Ant example source code file (Sync.java)

This example Ant source code file (Sync.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 - Ant tags/keywords

buildexception, buildexception, file, file, fileset, io, map, mycopy, no, pass, removing, removing, string, string, synctarget, util

The Sync.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.tools.ant.taskdefs;

import java.io.File;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.DirectoryScanner;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.AbstractFileSet;
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.types.PatternSet;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.selectors.FileSelector;
import org.apache.tools.ant.types.selectors.NoneSelector;

/**
 * Synchronize a local target directory from the files defined
 * in one or more filesets.
 *
 * <p>Uses a <copy> task internally, but forbidding the use of
 * mappers and filter chains. Files of the destination directory not
 * present in any of the source fileset are removed.</p>
 *
 * @since Ant 1.6
 *
 * revised by <a href="mailto:daniel.armbrust@mayo.edu">Dan Armbrust
 * to remove orphaned directories.
 *
 * @ant.task category="filesystem"
 */
public class Sync extends Task {

    // Same as regular <copy> task... see at end-of-file!
    private MyCopy myCopy;

    // Similar to a fileset, but doesn't allow dir attribute to be set
    private SyncTarget syncTarget;

    // Override Task#init
    /**
     * Initialize the sync task.
     * @throws BuildException if there is a problem.
     * @see Task#init()
     */
    public void init()
        throws BuildException {
        // Instantiate it
        myCopy = new MyCopy();
        configureTask(myCopy);

        // Default config of <mycopy> for our purposes.
        myCopy.setFiltering(false);
        myCopy.setIncludeEmptyDirs(false);
        myCopy.setPreserveLastModified(true);
    }

    private void configureTask(Task helper) {
        helper.setProject(getProject());
        helper.setTaskName(getTaskName());
        helper.setOwningTarget(getOwningTarget());
        helper.init();
    }

    // Override Task#execute
    /**
     * Execute the sync task.
     * @throws BuildException if there is an error.
     * @see Task#execute()
     */
    public void execute()
        throws BuildException {
        // The destination of the files to copy
        File toDir = myCopy.getToDir();

        // The complete list of files to copy
        Set allFiles = myCopy.nonOrphans;

        // If the destination directory didn't already exist,
        // or was empty, then no previous file removal is necessary!
        boolean noRemovalNecessary = !toDir.exists() || toDir.list().length < 1;

        // Copy all the necessary out-of-date files
        log("PASS#1: Copying files to " + toDir, Project.MSG_DEBUG);
        myCopy.execute();

        // Do we need to perform further processing?
        if (noRemovalNecessary) {
            log("NO removing necessary in " + toDir, Project.MSG_DEBUG);
            return; // nope ;-)
        }

        // Get rid of all files not listed in the source filesets.
        log("PASS#2: Removing orphan files from " + toDir, Project.MSG_DEBUG);
        int[] removedFileCount = removeOrphanFiles(allFiles, toDir);
        logRemovedCount(removedFileCount[0], "dangling director", "y", "ies");
        logRemovedCount(removedFileCount[1], "dangling file", "", "s");

        // Get rid of empty directories on the destination side
        if (!myCopy.getIncludeEmptyDirs()) {
            log("PASS#3: Removing empty directories from " + toDir,
                Project.MSG_DEBUG);
            int removedDirCount = removeEmptyDirectories(toDir, false);
            logRemovedCount(removedDirCount, "empty director", "y", "ies");
        }
    }

    private void logRemovedCount(int count, String prefix,
                                 String singularSuffix, String pluralSuffix) {
        File toDir = myCopy.getToDir();

        String what = (prefix == null) ? "" : prefix;
        what += (count < 2) ? singularSuffix : pluralSuffix;

        if (count > 0) {
            log("Removed " + count + " " + what + " from " + toDir,
                Project.MSG_INFO);
        } else {
            log("NO " + what + " to remove from " + toDir,
                Project.MSG_VERBOSE);
        }
    }

    /**
     * Removes all files and folders not found as keys of a table
     * (used as a set!).
     *
     * <p>If the provided file is a directory, it is recursively
     * scanned for orphaned files which will be removed as well.</p>
     *
     * <p>If the directory is an orphan, it will also be removed.

     *
     * @param  nonOrphans the table of all non-orphan <code>Files.
     * @param  file the initial file or directory to scan or test.
     * @return the number of orphaned files and directories actually removed.
     * Position 0 of the array is the number of orphaned directories.
     * Position 1 of the array is the number or orphaned files.
     */
    private int[] removeOrphanFiles(Set nonOrphans, File toDir) {
        int[] removedCount = new int[] {0, 0};
        String[] excls =
            (String[]) nonOrphans.toArray(new String[nonOrphans.size() + 1]);
        // want to keep toDir itself
        excls[nonOrphans.size()] = "";

        DirectoryScanner ds = null;
        if (syncTarget != null) {
            FileSet fs = new FileSet();
            fs.setDir(toDir);
            fs.setCaseSensitive(syncTarget.isCaseSensitive());
            fs.setFollowSymlinks(syncTarget.isFollowSymlinks());

            // preserveInTarget would find all files we want to keep,
            // but we need to find all that we want to delete - so the
            // meaning of all patterns and selectors must be inverted
            PatternSet ps = syncTarget.mergePatterns(getProject());
            fs.appendExcludes(ps.getIncludePatterns(getProject()));
            fs.appendIncludes(ps.getExcludePatterns(getProject()));
            fs.setDefaultexcludes(!syncTarget.getDefaultexcludes());

            // selectors are implicitly ANDed in DirectoryScanner.  To
            // revert their logic we wrap them into a <none> selector
            // instead.
            FileSelector[] s = syncTarget.getSelectors(getProject());
            if (s.length > 0) {
                NoneSelector ns = new NoneSelector();
                for (int i = 0; i < s.length; i++) {
                    ns.appendSelector(s[i]);
                }
                fs.appendSelector(ns);
            }
            ds = fs.getDirectoryScanner(getProject());
        } else {
            ds = new DirectoryScanner();
            ds.setBasedir(toDir);
        }
        ds.addExcludes(excls);

        ds.scan();
        String[] files = ds.getIncludedFiles();
        for (int i = 0; i < files.length; i++) {
            File f = new File(toDir, files[i]);
            log("Removing orphan file: " + f, Project.MSG_DEBUG);
            f.delete();
            ++removedCount[1];
        }
        String[] dirs = ds.getIncludedDirectories();
        // ds returns the directories in lexicographic order.
        // iterating through the array backwards means we are deleting
        // leaves before their parent nodes - thus making sure (well,
        // more likely) that the directories are empty when we try to
        // delete them.
        for (int i = dirs.length - 1; i >= 0; --i) {
            File f = new File(toDir, dirs[i]);
            if (f.list().length < 1) {
            log("Removing orphan directory: " + f, Project.MSG_DEBUG);
            f.delete();
            ++removedCount[0];
            }
        }
        return removedCount;
    }

    /**
     * Removes all empty directories from a directory.
     *
     * <p>Note that a directory that contains only empty
     * directories, directly or not, will be removed!</em>

     *
     * <p>Recurses depth-first to find the leaf directories
     * which are empty and removes them, then unwinds the
     * recursion stack, removing directories which have
     * become empty themselves, etc...</p>
     *
     * @param  dir the root directory to scan for empty directories.
     * @param  removeIfEmpty whether to remove the root directory
     *         itself if it becomes empty.
     * @return the number of empty directories actually removed.
     */
    private int removeEmptyDirectories(File dir, boolean removeIfEmpty) {
        int removedCount = 0;
        if (dir.isDirectory()) {
            File[] children = dir.listFiles();
            for (int i = 0; i < children.length; ++i) {
                File file = children[i];
                // Test here again to avoid method call for non-directories!
                if (file.isDirectory()) {
                    removedCount += removeEmptyDirectories(file, true);
                }
            }
            if (children.length > 0) {
                // This directory may have become empty...
                // We need to re-query its children list!
                children = dir.listFiles();
            }
            if (children.length < 1 && removeIfEmpty) {
                log("Removing empty directory: " + dir, Project.MSG_DEBUG);
                dir.delete();
                ++removedCount;
            }
        }
        return removedCount;
    }


    //
    // Various copy attributes/subelements of <copy> passed thru to 
    //

    /**
     * Sets the destination directory.
     * @param destDir the destination directory
     */
    public void setTodir(File destDir) {
        myCopy.setTodir(destDir);
    }

    /**
     * Used to force listing of all names of copied files.
     * @param verbose if true force listing of all names of copied files.
     */
    public void setVerbose(boolean verbose) {
        myCopy.setVerbose(verbose);
    }

    /**
     * Overwrite any existing destination file(s).
     * @param overwrite if true overwrite any existing destination file(s).
     */
    public void setOverwrite(boolean overwrite) {
        myCopy.setOverwrite(overwrite);
    }

    /**
     * Used to copy empty directories.
     * @param includeEmpty If true copy empty directories.
     */
    public void setIncludeEmptyDirs(boolean includeEmpty) {
        myCopy.setIncludeEmptyDirs(includeEmpty);
    }

    /**
     * If false, note errors to the output but keep going.
     * @param failonerror true or false
     */
    public void setFailOnError(boolean failonerror) {
        myCopy.setFailOnError(failonerror);
    }

    /**
     * Adds a set of files to copy.
     * @param set a fileset
     */
    public void addFileset(FileSet set) {
        add(set);
    }

    /**
     * Adds a collection of filesystem resources to copy.
     * @param rc a resource collection
     * @since Ant 1.7
     */
    public void add(ResourceCollection rc) {
        myCopy.add(rc);
    }

    /**
     * The number of milliseconds leeway to give before deciding a
     * target is out of date.
     *
     * <p>Default is 0 milliseconds, or 2 seconds on DOS systems.

     * @param granularity a <code>long value
     * @since Ant 1.6.2
     */
    public void setGranularity(long granularity) {
        myCopy.setGranularity(granularity);
    }

    /**
     * A container for patterns and selectors that can be used to
     * specify files that should be kept in the target even if they
     * are not present in any source directory.
     *
     * <p>You must not invoke this method more than once.

     * @param s a preserveintarget nested element
     * @since Ant 1.7
     */
    public void addPreserveInTarget(SyncTarget s) {
        if (syncTarget != null) {
            throw new BuildException("you must not specify multiple "
                                     + "preserveintarget elements.");
        }
        syncTarget = s;
    }

    /**
     * Subclass Copy in order to access it's file/dir maps.
     */
    public static class MyCopy extends Copy {

        // List of files that must be copied, irrelevant from the
        // fact that they are newer or not than the destination.
        private Set nonOrphans = new HashSet();

        /** Constructor for MyCopy. */
        public MyCopy() {
        }

        /**
         * @see Copy#scan(File, File, String[], String[])
         */
        /** {@inheritDoc} */
        protected void scan(File fromDir, File toDir, String[] files,
                            String[] dirs) {
            assertTrue("No mapper", mapperElement == null);

            super.scan(fromDir, toDir, files, dirs);

            for (int i = 0; i < files.length; ++i) {
                nonOrphans.add(files[i]);
            }
            for (int i = 0; i < dirs.length; ++i) {
                nonOrphans.add(dirs[i]);
            }
        }

        /**
         * @see Copy#scan(Resource[], File)
         */
        /** {@inheritDoc} */
        protected Map scan(Resource[] resources, File toDir) {
            assertTrue("No mapper", mapperElement == null);

            Map m = super.scan(resources, toDir);

            Iterator iter = m.keySet().iterator();
            while (iter.hasNext()) {
                nonOrphans.add(((Resource) iter.next()).getName());
            }
            return m;
        }

        /**
         * Get the destination directory.
         * @return the destination directory
         */
        public File getToDir() {
            return destDir;
        }

        /**
         * Get the includeEmptyDirs attribute.
         * @return true if emptyDirs are to be included
         */
        public boolean getIncludeEmptyDirs() {
            return includeEmpty;
        }

        /**
         * Yes, we can.
         * @return true always.
         * @since Ant 1.7
         */
        protected boolean supportsNonFileResources() {
            return true;
        }
    }

    /**
     * Inner class used to hold exclude patterns and selectors to save
     * stuff that happens to live in the target directory but should
     * not get removed.
     *
     * @since Ant 1.7
     */
    public static class SyncTarget extends AbstractFileSet {

        /**
         * Constructor for SyncTarget.
         * This just changes the default value of "defaultexcludes" from
         * true to false.
         */
        public SyncTarget() {
            super();
        }

        /**
         * Override AbstractFileSet#setDir(File) to disallow
         * setting the directory.
         * @param dir ignored
         * @throws BuildException always
         */
        public void setDir(File dir) throws BuildException {
            throw new BuildException("preserveintarget doesn't support the dir "
                                     + "attribute");
        }

    }

    /**
     * Pseudo-assert method.
     */
    private static void assertTrue(String message, boolean condition) {
        if (!condition) {
            throw new BuildException("Assertion Error: " + message);
        }
    }

}