INT-1155 initial commit for XPathTransformer

spring-integration-xml/src/main/java/org/springframework/integration/xml/transformer/XPathTransformer.java

@@ -0,0 +1,123 @@
+/*
+ * Copyright 2002-2010 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.integration.xml.transformer;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.w3c.dom.Node;
+
+import org.springframework.integration.core.Message;
+import org.springframework.integration.transformer.AbstractTransformer;
+import org.springframework.integration.xml.DefaultXmlPayloadConverter;
+import org.springframework.integration.xml.XmlPayloadConverter;
+import org.springframework.util.Assert;
+import org.springframework.xml.xpath.NodeMapper;
+import org.springframework.xml.xpath.XPathExpression;
+import org.springframework.xml.xpath.XPathExpressionFactory;
+
+/**
+ * Transformer implementation that evaluates an XPath expression against the inbound
+ * Message payload and returns a Message whose payload is the result of that evaluation.
+ * 
+ * @author Mark Fisher
+ * @since 2.0
+ */
+public class XPathTransformer extends AbstractTransformer {
+
+	public static enum ResultType {
+		BOOLEAN, NODE, NODELIST, NUMBER, OBJECT, STRING
+	}
+
+	private final XPathExpression xpathExpression;
+
+	private volatile XmlPayloadConverter converter = new DefaultXmlPayloadConverter();
+
+	private volatile ResultType expectedResultType = ResultType.STRING;
+
+	private volatile NodeMapper nodeMapper;
+
+
+	public XPathTransformer(String expression) {
+		this.xpathExpression = XPathExpressionFactory.createXPathExpression(expression);		
+	}
+
+	public XPathTransformer(String expression, Map<String, String> namespaces) {
+		this.xpathExpression = XPathExpressionFactory.createXPathExpression(expression, namespaces);
+	}
+
+	public XPathTransformer(String expression, String prefix, String namespace) {
+		Map<String, String> namespaces = new HashMap<String, String>();
+		namespaces.put(prefix, namespace);
+		this.xpathExpression = XPathExpressionFactory.createXPathExpression(expression, namespaces);
+	}
+
+
+	/**
+	 * Specify the expected {@link ResultType}. The default is {@link ResultType#STRING}.
+	 */
+	public void setExpectedResultType(ResultType expectedResultType) {
+		this.expectedResultType = expectedResultType;
+	}
+
+	/**
+	 * Set a {@link NodeMapper} to use for generating the result object.
+	 * This will also set the expectedResultType to <code>OBJECT</code> since
+	 * the actual type determination is a responsibility of the NodeMapper.
+	 */
+	public void setNodeMapper(NodeMapper nodeMapper) {
+		this.expectedResultType = ResultType.OBJECT;
+		this.nodeMapper = nodeMapper;
+	}
+
+	/**
+	 * Specify the {@link XmlPayloadConverter} to use when converting a Message payload prior to XPath evaluation.
+	 */
+	public void setConverter(XmlPayloadConverter converter) {
+		Assert.notNull(converter, "converter must not be null");
+		this.converter = converter;
+	}
+
+	@Override
+	protected Object doTransform(Message<?> message) throws Exception {
+		Node node = this.converter.convertToNode(message.getPayload());
+		Object result = null;
+		switch (this.expectedResultType) {
+			case BOOLEAN:
+				result = this.xpathExpression.evaluateAsBoolean(node);
+				break;
+			case NODE:
+				result = this.xpathExpression.evaluateAsNode(node);
+				break;
+			case NODELIST:
+				result = this.xpathExpression.evaluateAsNodeList(node);
+				break;
+			case NUMBER:
+				result = this.xpathExpression.evaluateAsNumber(node);
+				break;
+			case STRING:
+				result = this.xpathExpression.evaluateAsString(node);
+				break;
+			default: // works for OBJECT
+				Assert.notNull(this.nodeMapper, "NodeMapper required if expectedResultType is OBJECT");
+				result = this.xpathExpression.evaluateAsObject(node, this.nodeMapper);
+				break;
+		}
+		return result;
+	}
+
+}