Ant example source code file (JarLibAvailableTask.java)

This example Ant source code file (JarLibAvailableTask.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, can, extension, extension, extensionadapter, extensionset, file, file, io, jar, jarlibavailabletask, string, string, task, util, vector

The JarLibAvailableTask.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.optional.extension;

import java.io.File;
import java.util.Iterator;
import java.util.Vector;
import java.util.jar.Manifest;
import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.Task;

/**
 * Checks whether an extension is present in a fileset or an extensionSet.
 *
 * @ant.task name="jarlib-available"
 */
public class JarLibAvailableTask extends Task {
    /**
     * The library to display information about.
     */
    private File libraryFile;

    /**
     * Filesets specifying all the librarys
     * to display information about.
     */
    private final Vector extensionFileSets = new Vector();

    /**
     * The name of the property to set if extension is available.
     */
    private String propertyName;

    /**
     * The extension that is required.
     */
    private ExtensionAdapter requiredExtension;

    /**
     * The name of property to set if extensions are available.
     *
     * @param property The name of property to set if extensions is available.
     */
    public void setProperty(final String property) {
        this.propertyName = property;
    }

    /**
     * The JAR library to check.
     *
     * @param file The jar library to check.
     */
    public void setFile(final File file) {
        this.libraryFile = file;
    }

    /**
     * Set the Extension looking for.
     *
     * @param extension Set the Extension looking for.
     */
    public void addConfiguredExtension(final ExtensionAdapter extension) {
        if (null != requiredExtension) {
            final String message = "Can not specify extension to "
                + "search for multiple times.";
            throw new BuildException(message);
        }
        requiredExtension = extension;
    }

    /**
     * Adds a set of extensions to search in.
     *
     * @param extensionSet a set of extensions to search in.
     */
    public void addConfiguredExtensionSet(final ExtensionSet extensionSet) {
        extensionFileSets.addElement(extensionSet);
    }

    /**
     * Execute the task.
     *
     * @throws BuildException if somethign goes wrong.
     */
    public void execute() throws BuildException {
        validate();

        final Extension test = requiredExtension.toExtension();

        // Check if list of files to check has been specified
        if (!extensionFileSets.isEmpty()) {
            final Iterator iterator = extensionFileSets.iterator();
            while (iterator.hasNext()) {
                final ExtensionSet extensionSet
                    = (ExtensionSet) iterator.next();
                final Extension[] extensions =
                    extensionSet.toExtensions(getProject());
                for (int i = 0; i < extensions.length; i++) {
                    final Extension extension = extensions[ i ];
                    if (extension.isCompatibleWith(test)) {
                        getProject().setNewProperty(propertyName, "true");
                    }
                }
            }
        } else {
            final Manifest manifest = ExtensionUtil.getManifest(libraryFile);
            final Extension[] extensions = Extension.getAvailable(manifest);
            for (int i = 0; i < extensions.length; i++) {
                final Extension extension = extensions[ i ];
                if (extension.isCompatibleWith(test)) {
                    getProject().setNewProperty(propertyName, "true");
                }
            }
        }
    }

    /**
     * Validate the tasks parameters.
     *
     * @throws BuildException if invalid parameters found
     */
    private void validate() throws BuildException {
        if (null == requiredExtension) {
            final String message = "Extension element must be specified.";
            throw new BuildException(message);
        }

        if (null == libraryFile && extensionFileSets.isEmpty()) {
            final String message = "File attribute not specified.";
            throw new BuildException(message);
        }
        if (null != libraryFile && !libraryFile.exists()) {
            final String message = "File '" + libraryFile + "' does not exist.";
            throw new BuildException(message);
        }
        if (null != libraryFile && !libraryFile.isFile()) {
            final String message = "\'" + libraryFile + "\' is not a file.";
            throw new BuildException(message);
        }
    }
}