Package org.apache.camel.scr

Source Code of org.apache.camel.scr.ScrHelper

/**
* 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.
*/
package org.apache.camel.scr;

import java.io.File;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

/**
* Helper class.
*/
public final class ScrHelper {

    private static final Logger LOG = LoggerFactory.getLogger(ScrHelper.class);

    private ScrHelper() {
    }

    public static Map<String, String> getScrProperties(String componentName) throws Exception {
        return getScrProperties(String.format("target/classes/OSGI-INF/%s.xml", componentName), componentName);
    }

    public static Map<String, String> getScrProperties(String xmlLocation, String componentName) throws Exception {
        Map<String, String> result = new HashMap<String, String>();
        final Document dom = readXML(new File(xmlLocation));
        final XPath xPath = XPathFactory.newInstance(XPathFactory.DEFAULT_OBJECT_MODEL_URI, "com.sun.org.apache.xpath.internal.jaxp.XPathFactoryImpl", null).newXPath();
        xPath.setNamespaceContext(new NamespaceContext() {
            @Override
            public String getNamespaceURI(String prefix) {
                switch (prefix) {
                    case "scr":
                        try {
                            XPathExpression scrNamespace = xPath.compile("/*/namespace::*[name()='scr']");
                            Node node = (Node) scrNamespace.evaluate(dom, XPathConstants.NODE);
                            return node.getNodeValue();
                        } catch (XPathExpressionException e) {
                            // ignore
                            LOG.debug("Error evaluating xpath to obtain namespace prefix. This exception is ignored and using namespace: http://www.osgi.org/xmlns/scr/v1.1.0", e);

                        }
                        return "http://www.osgi.org/xmlns/scr/v1.1.0";
                    default:
                        // noop
                }
                return XMLConstants.NULL_NS_URI;
            }

            @Override
            public String getPrefix(String namespaceURI) {
                return null;
            }

            @Override
            public Iterator getPrefixes(String namespaceURI) {
                return null;
            }
        });

        String propertyListExpression = String.format("/components/scr:component[@name='%s']/property", componentName);
        XPathExpression propertyList = xPath.compile(propertyListExpression);
        XPathExpression propertyName = xPath.compile("@name");
        XPathExpression propertyValue = xPath.compile("@value");
        NodeList nodes = (NodeList) propertyList.evaluate(dom, XPathConstants.NODESET);
        for (int i = 0; i < nodes.getLength(); i++) {
            Node node = nodes.item(i);
            result.put((String) propertyName.evaluate(node, XPathConstants.STRING), (String) propertyValue.evaluate(node, XPathConstants.STRING));
        }
        return result;
    }

    private static Document readXML(File xml) throws Exception {
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        builderFactory.setNamespaceAware(true);
        DocumentBuilder builder = builderFactory.newDocumentBuilder();
        return builder.parse(xml);
    }

}
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