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Ant example source code file (JavaResource.java)

This example Ant source code file (JavaResource.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

classloader, classloader, comparable, inputstream, io, ioexception, javaresource, javaresource, path, path, reference, resource, resource

The JavaResource.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.IOException;
import java.io.InputStream;

import org.apache.tools.ant.util.FileUtils;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.Reference;

/**
 * A Resource representation of something loadable via a Java classloader.
 * @since Ant 1.7
 */
public class JavaResource extends Resource {

    private Path classpath;
    private Reference loader;

    /**
     * Default constructor.
     */
    public JavaResource() {
    }

    /**
     * Construct a new JavaResource using the specified name and
     * classpath.
     *
     * @param name   the resource name.
     * @param path   the classpath.
     */
    public JavaResource(String name, Path path) {
        setName(name);
        classpath = path;
    }

    /**
     * Set the classpath to use when looking up a resource.
     * @param classpath to add to any existing classpath
     */
    public void setClasspath(Path classpath) {
        checkAttributesAllowed();
        if (this.classpath == null) {
            this.classpath = classpath;
        } else {
            this.classpath.append(classpath);
        }
    }

    /**
     * Add a classpath to use when looking up a resource.
     * @return The classpath to be configured
     */
    public Path createClasspath() {
        checkChildrenAllowed();
        if (this.classpath == null) {
            this.classpath = new Path(getProject());
        }
        return this.classpath.createPath();
    }

    /**
     * Set the classpath to use when looking up a resource,
     * given as reference to a <path> defined elsewhere
     * @param r The reference value
     */
    public void setClasspathRef(Reference r) {
        checkAttributesAllowed();
        createClasspath().setRefid(r);
    }

    /**
     * get the classpath used by this <code>LoadProperties.
     * @return The classpath
     */
    public Path getClasspath() {
        return isReference()
            ? ((JavaResource) getCheckedRef()).getClasspath() : classpath;
    }

    /**
     * Use the reference to locate the loader. If the loader is not
     * found, taskdef will use the specified classpath and register it
     * with the specified name.
     *
     * This allow multiple taskdef/typedef to use the same class loader,
     * so they can be used together. It eliminate the need to
     * put them in the CLASSPATH.
     *
     * @param r the reference to locate the loader.
     */
    public void setLoaderRef(Reference r) {
        checkAttributesAllowed();
        loader = r;
    }

    /**
     * Overrides the super version.
     * @param r the Reference to set.
     */
    public void setRefid(Reference r) {
        if (loader != null || classpath != null) {
            throw tooManyAttributes();
        }
        super.setRefid(r);
    }

    /**
     * Learn whether this file exists.
     * @return true if this resource exists.
     */
    public boolean isExists() {
        InputStream is = null;
        try {
            return isReference() ? ((Resource) getCheckedRef()).isExists()
                : (is = getInputStream()) != null;
        } catch (IOException ex) {
            return false;
        } finally {
            FileUtils.close(is);
        }
    }

    /**
     * Return an InputStream for reading the contents of this Resource.
     * @return an InputStream object.
     * @throws IOException if an error occurs.
     */
    public InputStream getInputStream() throws IOException {
        if (isReference()) {
            return ((Resource) getCheckedRef()).getInputStream();
        }
        ClassLoader cl = null;
        if (loader != null) {
            cl = (ClassLoader) loader.getReferencedObject();
        }
        if (cl == null) {
            if (getClasspath() != null) {
                cl = getProject().createClassLoader(classpath);
            } else {
                cl = JavaResource.class.getClassLoader();
            }
            if (loader != null && cl != null) {
                getProject().addReference(loader.getRefId(), cl);
            }
        }

        return cl == null ? ClassLoader.getSystemResourceAsStream(getName())
            : cl.getResourceAsStream(getName());
    }

    /**
     * Compare this JavaResource to another Resource.
     * @param another the other Resource against which to compare.
     * @return a negative integer, zero, or a positive integer as this
     * JavaResource is less than, equal to, or greater than the
     * specified Resource.
     */
    public int compareTo(Object another) {
        if (isReference()) {
            return ((Comparable) getCheckedRef()).compareTo(another);
        }
        if (another.getClass().equals(getClass())) {
            JavaResource otherjr = (JavaResource) another;
            if (!getName().equals(otherjr.getName())) {
                return getName().compareTo(otherjr.getName());
            }
            if (loader != otherjr.loader) {
                if (loader == null) {
                    return -1;
                }
                if (otherjr.loader == null) {
                    return 1;
                }
                return loader.getRefId().compareTo(otherjr.loader.getRefId());
            }
            Path p = getClasspath();
            Path op = otherjr.getClasspath();
            if (p != op) {
                if (p == null) {
                    return -1;
                }
                if (op == null) {
                    return 1;
                }
                return p.toString().compareTo(op.toString());
            }
            return 0;
        }
        return super.compareTo(another);
    }

}

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