", ex);
			}
		}
	}

	/**
	 * Execute the given remote invocation via the HttpInvokerRequestExecutor.
	 * <p>This implementation delegates to {@link #executeRequest(RemoteInvocation)}.
	 * Can be overridden to react to the specific original MethodInvocation.
	 * @param invocation the RemoteInvocation to execute
	 * @param originalInvocation the original MethodInvocation (can e.g. be cast
	 * to the ProxyMethodInvocation interface for accessing user attributes)
	 * @return the RemoteInvocationResult object
	 * @throws Exception in case of errors
	 */
	protected RemoteInvocationResult executeRequest(
			RemoteInvocation invocation, MethodInvocation originalInvocation) throws Exception {

		return executeRequest(invocation);
	}

	/**
	 * Execute the given remote invocation via the HttpInvokerRequestExecutor.
	 * <p>Can be overridden in subclasses to pass a different configuration object
	 * to the executor. Alternatively, add further configuration properties in a
	 * subclass of this accessor: By default, the accessor passed itself as
	 * configuration object to the executor.
	 * @param invocation the RemoteInvocation to execute
	 * @return the RemoteInvocationResult object
	 * @throws IOException if thrown by I/O operations
	 * @throws ClassNotFoundException if thrown during deserialization
	 * @throws Exception in case of general errors
	 * @see #getHttpInvokerRequestExecutor
	 * @see HttpInvokerClientConfiguration
	 */
	protected RemoteInvocationResult executeRequest(RemoteInvocation invocation) throws Exception {
		return getHttpInvokerRequestExecutor().executeRequest(this, invocation);
	}

	/**
	 * Convert the given HTTP invoker access exception to an appropriate
	 * Spring RemoteAccessException.
	 * @param ex the exception to convert
	 * @return the RemoteAccessException to throw
	 */
	protected RemoteAccessException convertHttpInvokerAccessException(Throwable ex) {
		if (ex instanceof ConnectException) {
			throw new RemoteConnectFailureException(
					"Could not connect to HTTP invoker remote service at [" + getServiceUrl() + "]", ex);
		}
		else if (ex instanceof ClassNotFoundException || ex instanceof NoClassDefFoundError ||
				ex instanceof InvalidClassException) {
			throw new RemoteAccessException(
					"Could not deserialize result from HTTP invoker remote service [" + getServiceUrl() + "]", ex);
		}
		else {
			throw new RemoteAccessException(
			    "Could not access HTTP invoker remote service at [" + getServiceUrl() + "]", ex);
		}
	}

}