Ant example source code file (DependSet.java)

This example Ant source code file (DependSet.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, hidemissingbasedir, io, nonexistent, path, resource, resourcecollection, resourcecomparator, resourcecomparator, restrict, restrict, union, util, xest, xest

The DependSet.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.Iterator;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.FileSet;
import org.apache.tools.ant.types.FileList;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.TimeComparison;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.resources.Sort;
import org.apache.tools.ant.types.resources.Union;
import org.apache.tools.ant.types.resources.Restrict;
import org.apache.tools.ant.types.resources.Resources;
import org.apache.tools.ant.types.resources.FileResource;
import org.apache.tools.ant.types.resources.selectors.Not;
import org.apache.tools.ant.types.resources.selectors.Exists;
import org.apache.tools.ant.types.resources.selectors.ResourceSelector;
import org.apache.tools.ant.types.resources.comparators.Reverse;
import org.apache.tools.ant.types.resources.comparators.ResourceComparator;

/**
 * Examines and removes out of date target files.  If any of the target files
 * are out of date with respect to any of the source files, all target
 * files are removed.  This is useful where dependencies cannot be
 * computed (for example, dynamically interpreted parameters or files
 * that need to stay in synch but are not directly linked) or where
 * the ant task in question could compute them but does not (for
 * example, the linked DTD for an XML file using the XSLT task).
 *
 * nested arguments:
 * <ul>
 * <li>sources        (resource union describing the source resources to examine)
 * <li>srcfileset     (fileset describing the source files to examine)
 * <li>srcfilelist    (filelist describing the source files to examine)
 * <li>targets        (path describing the target files to examine)
 * <li>targetfileset  (fileset describing the target files to examine)
 * <li>targetfilelist (filelist describing the target files to examine)
 * </ul>
 * At least one of both source and target entities is required.
 * <p>
 * This task will examine each of the sources against each of the target files. If
 * any target files are out of date with respect to any of the sources, all targets
 * are removed. If any sources or targets do not exist, all targets are removed.
 * Hint: If missing files should be ignored, specify them as include patterns
 * in filesets, rather than using filelists.
 * </p>

 * This task attempts to optimize speed of dependency checking
 * by comparing only the dates of the oldest target file and the newest source.
 * </p>

 * Example uses:
 * <ul>

 * Record the fact that an XML file must be up to date with respect to its XSD
 * (Schema file), even though the XML file itself includes no reference to its XSD.
 * </li>

 * Record the fact that an XSL stylesheet includes other sub-stylesheets
 * </li>

 * Record the fact that java files must be recompiled if the ant build file changes
 * </li>
 *
 * @ant.task category="filesystem"
 * @since Ant 1.4
 */
public class DependSet extends MatchingTask {

    private static final ResourceSelector NOT_EXISTS = new Not(new Exists());
    private static final ResourceComparator DATE_ASC
        = new org.apache.tools.ant.types.resources.comparators.Date();
    private static final ResourceComparator DATE_DESC = new Reverse(DATE_ASC);

    private static class NonExistent extends Restrict {
        private NonExistent(ResourceCollection rc) {
            super.add(rc);
            super.add(NOT_EXISTS);
        }
    }
    private static class Xest extends Sort {
        private Xest(ResourceCollection rc, ResourceComparator c) {
            super.add(c);
            super.add(rc);
        }
    }
    private static class Oldest extends Xest {
        private Oldest(ResourceCollection rc) {
            super(rc, DATE_ASC);
        }
    }
    private static class Newest extends Xest {
        private Newest(ResourceCollection rc) {
            super(rc, DATE_DESC);
        }
    }
    private static class HideMissingBasedir implements ResourceCollection {
        private FileSet fs;

        private HideMissingBasedir(FileSet fs) {
            this.fs = fs;
        }
        public Iterator iterator() {
            return basedirExists() ? fs.iterator() : Resources.EMPTY_ITERATOR;
        }
        public int size() {
            return basedirExists() ? fs.size() : 0;
        }
        public boolean isFilesystemOnly() {
            return true;
        }
        private boolean basedirExists() {
            File basedir = fs.getDir();
            //trick to evoke "basedir not set" if null:
            return basedir == null || basedir.exists();
        }
    }

    private Union sources = null;
    private Path targets = null;

    /**
     * Create a nested sources element.
     * @return a Union instance.
     */
    public synchronized Union createSources() {
        sources = (sources == null) ? new Union() : sources;
        return sources;
    }

    /**
     * Add a set of source files.
     * @param fs the FileSet to add.
     */
    public void addSrcfileset(FileSet fs) {
        createSources().add(fs);
    }

    /**
     * Add a list of source files.
     * @param fl the FileList to add.
     */
    public void addSrcfilelist(FileList fl) {
        createSources().add(fl);
    }

    /**
     * Create a nested targets element.
     * @return a Union instance.
     */
    public synchronized Path createTargets() {
        targets = (targets == null) ? new Path(getProject()) : targets;
        return targets;
    }

    /**
     * Add a set of target files.
     * @param fs the FileSet to add.
     */
    public void addTargetfileset(FileSet fs) {
        createTargets().add(new HideMissingBasedir(fs));
    }

    /**
     * Add a list of target files.
     * @param fl the FileList to add.
     */
    public void addTargetfilelist(FileList fl) {
        createTargets().add(fl);
    }

    /**
     * Execute the task.
     * @throws BuildException if errors occur.
     */
    public void execute() throws BuildException {
        if (sources == null) {
          throw new BuildException(
              "At least one set of source resources must be specified");
        }
        if (targets == null) {
          throw new BuildException(
              "At least one set of target files must be specified");
        }
        //no sources = nothing to compare; no targets = nothing to delete:
        if (sources.size() > 0 && targets.size() > 0 && !uptodate(sources, targets)) {
           log("Deleting all target files.", Project.MSG_VERBOSE);
           Delete delete = new Delete();
           delete.bindToOwner(this);
           delete.add(targets);
           delete.perform();
        }
    }

    private boolean uptodate(ResourceCollection src, ResourceCollection target) {
        org.apache.tools.ant.types.resources.selectors.Date datesel
            = new org.apache.tools.ant.types.resources.selectors.Date();
        datesel.setMillis(System.currentTimeMillis());
        datesel.setWhen(TimeComparison.AFTER);
        logFuture(targets, datesel);

        int neTargets = new NonExistent(targets).size();
        if (neTargets > 0) {
            log(neTargets + " nonexistent targets", Project.MSG_VERBOSE);
            return false;
        }
        FileResource oldestTarget = (FileResource) (new Oldest(targets).iterator().next());
        log(oldestTarget + " is oldest target file", Project.MSG_VERBOSE);

        logFuture(sources, datesel);

        int neSources = new NonExistent(sources).size();
        if (neSources > 0) {
            log(neSources + " nonexistent sources", Project.MSG_VERBOSE);
            return false;
        }
        Resource newestSource = (Resource) (new Newest(sources).iterator().next());
        log(newestSource.toLongString() + " is newest source", Project.MSG_VERBOSE);
        return oldestTarget.getLastModified() >= newestSource.getLastModified();
    }

    private void logFuture(ResourceCollection rc, ResourceSelector rsel) {
        Restrict r = new Restrict();
        r.add(rsel);
        r.add(rc);
        for (Iterator i = r.iterator(); i.hasNext();) {
            log("Warning: " + i.next() + " modified in the future.", Project.MSG_WARN);
        }
    }
}