/*
* Copyright 2010-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.http;
import com.amazonaws.AmazonWebServiceResponse;
import com.amazonaws.ResponseMetadata;
import com.amazonaws.transform.StaxUnmarshallerContext;
import com.amazonaws.transform.Unmarshaller;
import com.amazonaws.transform.VoidStaxUnmarshaller;
import com.amazonaws.util.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Map;
import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
/**
* Default implementation of HttpResponseHandler that handles a successful
* response from an AWS service and unmarshalls the result using a StAX
* unmarshaller.
*
* @param <T>
* Indicates the type being unmarshalled by this response handler.
*/
public class StaxResponseHandler<T> implements HttpResponseHandler<AmazonWebServiceResponse<T>> {
/** The StAX unmarshaller to use when handling the response */
private Unmarshaller<T, StaxUnmarshallerContext> responseUnmarshaller;
/** Shared logger for profiling information */
private static final Log log = LogFactory.getLog("com.amazonaws.request");
/** Shared factory for creating XML event readers */
private static final XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance();
/**
* Constructs a new response handler that will use the specified StAX
* unmarshaller to unmarshall the service response and uses the specified
* response element path to find the root of the business data in the
* service's response.
*
* @param responseUnmarshaller
* The StAX unmarshaller to use on the response.
*/
public StaxResponseHandler(Unmarshaller<T, StaxUnmarshallerContext> responseUnmarshaller) {
this.responseUnmarshaller = responseUnmarshaller;
/*
* Even if the invoked operation just returns null, we still need an
* unmarshaller to run so we can pull out response metadata.
*
* We might want to pass this in through the client class so that we
* don't have to do this check here.
*/
if (this.responseUnmarshaller == null) {
this.responseUnmarshaller = new VoidStaxUnmarshaller<T>();
}
}
/**
* @see HttpResponseHandler#handle(HttpResponse)
*/
public AmazonWebServiceResponse<T> handle(HttpResponse response) throws Exception {
log.trace("Parsing service response XML");
InputStream content = response.getContent();
if (content == null) {
content = new ByteArrayInputStream("<eof/>".getBytes(StringUtils.UTF8));
}
XMLEventReader eventReader;
synchronized (xmlInputFactory) {
eventReader = xmlInputFactory.createXMLEventReader(content);
}
try {
AmazonWebServiceResponse<T> awsResponse = new AmazonWebServiceResponse<T>();
StaxUnmarshallerContext unmarshallerContext = new StaxUnmarshallerContext(eventReader, response.getHeaders());
unmarshallerContext.registerMetadataExpression("ResponseMetadata/RequestId", 2, ResponseMetadata.AWS_REQUEST_ID);
unmarshallerContext.registerMetadataExpression("requestId", 2, ResponseMetadata.AWS_REQUEST_ID);
registerAdditionalMetadataExpressions(unmarshallerContext);
T result = responseUnmarshaller.unmarshall(unmarshallerContext);
awsResponse.setResult(result);
Map<String, String> metadata = unmarshallerContext.getMetadata();
Map<String, String> responseHeaders = response.getHeaders();
if (responseHeaders != null) {
if (responseHeaders.get(X_AMZN_REQUEST_ID_HEADER) != null) {
metadata.put(ResponseMetadata.AWS_REQUEST_ID,
responseHeaders.get(X_AMZN_REQUEST_ID_HEADER));
}
}
awsResponse.setResponseMetadata(getResponseMetadata(metadata));
log.trace("Done parsing service response");
return awsResponse;
} catch (XMLStreamException e) {
// If the exception was caused by an IOE, wrap this in an IOE so
// that it will be exposed to the RetryPolicy.
if (e.getNestedException() instanceof IOException) {
throw new IOException(e);
}
throw e;
} finally {
try {
eventReader.close();
} catch (XMLStreamException e) {
log.warn("Error closing xml parser", e);
}
}
}
/**
* Create the default {@link ResponseMetadata}. Subclasses may override this to create a
* subclass of {@link ResponseMetadata}. Currently only SimpleDB does this.
*/
protected ResponseMetadata getResponseMetadata(Map<String, String> metadata) {
return new ResponseMetadata(metadata);
}
/**
* Hook for subclasses to override in order to collect additional metadata
* from service responses.
*
* @param unmarshallerContext
* The unmarshaller context used to configure a service's response
* data.
*/
protected void registerAdditionalMetadataExpressions(StaxUnmarshallerContext unmarshallerContext) {}
/**
* Since this response handler completely consumes all the data from the
* underlying HTTP connection during the handle method, we don't need to
* keep the HTTP connection open.
*
* @see com.amazonaws.http.HttpResponseHandler#needsConnectionLeftOpen()
*/
public boolean needsConnectionLeftOpen() {
return false;
}
}