org.apache.stratos.autoscaler.policy.deployers.AbstractPolicyReader.java Source code

Introduction

Here is the source code for org.apache.stratos.autoscaler.policy.deployers.AbstractPolicyReader.java

Source

/*
 * 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.stratos.autoscaler.policy.deployers;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamReader;

import org.apache.axiom.om.OMElement;
import org.apache.axiom.om.impl.builder.StAXOMBuilder;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.stratos.autoscaler.exception.InvalidPolicyException;

/**
 * Abstract super-class, with some common logic, for reading policies. The only
 * method subclasses must implement is read().
 */
public abstract class AbstractPolicyReader<T> {

    private static final Log log = LogFactory.getLog(AbstractPolicyReader.class);

    protected File file;
    private FileInputStream fStream;

    protected AbstractPolicyReader(File file) {
        this.setFile(file);
    }

    public File getFile() {
        return file;
    }

    public void setFile(File file) {
        this.file = file;
    }

    public abstract T read() throws InvalidPolicyException;

    protected OMElement getDocument() throws Exception {
        fStream = new FileInputStream(file);
        XMLStreamReader parser = XMLInputFactory.newInstance().createXMLStreamReader(fStream);
        StAXOMBuilder builder = new StAXOMBuilder(parser);
        return builder.getDocumentElement();
    }

    protected void closeStream() {
        try {
            if (fStream != null) {
                fStream.close();
            }
        } catch (IOException e) {
            log.debug("Unable to close the input stream", e);
        }
    }

    protected String readValueAttr(OMElement ele, String qName) {
        OMElement valueContainer = ele.getFirstChildWithName(new QName(qName));
        String value = valueContainer.getAttributeValue(new QName("value"));
        return value;
    }

    protected String readValue(OMElement ele, String qName) {
        OMElement valueContainer = ele.getFirstChildWithName(new QName(qName));
        if (valueContainer == null) {
            return null;
        }
        String value = valueContainer.getText();
        return value;
    }

}