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/* * Copyright 2010-2013 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 cn.ctyun.amazonaws.util; import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; import java.net.URL; import java.nio.ByteBuffer; import java.text.ParseException; import java.util.Date; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory; import org.apache.commons.codec.binary.Base64; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import cn.ctyun.amazonaws.AmazonClientException; /** * Utility methods for extracting data from XML documents using Xpath * expressions. */ public class XpathUtils { private static XPathFactory xpathFactory = XPathFactory.newInstance(); private static XPath xpath = xpathFactory.newXPath(); /** Shared DateUtils object for parsing and formatting dates */ private static DateUtils dateUtils = new DateUtils(); /** Shared logger */ private static Log log = LogFactory.getLog(XpathUtils.class); private static DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); public static Document documentFrom(InputStream is) throws SAXException, IOException, ParserConfigurationException { is = new NamespaceRemovingInputStream(is); Document doc = factory.newDocumentBuilder().parse(is); is.close(); return doc; } public static Document documentFrom(String xml) throws SAXException, IOException, ParserConfigurationException { return documentFrom(new ByteArrayInputStream(xml.getBytes())); } public static Document documentFrom(URL url) throws SAXException, IOException, ParserConfigurationException { return documentFrom(url.openStream()); } /** * Evaluates the specified XPath expression and returns the results as a * Double. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Double result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Double asDouble(String expression, Node node) throws XPathExpressionException { String doubleString = evaluateAsString(expression, node); return (isEmptyString(doubleString)) ? null : Double.parseDouble(doubleString); } /** * Evaluates the specified XPath expression and returns the result as a * string. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The string result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static String asString(String expression, Node node) throws XPathExpressionException { return evaluateAsString(expression, node); } /** * Evaluates the specified XPath expression and returns the result as an * Integer. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Integer result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Integer asInteger(String expression, Node node) throws XPathExpressionException { String intString = evaluateAsString(expression, node); return (isEmptyString(intString)) ? null : Integer.parseInt(intString); } /** * Evaluates the specified XPath expression and returns the result as a * Boolean. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Boolean result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Boolean asBoolean(String expression, Node node) throws XPathExpressionException { String booleanString = evaluateAsString(expression, node); return (isEmptyString(booleanString)) ? null : Boolean.parseBoolean(booleanString); } /** * Evaluates the specified XPath expression and returns the result as a * Float. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Float result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Float asFloat(String expression, Node node) throws XPathExpressionException { String floatString = evaluateAsString(expression, node); return (isEmptyString(floatString)) ? null : Float.valueOf(floatString); } /** * Evaluates the specified XPath expression and returns the result as a * Long. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Long result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Long asLong(String expression, Node node) throws XPathExpressionException { String longString = evaluateAsString(expression, node); return (isEmptyString(longString)) ? null : Long.parseLong(longString); } /** * Evaluates the specified XPath expression and returns the result as a * Byte. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Byte result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Byte asByte(String expression, Node node) throws XPathExpressionException { String byteString = evaluateAsString(expression, node); return (isEmptyString(byteString)) ? null : Byte.valueOf(byteString); } /** * Evaluates the specified XPath expression and returns the result as a * Date. Assumes that the node's text is formatted as an ISO 8601 date, as * specified by xs:dateTime. * * @param expression * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Date result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Date asDate(String expression, Node node) throws XPathExpressionException { String dateString = evaluateAsString(expression, node); if (isEmptyString(dateString)) return null; try { return dateUtils.parseIso8601Date(dateString); } catch (ParseException e) { log.warn("Unable to parse date '" + dateString + "': " + e.getMessage(), e); return null; } } /** * Evaluates the specified xpath expression, base64 decodes the data and * returns the result as a ByteBuffer. * * @param expression * The Xpath expression to evaluate. * @param node * The node on which to evaluate the expression. * * @return A ByteBuffer of base64 decoded data from the result of evaluating * the specified Xpath expression. * * @throws XPathExpressionException * If there are any problems evaluating the Xpath expression. */ public static ByteBuffer asByteBuffer(String expression, Node node) throws XPathExpressionException { String base64EncodedString = evaluateAsString(expression, node); if (isEmptyString(base64EncodedString)) return null; if (!isEmpty(node)) { try { byte[] base64EncodedBytes = base64EncodedString.getBytes("UTF-8"); byte[] decodedBytes = Base64.decodeBase64(base64EncodedBytes); return ByteBuffer.wrap(decodedBytes); } catch (UnsupportedEncodingException e) { throw new AmazonClientException("Unable to unmarshall XML data into a ByteBuffer", e); } } return null; } /** * Returns true if the specified node is null or has no children. * * @param node * The node to test. * * @return True if the specified node is null or has no children. */ public static boolean isEmpty(Node node) { return (node == null); } /** * Evaluates the specified XPath expression and returns the result as a * Node. * * @param nodeName * The XPath expression to evaluate. * @param node * The node to run the expression on. * * @return The Node result. * * @throws XPathExpressionException * If there was a problem processing the specified XPath * expression. */ public static Node asNode(String nodeName, Node node) throws XPathExpressionException { if (node == null) return null; return (Node) xpath.evaluate(nodeName, node, XPathConstants.NODE); } /** * Returns the length of the specified node list. * * @param list * The node list to measure. * * @return The length of the specified node list. */ public static int nodeLength(NodeList list) { return list == null ? 0 : list.getLength(); } /** * Evaluates the specified expression on the specified node and returns the * result as a String. * * @param expression * The Xpath expression to evaluate. * @param node * The node on which to evaluate the expression. * * @return The result of evaluating the specified expression, or null if the * evaluation didn't return any result. * * @throws XPathExpressionException * If there are any problems evaluating the Xpath expression. */ private static String evaluateAsString(String expression, Node node) throws XPathExpressionException { if (isEmpty(node)) return null; if (expression != ".") { /* * If the expression being evaluated doesn't select a node, we want * to return null to distinguish between cases where a node isn't * present (which should be represented as null) and when a node is * present, but empty (which should be represented as the empty * string). * * We skip this test if the expression is "." since we've already * checked that the node exists. */ if (asNode(expression, node) == null) return null; } String s = xpath.evaluate(expression, node); return s.trim(); } /** * Returns true if the specified string is null or empty. * * @param s * The string to test. * @return True if the specified string is null or empty. */ private static boolean isEmptyString(String s) { if (s == null) return true; if (s.trim().equals("")) return true; return false; } }