Java XPath Evaluate evaluateXPathExpr(final File xmlFile, final XPathExpression xPathExpression, final QName returnType)

Description

Evaluates the passed XPathExpression against the Document created out of the passed xmlFile and returns the result of the evaluation.

License

Apache License

Parameter

Parameter	Description
xmlFile	The XML file to parse
xPathExpression	The XPath expression to evaluate
returnType	The expected return type of the XPathExpression#evaluate(Object,QName) evaluation

Exception

Parameter	Description
Exception	if something goes wrong

Return

The result

Declaration

public static Object evaluateXPathExpr(final File xmlFile, final XPathExpression xPathExpression,
        final QName returnType) throws Exception 

Method Source Code

//package com.java2s;
/*//from  w  w  w .j ava 2 s  .c o  m
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.
 *
 */

import java.io.File;
import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;

public class Main {
    /**
     * Evaluates the passed {@link XPathExpression} against the {@link Document} created out of the
     * passed <code>xmlFile</code> and returns the result of the evaluation.
     *
     * @param xmlFile         The XML file to parse
     * @param xPathExpression The XPath expression to evaluate
     * @param returnType      The expected return type of the {@link XPathExpression#evaluate(Object, QName) evaluation}
     * @return                The result
     * @throws Exception if something goes wrong
     */
    public static Object evaluateXPathExpr(final File xmlFile, final XPathExpression xPathExpression,
            final QName returnType) throws Exception {
        if (xmlFile == null) {
            throw new IllegalArgumentException("XML file cannot be null");
        }
        if (!xmlFile.isFile()) {
            throw new IllegalArgumentException(xmlFile + " is either missing or not a file");
        }
        if (xPathExpression == null) {
            throw new IllegalArgumentException("XPath expression cannot be null");
        }
        final DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        final Document document = documentBuilder.parse(xmlFile);
        return xPathExpression.evaluate(document, returnType);
    }

    /**
     * Evaluates the passed <code>xpathExpression</code> against the {@link Document} created out of
     * the passed <code>xmlFile</code> and returns the result of the evaluation. This is the same as
     * calling {@link #evaluateXPathExpr(File, XPathExpression, QName)}, with
     * <code>XPathFactory.newInstance().newXPath().compile(xpathExpression)</code> as the
     * {@link XPathExpression} parameter
     *
     * @param xmlFile         The XML file to parse
     * @param xpathExpression The XPath expression to evaluate
     * @param returnType      The expected return type of the {@link XPathExpression#evaluate(Object, QName) evaluation}
     * @return                The result
     * @throws Exception if something goes wrong
     */
    public static Object evaluateXPathExpr(final File xmlFile, final String xpathExpression, final QName returnType)
            throws Exception {
        return evaluateXPathExpr(xmlFile, XPathFactory.newInstance().newXPath().compile(xpathExpression),
                returnType);
    }
}

Related

1. evaluateXpath(String expression, Object node, QName returnType, NamespaceContext nsContext)
2. evaluateXPath(String path, Node e, QName type)
3. evaluateXPath(String xpath, Object item, QName returnType)
4. evaluateXPathAsNodeList(String expression, Document document)
5. evaluateXPathBool(final Node inNode, final String xpath)
6. evaluateXPathExpr(XPathExpression xpath, Node node)
7. evaluateXPathExpression(final String expression, final Node node)
8. evaluateXPathExpressionAndReturnNode(String expression, Node node)
9. evaluateXPathExpressionAndReturnNodeList(String expression, Node node)