Ant example source code file (Pack.java)

This example Ant source code file (Pack.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, fileresource, fileresource, filesystem, io, ioexception, ioexception, nothing, only, outputstream, resource, resource, task

The Pack.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.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.types.ResourceCollection;
import org.apache.tools.ant.types.resources.FileResource;

/**
 * Abstract Base class for pack tasks.
 *
 * @since Ant 1.5
 */

public abstract class Pack extends Task {

    // CheckStyle:VisibilityModifier OFF - bc
    protected File zipFile;
    protected File source;
    // CheckStyle:VisibilityModifier ON
    private Resource src;

    /**
     * the required destination file.
     * @param zipFile the destination file
     */
    public void setZipfile(File zipFile) {
        this.zipFile = zipFile;
    }

    /**
     * the required destination file.
     * @param zipFile the destination file
     */
    public void setDestfile(File zipFile) {
        setZipfile(zipFile);
    }

    /**
     * the file to compress; required.
     * @param src the source file
     */
    public void setSrc(File src) {
        setSrcResource(new FileResource(src));
    }

    /**
     * The resource to pack; required.
     * @param src resource to expand
     */
    public void setSrcResource(Resource src) {
        if (src.isDirectory()) {
            throw new BuildException("the source can't be a directory");
        }
        if (src instanceof FileResource) {
            source = ((FileResource) src).getFile();
        } else if (!supportsNonFileResources()) {
            throw new BuildException("Only FileSystem resources are"
                                     + " supported.");
        }
        this.src = src;
    }

    /**
     * Set the source resource.
     * @param a the resource to pack as a single element Resource collection.
     */
    public void addConfigured(ResourceCollection a) {
        if (a.size() != 1) {
            throw new BuildException("only single argument resource collections"
                                     + " are supported as archives");
        }
        setSrcResource((Resource) a.iterator().next());
    }

    /**
     * validation routine
     * @throws BuildException if anything is invalid
     */
    private void validate() throws BuildException {
        if (zipFile == null) {
            throw new BuildException("zipfile attribute is required", getLocation());
        }

        if (zipFile.isDirectory()) {
            throw new BuildException("zipfile attribute must not "
                                    + "represent a directory!", getLocation());
        }

        if (getSrcResource() == null) {
            throw new BuildException("src attribute or nested resource is"
                                     + " required", getLocation());
        }
    }

    /**
     * validate, then hand off to the subclass
     * @throws BuildException on error
     */
    public void execute() throws BuildException {
        validate();

        Resource s = getSrcResource();
        if (!s.isExists()) {
            log("Nothing to do: " + s.toString()
                + " doesn't exist.");
        } else if (zipFile.lastModified() < s.getLastModified()) {
            log("Building: " + zipFile.getAbsolutePath());
            pack();
        } else {
            log("Nothing to do: " + zipFile.getAbsolutePath()
                + " is up to date.");
        }
    }

    /**
     * zip a stream to an output stream
     * @param in   the stream to zip
     * @param zOut the output stream
     * @throws IOException
     */
    private void zipFile(InputStream in, OutputStream zOut)
        throws IOException {
        byte[] buffer = new byte[8 * 1024];
        int count = 0;
        do {
            zOut.write(buffer, 0, count);
            count = in.read(buffer, 0, buffer.length);
        } while (count != -1);
    }

    /**
     * zip a file to an output stream
     * @param file the file to zip
     * @param zOut the output stream
     * @throws IOException on error
     */
    protected void zipFile(File file, OutputStream zOut)
        throws IOException {
        zipResource(new FileResource(file), zOut);
    }

    /**
     * zip a resource to an output stream
     * @param resource the resource to zip
     * @param zOut the output stream
     * @throws IOException on error
     */
    protected void zipResource(Resource resource, OutputStream zOut)
        throws IOException {
        InputStream rIn = resource.getInputStream();
        try {
            zipFile(rIn, zOut);
        } finally {
            rIn.close();
        }
    }

    /**
     * subclasses must implement this method to do their compression
     */
    protected abstract void pack();

    /**
     * The source resource.
     * @return the source.
     * @since Ant 1.7
     */
    public Resource getSrcResource() {
        return src;
    }

    /**
     * Whether this task can deal with non-file resources.
     *
     * <p>This implementation returns false.

     * @return false.
     * @since Ant 1.7
     */
    protected boolean supportsNonFileResources() {
        return false;
    }
}