jelly-tags/memory/src/java/org/apache/commons/jelly/tags/memory/FreeMemoryTag.java

/*
 * Copyright 2002,2005 The Apache Software Foundation.
 *
 * 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.apache.commons.jelly.tags.memory;

import org.apache.commons.jelly.JellyTagException;
import org.apache.commons.jelly.TagSupport;
import org.apache.commons.jelly.XMLOutput;

/**
 * Tag supporting displaying free memory.
 *
 * @author <a href="mailto:brett@apache.org">Brett Porter</a>
 */
public class FreeMemoryTag extends TagSupport {

    private static final int MB = 1024 * 1024;
    private static final int KB = 1024;

    private String style = "mb";

    public void setStyle(String style) {
        if (style == null) {
            style = "mb";
        }
        this.style = style.toLowerCase();
    }

    public String getStyle() {
        return this.style;
    }
 
    // Tag interface
    //-------------------------------------------------------------------------
    public void doTag(XMLOutput output) throws JellyTagException {

        Runtime r = Runtime.getRuntime();

        try {
            long total = r.totalMemory();
            long free = total - r.freeMemory();

            if (style.equals("kb")) {
                free /= KB;
                total /= KB;
            }
            else if (style.equals("mb")) {
                free /= MB;
                total /= MB;
            }
            
            output.write( free + style + "/" + total + style );
        }
        catch ( Exception e ) {
            throw new JellyTagException( "Error writing to output", e );
        }
    }

}