/*
* 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.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.zip.GZIPInputStream;
import org.springframework.context.i18n.LocaleContext;
import org.springframework.context.i18n.LocaleContextHolder;
import org.springframework.remoting.support.RemoteInvocationResult;
import org.springframework.util.StringUtils;
/**
* HttpInvokerRequestExecutor implementation that uses standard J2SE facilities
* to execute POST requests, without support for HTTP authentication or
* advanced configuration options.
*
* <p>Designed for easy subclassing, customizing specific template methods.
* However, consider CommonsHttpInvokerRequestExecutor for more sophisticated
* needs: The J2SE HttpURLConnection is rather limited in its capabilities.
*
* @author Juergen Hoeller
* @since 1.1
* @see CommonsHttpInvokerRequestExecutor
* @see java.net.HttpURLConnection
*/
public class SimpleHttpInvokerRequestExecutor extends AbstractHttpInvokerRequestExecutor {
/**
* Execute the given request through a standard J2SE HttpURLConnection.
* <p>This method implements the basic processing workflow:
* The actual work happens in this class's template methods.
* @see #openConnection
* @see #prepareConnection
* @see #writeRequestBody
* @see #validateResponse
* @see #readResponseBody
*/
@Override
protected RemoteInvocationResult doExecuteRequest(
HttpInvokerClientConfiguration config, ByteArrayOutputStream baos)
throws IOException, ClassNotFoundException {
HttpURLConnection con = openConnection(config);
prepareConnection(con, baos.size());
writeRequestBody(config, con, baos);
validateResponse(config, con);
InputStream responseBody = readResponseBody(config, con);
return readRemoteInvocationResult(responseBody, config.getCodebaseUrl());
}
/**
* Open an HttpURLConnection for the given remote invocation request.
* @param config the HTTP invoker configuration that specifies the
* target service
* @return the HttpURLConnection for the given request
* @throws IOException if thrown by I/O methods
* @see java.net.URL#openConnection()
*/
protected HttpURLConnection openConnection(HttpInvokerClientConfiguration config) throws IOException {
URLConnection con = new URL(config.getServiceUrl()).openConnection();
if (!(con instanceof HttpURLConnection)) {
throw new IOException("Service URL [" + config.getServiceUrl() + "] is not an HTTP URL");
}
return (HttpURLConnection) con;
}
/**
* Prepare the given HTTP connection.
* <p>The default implementation specifies POST as method,
* "application/x-java-serialized-object" as "Content-Type" header,
* and the given content length as "Content-Length" header.
* @param con the HTTP connection to prepare
* @param contentLength the length of the content to send
* @throws IOException if thrown by HttpURLConnection methods
* @see java.net.HttpURLConnection#setRequestMethod
* @see java.net.HttpURLConnection#setRequestProperty
*/
protected void prepareConnection(HttpURLConnection con, int contentLength) throws IOException {
con.setDoOutput(true);
con.setRequestMethod(HTTP_METHOD_POST);
con.setRequestProperty(HTTP_HEADER_CONTENT_TYPE, getContentType());
con.setRequestProperty(HTTP_HEADER_CONTENT_LENGTH, Integer.toString(contentLength));
LocaleContext locale = LocaleContextHolder.getLocaleContext();
if (locale != null) {
con.setRequestProperty(HTTP_HEADER_ACCEPT_LANGUAGE, StringUtils.toLanguageTag(locale.getLocale()));
}
if (isAcceptGzipEncoding()) {
con.setRequestProperty(HTTP_HEADER_ACCEPT_ENCODING, ENCODING_GZIP);
}
}
/**
* Set the given serialized remote invocation as request body.
* <p>The default implementation simply write the serialized invocation to the
* HttpURLConnection's OutputStream. This can be overridden, for example, to write
* a specific encoding and potentially set appropriate HTTP request headers.
* @param config the HTTP invoker configuration that specifies the target service
* @param con the HttpURLConnection to write the request body to
* @param baos the ByteArrayOutputStream that contains the serialized
* RemoteInvocation object
* @throws IOException if thrown by I/O methods
* @see java.net.HttpURLConnection#getOutputStream()
* @see java.net.HttpURLConnection#setRequestProperty
*/
protected void writeRequestBody(
HttpInvokerClientConfiguration config, HttpURLConnection con, ByteArrayOutputStream baos)
throws IOException {
baos.writeTo(con.getOutputStream());
}
/**
* Validate the given response as contained in the HttpURLConnection object,
* throwing an exception if it does not correspond to a successful HTTP response.
* <p>Default implementation rejects any HTTP status code beyond 2xx, to avoid
* parsing the response body and trying to deserialize from a corrupted stream.
* @param config the HTTP invoker configuration that specifies the target service
* @param con the HttpURLConnection to validate
* @throws IOException if validation failed
* @see java.net.HttpURLConnection#getResponseCode()
*/
protected void validateResponse(HttpInvokerClientConfiguration config, HttpURLConnection con)
throws IOException {
if (con.getResponseCode() >= 300) {
throw new IOException(
"Did not receive successful HTTP response: status code = " + con.getResponseCode() +
", status message = [" + con.getResponseMessage() + "]");
}
}
/**
* Extract the response body from the given executed remote invocation
* request.
* <p>The default implementation simply reads the serialized invocation
* from the HttpURLConnection's InputStream. If the response is recognized
* as GZIP response, the InputStream will get wrapped in a GZIPInputStream.
* @param config the HTTP invoker configuration that specifies the target service
* @param con the HttpURLConnection to read the response body from
* @return an InputStream for the response body
* @throws IOException if thrown by I/O methods
* @see #isGzipResponse
* @see java.util.zip.GZIPInputStream
* @see java.net.HttpURLConnection#getInputStream()
* @see java.net.HttpURLConnection#getHeaderField(int)
* @see java.net.HttpURLConnection#getHeaderFieldKey(int)
*/
protected InputStream readResponseBody(HttpInvokerClientConfiguration config, HttpURLConnection con)
throws IOException {
if (isGzipResponse(con)) {
// GZIP response found - need to unzip.
return new GZIPInputStream(con.getInputStream());
}
else {
// Plain response found.
return con.getInputStream();
}
}
/**
* Determine whether the given response is a GZIP response.
* <p>Default implementation checks whether the HTTP "Content-Encoding"
* header contains "gzip" (in any casing).
* @param con the HttpURLConnection to check
*/
protected boolean isGzipResponse(HttpURLConnection con) {
String encodingHeader = con.getHeaderField(HTTP_HEADER_CONTENT_ENCODING);
return (encodingHeader != null && encodingHeader.toLowerCase().indexOf(ENCODING_GZIP) != -1);
}
}
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