Ant example source code file (Resources.java)

This example Ant source code file (Resources.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

datatype, empty_iterator, io, iterator, iterator, mycollection, mycollection, myiterator, object, object, resourcecollection, resourcecollection, stringbuffer, unsupportedoperationexception, util, vector

The Resources.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.types.resources;

import java.io.File;
import java.util.List;
import java.util.Stack;
import java.util.Vector;
import java.util.Iterator;
import java.util.Collection;
import java.util.Collections;
import java.util.AbstractCollection;
import java.util.NoSuchElementException;

import org.apache.tools.ant.Project;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.types.DataType;
import org.apache.tools.ant.types.ResourceCollection;

/**
 * Generic ResourceCollection: Either stores nested ResourceCollections,
 * making no attempt to remove duplicates, or references another ResourceCollection.
 * @since Ant 1.7
 */
public class Resources extends DataType implements ResourceCollection {
    /** static empty ResourceCollection */
    public static final ResourceCollection NONE = new ResourceCollection() {
        public boolean isFilesystemOnly() {
            return true;
        }
        public Iterator iterator() {
            return EMPTY_ITERATOR;
        }
        public int size() {
            return 0;
        }
    };

    /** static empty Iterator */
    public static final Iterator EMPTY_ITERATOR = new Iterator() {
        public Object next() {
            throw new NoSuchElementException();
        }
        public boolean hasNext() {
            return false;
        }
        public void remove() {
            throw new UnsupportedOperationException();
        }
    };

    private class MyCollection extends AbstractCollection {
        private int size;

        MyCollection() {
            size = 0;
            for (Iterator rci = getNested().iterator(); rci.hasNext();) {
                size += ((ResourceCollection) rci.next()).size();
            }
        }
        public int size() {
            return size;
        }
        public Iterator iterator() {
            return new MyIterator();
        }
        private class MyIterator implements Iterator {
            private Iterator rci = getNested().iterator();
            private Iterator ri = null;

            public boolean hasNext() {
                boolean result = ri != null && ri.hasNext();
                while (!result && rci.hasNext()) {
                    ri = ((ResourceCollection) rci.next()).iterator();
                    result = ri.hasNext();
                }
                return result;
            }
            public Object next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                return ri.next();
            }
            public void remove() {
                throw new UnsupportedOperationException();
            }
        }
    }

    private Vector rc;
    private Collection coll;

    /**
     * Add a ResourceCollection.
     * @param c the ResourceCollection to add.
     */
    public synchronized void add(ResourceCollection c) {
        if (isReference()) {
            throw noChildrenAllowed();
        }
        if (c == null) {
            return;
        }
        if (rc == null) {
            rc = new Vector();
        }
        rc.add(c);
        FailFast.invalidate(this);
        coll = null;
        setChecked(false);
    }

    /**
     * Fulfill the ResourceCollection contract.
     * @return an Iterator of Resources.
     */
    public synchronized Iterator iterator() {
        if (isReference()) {
            return getRef().iterator();
        }
        validate();
        return new FailFast(this, coll.iterator());
    }

    /**
     * Fulfill the ResourceCollection contract.
     * @return number of elements as int.
     */
    public synchronized int size() {
        if (isReference()) {
            return getRef().size();
        }
        validate();
        return coll.size();
    }

    /**
     * Fulfill the ResourceCollection contract.
     * @return true if all Resources represent files.
     */
    public boolean isFilesystemOnly() {
        if (isReference()) {
            return getRef().isFilesystemOnly();
        }
        validate();

        for (Iterator i = getNested().iterator(); i.hasNext();) {
            if ((!((ResourceCollection) i.next()).isFilesystemOnly())) {
                return false;
            }
        }
        return true;
    }

    /**
     * Format this BaseResourceCollectionContainer as a String.
     * @return a descriptive <code>String.
     */
    public synchronized String toString() {
        if (isReference()) {
            return getCheckedRef().toString();
        }
        if (coll == null || coll.isEmpty()) {
            return "";
        }
        StringBuffer sb = new StringBuffer();
        for (Iterator i = coll.iterator(); i.hasNext();) {
            if (sb.length() > 0) {
                sb.append(File.pathSeparatorChar);
            }
            sb.append(i.next());
        }
        return sb.toString();
    }

    /**
     * Overrides the version of DataType to recurse on all DataType
     * child elements that may have been added.
     * @param stk the stack of data types to use (recursively).
     * @param p   the project to use to dereference the references.
     * @throws BuildException on error.
     */
    protected void dieOnCircularReference(Stack stk, Project p)
        throws BuildException {
        if (isChecked()) {
            return;
        }
        if (isReference()) {
            super.dieOnCircularReference(stk, p);
        } else {
            for (Iterator i = getNested().iterator(); i.hasNext();) {
                Object o = i.next();
                if (o instanceof DataType) {
                    invokeCircularReferenceCheck((DataType) o, stk, p);
                }
            }
            setChecked(true);
        }
    }

    /**
     * Resolves references, allowing any ResourceCollection.
     * @return the referenced ResourceCollection.
     */
    private ResourceCollection getRef() {
        return (ResourceCollection) getCheckedRef(
            ResourceCollection.class, "ResourceCollection");
    }

    private synchronized void validate() {
        dieOnCircularReference();
        coll = (coll == null) ? new MyCollection() : coll;
    }

    private synchronized List getNested() {
        return rc == null ? Collections.EMPTY_LIST : rc;
    }
}