src/jdk.jfr/share/classes/jdk/jfr/internal/jfc/JFCParserHandler.java

/*
 * Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package jdk.jfr.internal.jfc;
import java.util.LinkedHashMap;
import java.util.Map;

import jdk.internal.org.xml.sax.Attributes;
import jdk.internal.org.xml.sax.SAXException;
import jdk.internal.org.xml.sax.helpers.DefaultHandler;

final class JFCParserHandler extends DefaultHandler {
    private static final String ELEMENT_CONFIGURATION = "configuration";
    private static final String ELEMENT_EVENT_TYPE = "event";
    private static final String ELEMENT_SETTING = "setting";
    private static final String ATTRIBUTE_NAME = "name";
    private static final String ATTRIBUTE_LABEL = "label";
    private static final String ATTRIBUTE_DESCRIPTION = "description";
    private static final String ATTRIBUTE_PROVIDER = "provider";
    private static final String ATTRIBUTE_VERSION = "version";

    final Map<String, String> settings = new LinkedHashMap<String, String>();
    private String currentEventPath;
    private String currentSettingsName;
    private StringBuilder currentCharacters;
    String label;
    String provider;
    String description;

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        switch (qName.toLowerCase()) {
        case ELEMENT_CONFIGURATION:
            String version = attributes.getValue(ATTRIBUTE_VERSION);
            if (version == null || !version.startsWith("2.")) {
               throw new SAXException("This version of Flight Recorder can only read JFC file format version 2.x");
            }
            label = attributes.getValue(ATTRIBUTE_LABEL);
            description = getOptional(attributes, ATTRIBUTE_DESCRIPTION, "");
            provider = getOptional(attributes, ATTRIBUTE_PROVIDER, "");
            break;
        case ELEMENT_EVENT_TYPE:
            currentEventPath = attributes.getValue(ATTRIBUTE_NAME);
            break;
        case ELEMENT_SETTING:
            currentSettingsName = attributes.getValue(ATTRIBUTE_NAME);
            break;
        }
        currentCharacters = null;
    }

    private String getOptional(Attributes attributes, String name, String defaultValue) {
        String value = attributes.getValue(name);
        return value == null ? defaultValue : value;
    }

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

    @Override
    public void endElement(String uri, String localName, String qName) {
        switch (qName.toLowerCase()) {
        case ELEMENT_CONFIGURATION:
            break;
        case ELEMENT_EVENT_TYPE:
            currentEventPath = null;
            break;
        case ELEMENT_SETTING:
            String settingsValue = currentCharacters == null ? "" : currentCharacters.toString();
            settings.put(currentEventPath + "#" + currentSettingsName, "" + settingsValue);
            currentSettingsName = null;
            break;
        }
    }

    public Map<String, String> getSettings() {
        return settings;
    }
}