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Tomcat example source code file (WarWatcher.java)

This example Tomcat source code file (WarWatcher.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

file, file, filechangelistener, hashmap, io, iterator, map, string, util, warfilter, warfilter, warinfo, warinfo, warwatcher, warwatcher

The Tomcat WarWatcher.java source code

/*
 * 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.catalina.ha.deploy;

import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.Iterator;

/**
 * <p>
 * The <b>WarWatcher  watches the deployDir for changes made to the
 * directory (adding new WAR files->deploy or remove WAR files->undeploy) And
 * notifies a listener of the changes made
 * </p>
 * 
 * @author Filip Hanik
 * @author Peter Rossbach
 * @version 1.1
 */

public class WarWatcher {

    /*--Static Variables----------------------------------------*/
    public static org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
            .getLog(WarWatcher.class);

    /*--Instance Variables--------------------------------------*/
    /**
     * Directory to watch for war files
     */
    protected File watchDir = null;

    /**
     * Parent to be notified of changes
     */
    protected FileChangeListener listener = null;

    /**
     * Currently deployed files
     */
    protected Map currentStatus = new HashMap();

    /*--Constructor---------------------------------------------*/

    public WarWatcher() {
    }

    public WarWatcher(FileChangeListener listener, File watchDir) {
        this.listener = listener;
        this.watchDir = watchDir;
    }

    /*--Logic---------------------------------------------------*/

    /**
     * check for modification and send notifcation to listener
     */
    public void check() {
        if (log.isInfoEnabled())
            log.info("check cluster wars at " + watchDir);
        File[] list = watchDir.listFiles(new WarFilter());
        if (list == null)
            list = new File[0];
        //first make sure all the files are listed in our current status
        for (int i = 0; i < list.length; i++) {
            addWarInfo(list[i]);
        }

        //check all the status codes and update the FarmDeployer
        for (Iterator i = currentStatus.entrySet().iterator(); i.hasNext();) {
            Map.Entry entry = (Map.Entry) i.next();
            WarInfo info = (WarInfo) entry.getValue();
            int check = info.check();
            if (check == 1) {
                listener.fileModified(info.getWar());
            } else if (check == -1) {
                listener.fileRemoved(info.getWar());
                //no need to keep in memory
                currentStatus.remove(info.getWar());
            }
        }

    }

    /**
     * add cluster war to the watcher state
     * @param warfile
     */
    protected void addWarInfo(File warfile) {
        WarInfo info = (WarInfo) currentStatus.get(warfile.getAbsolutePath());
        if (info == null) {
            info = new WarInfo(warfile);
            info.setLastState(-1); //assume file is non existent
            currentStatus.put(warfile.getAbsolutePath(), info);
        }
    }

    /**
     * clear watcher state
     */
    public void clear() {
        currentStatus.clear();
    }

    /**
     * @return Returns the watchDir.
     */
    public File getWatchDir() {
        return watchDir;
    }

    /**
     * @param watchDir
     *            The watchDir to set.
     */
    public void setWatchDir(File watchDir) {
        this.watchDir = watchDir;
    }

    /**
     * @return Returns the listener.
     */
    public FileChangeListener getListener() {
        return listener;
    }

    /**
     * @param listener
     *            The listener to set.
     */
    public void setListener(FileChangeListener listener) {
        this.listener = listener;
    }

    /*--Inner classes-------------------------------------------*/

    /**
     * File name filter for war files
     */
    protected class WarFilter implements java.io.FilenameFilter {
        public boolean accept(File path, String name) {
            if (name == null)
                return false;
            return name.endsWith(".war");
        }
    }

    /**
     * File information on existing WAR files
     */
    protected class WarInfo {
        protected File war = null;

        protected long lastChecked = 0;

        protected long lastState = 0;

        public WarInfo(File war) {
            this.war = war;
            this.lastChecked = war.lastModified();
            if (!war.exists())
                lastState = -1;
        }

        public boolean modified() {
            return war.exists() && war.lastModified() > lastChecked;
        }

        public boolean exists() {
            return war.exists();
        }

        /**
         * Returns 1 if the file has been added/modified, 0 if the file is
         * unchanged and -1 if the file has been removed
         * 
         * @return int 1=file added; 0=unchanged; -1=file removed
         */
        public int check() {
            //file unchanged by default
            int result = 0;

            if (modified()) {
                //file has changed - timestamp
                result = 1;
                lastState = result;
            } else if ((!exists()) && (!(lastState == -1))) {
                //file was removed
                result = -1;
                lastState = result;
            } else if ((lastState == -1) && exists()) {
                //file was added
                result = 1;
                lastState = result;
            }
            this.lastChecked = System.currentTimeMillis();
            return result;
        }

        public File getWar() {
            return war;
        }

        public int hashCode() {
            return war.getAbsolutePath().hashCode();
        }

        public boolean equals(Object other) {
            if (other instanceof WarInfo) {
                WarInfo wo = (WarInfo) other;
                return wo.getWar().equals(getWar());
            } else {
                return false;
            }
        }

        protected void setLastState(int lastState) {
            this.lastState = lastState;
        }

    }

}

Other Tomcat examples (source code examples)

Here is a short list of links related to this Tomcat WarWatcher.java source code file:

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