org.chaston.oakfunds.bootstrap.BootstrapConfigReader.java Source code

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Here is the source code for org.chaston.oakfunds.bootstrap.BootstrapConfigReader.java

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/*
 * Copyright 2014 Miles Chaston
 *
 * 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.chaston.oakfunds.bootstrap;

import com.google.common.collect.ImmutableMap;
import com.google.inject.Inject;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import java.io.File;
import java.io.IOException;
import java.util.Set;

/**
 * TODO(mchaston): write JavaDocs
 */
class BootstrapConfigReader {

    private final ImmutableMap<String, BootstrapConfigLoader> configLoaders;

    @Inject
    BootstrapConfigReader(Set<BootstrapConfigLoader> configLoaders) {
        ImmutableMap.Builder<String, BootstrapConfigLoader> configLoadersBuilder = ImmutableMap.builder();
        for (BootstrapConfigLoader configLoader : configLoaders) {
            configLoadersBuilder.put(configLoader.getConfigElementName(), configLoader);
        }
        this.configLoaders = configLoadersBuilder.build();
    }

    public void read(File configFile) throws ParserConfigurationException, SAXException, IOException {
        SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
        SAXParser saxParser = saxParserFactory.newSAXParser();
        saxParser.parse(configFile, new BaseConfigHandler());
    }

    private class BaseConfigHandler extends DefaultHandler {
        private String currentElement;
        private DefaultHandler subHandler;

        @Override
        public void startElement(String uri, String localName, String qName, Attributes attributes)
                throws SAXException {
            if (subHandler != null) {
                subHandler.startElement(uri, localName, qName, attributes);
            } else if (qName.equals("boostrap_config")) {
                // Known wrapping element.
            } else {
                BootstrapConfigLoader configLoader = configLoaders.get(qName);
                if (configLoader == null) {
                    throw new SAXException("No handler for element " + qName + " was found.");
                }
                currentElement = qName;
                subHandler = configLoader.getDefaultHandler();
            }
        }

        @Override
        public void characters(char[] ch, int start, int length) throws SAXException {
            if (subHandler != null) {
                subHandler.characters(ch, start, length);
            }
        }

        @Override
        public void endElement(String uri, String localName, String qName) throws SAXException {
            if (currentElement != null && currentElement.equals(qName)) {
                currentElement = null;
                subHandler = null;
            }
        }
    }
}