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The AWS SDK for Java - module holds the classes for AWS Xml protocol
/*
* Copyright 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 software.amazon.awssdk.protocols.xml.internal.marshall;
import java.io.IOException;
import java.io.Writer;
import java.nio.ByteBuffer;
import java.util.Date;
import java.util.Map;
import java.util.Stack;
import software.amazon.awssdk.annotations.SdkInternalApi;
import software.amazon.awssdk.core.exception.SdkClientException;
import software.amazon.awssdk.utils.BinaryUtils;
import software.amazon.awssdk.utils.DateUtils;
import software.amazon.awssdk.utils.StringUtils;
/**
* Utility for creating easily creating XML documents, one element at a time.
*/
@SdkInternalApi
class XmlWriter {
static final String[] ESCAPE_SEARCHES = {
// Ampersands should always be the first to escape
"&", "\"", "'", "<", ">", "\r", "\n"
};
static final String[] ESCAPE_REPLACEMENTS = {
"&", """, "'", "<", ">", "
", "
"
};
/** Standard XML prolog to add to the beginning of each XML document. */
private static final String PROLOG = "";
private static final String[] UNESCAPE_SEARCHES = {
// Ampersands should always be the last to unescape
""", "'", "<", ">", "
", "
", "&"
};
private static final String[] UNESCAPE_REPLACEMENTS = {
"\"", "'", "<", ">", "\r", "\n", "&"
};
/** The writer to which the XML document created by this writer will be written. */
private final Writer writer;
/** Optional XML namespace attribute value to include in the root element. */
private final String xmlns;
private Stack elementStack = new Stack<>();
private boolean rootElement = true;
private boolean writtenProlog = false;
/**
* Creates a new XMLWriter, ready to write an XML document to the specified
* writer. The root element in the XML document will specify an xmlns
* attribute with the specified namespace parameter.
*
* @param w
* The writer this XMLWriter will write to.
* @param xmlns
* The XML namespace to include in the xmlns attribute of the
* root element.
*/
XmlWriter(Writer w, String xmlns) {
this.writer = w;
this.xmlns = xmlns;
}
/**
* Starts a new element with the specified name at the current position in
* the in-progress XML document.
*
* @param element
* The name of the new element.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
XmlWriter startElement(String element) {
// Only append the PROLOG if there is XML written.
if (!writtenProlog) {
writtenProlog = true;
append(PROLOG);
}
append("<" + element);
if (rootElement && xmlns != null) {
append(" xmlns=\"" + xmlns + "\"");
rootElement = false;
}
append(">");
elementStack.push(element);
return this;
}
/**
* Start to write an element with xml attributes.
*
* @param element the elment to write
* @param attributes the xml attribtues
* @return the XmlWriter
*/
XmlWriter startElement(String element, Map attributes) {
append("<" + element);
for (Map.Entry attribute: attributes.entrySet()) {
append(" " + attribute.getKey() + "=\"" + attribute.getValue() + "\"");
}
append(">");
elementStack.push(element);
return this;
}
/**
* Closes the last opened element at the current position in the in-progress
* XML document.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
XmlWriter endElement() {
String lastElement = elementStack.pop();
append("");
return this;
}
/**
* Adds the specified value as text to the current position of the in
* progress XML document.
*
* @param s
* The text to add to the XML document.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
public XmlWriter value(String s) {
append(escapeXmlEntities(s));
return this;
}
/**
* Adds the specified value as Base64 encoded text to the current position of the in
* progress XML document.
*
* @param b
* The binary data to add to the XML document.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
public XmlWriter value(ByteBuffer b) {
append(escapeXmlEntities(BinaryUtils.toBase64(BinaryUtils.copyBytesFrom(b))));
return this;
}
/**
* Adds the specified date as text to the current position of the
* in-progress XML document.
*
* @param date
* The date to add to the XML document.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
public XmlWriter value(Date date) {
append(escapeXmlEntities(DateUtils.formatIso8601Date(date.toInstant())));
return this;
}
/**
* Adds the string representation of the specified object to the current
* position of the in progress XML document.
*
* @param obj
* The object to translate to a string and add to the XML
* document.
*
* @return This XMLWriter so that additional method calls can be chained
* together.
*/
public XmlWriter value(Object obj) {
append(escapeXmlEntities(obj.toString()));
return this;
}
private void append(String s) {
try {
writer.append(s);
} catch (IOException e) {
throw SdkClientException.builder().message("Unable to write XML document").cause(e).build();
}
}
protected String escapeXmlEntities(String s) {
// Unescape any escaped characters.
if (s.contains("&")) {
s = StringUtils.replaceEach(s, UNESCAPE_SEARCHES, UNESCAPE_REPLACEMENTS);
}
return StringUtils.replaceEach(s, ESCAPE_SEARCHES, ESCAPE_REPLACEMENTS);
}
}