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Sample applications to demonstrate the usage of various TrueZIP module APIs. Some of these samples use rather advanced or exotic features which makes them more complex than necessary for a typical application. By design, the sample applications use all file system drivers which can be located at runtime. Location of the available file system drivers is performed by scanning the class path - see the Javaodoc for the TrueZIP Kernel class de.schlichtherle.truezip.fs.sl.FsDriverLocator for more information.

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/*
 * Copyright (C) 2007-2011 Schlichtherle IT Services
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package de.schlichtherle.truezip.sample.file.app;

import de.schlichtherle.truezip.key.pbe.swing.HurlingWindowFeedback;
import de.schlichtherle.truezip.key.pbe.swing.InvalidKeyFeedback;
import de.schlichtherle.truezip.file.TApplication;
import edu.umd.cs.findbugs.annotations.DefaultAnnotation;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.io.OutputStream;
import java.io.PrintStream;

/**
 * Abstract base class for command line utilities.
 *
 * @author  Christian Schlichtherle
 * @version $Id$
 */
@DefaultAnnotation(NonNull.class)
abstract class Application extends TApplication {

    /** The print stream for standard output. */
    protected final PrintStream out;

    /** The print stream for error output. */
    protected final PrintStream err;

    /**
     * Equivalent to
     * {@link #Application(OutputStream, OutputStream, boolean)
     * Application(System.out, System.err, true)}.
     */
    protected Application() {
        this(System.out, System.err, true);
    }

    /**
     * Constructs a new command line utility instance.
     *
     * @param out the standard output stream.
     * @param err the error output stream.
     * @param autoFlush if the output streams are not {@link PrintStream}s,
     *        then they are wrapped in a new {@code PrintStream} with
     *        this value as the additional constructor parameter.
     */
    protected Application(
            final @Nullable OutputStream out,
            final @Nullable OutputStream err,
            final boolean autoFlush) {
        this.out = out instanceof PrintStream
                ? (PrintStream) out
                : new PrintStream(out, autoFlush);
        this.err = err instanceof PrintStream
                ? (PrintStream) err
                : new PrintStream(err, autoFlush);
    }

    /**
     * Configures the type of the feedback when prompting the user for keys
     * for RAES encrypted ZIP alias ZIP.RAES alias TZP files by the Swing
     * based prompting key manager.
     * If this JVM is running in headless mode, then this configuration is
     * ignored and the user is prompted by the console I/O based prompting
     * key manager.
     */
    @Override
    protected void setup() {
        String spec = InvalidKeyFeedback.class.getName();
        String impl = HurlingWindowFeedback.class.getName();
        System.setProperty(spec, System.getProperty(spec, impl));
    }

    /**
     * Runs the work phase by calling {@link #runChecked}.
     * Prints a user readable error message to the error output stream
     * which was provided to the constructor if an {@link Exception occurs}.
     * 
     * This method is {@link #run run} at least once and repeatedly called
     * until {@link #runChecked} returns a non-negative integer for use as the
     * {@link System#exit(int) exist status} of the VM.
     * After this method, the {@link #sync} method is called in a
     * finally-block.
     * 
     * @param  args an array of arguments for this command line utility.
     * @return A negative integer in order to continue calling this method
     *         in a loop.
     *         Otherwise, the return value is used as the
     *         {@link System#exit(int) exit status} of the VM.
     * @throws RuntimeException at the discretion of {@link #runChecked}.
     */
    @Override
    protected final int work(final String[] args) {
        try {
            return runChecked(args);
        } catch (IllegalUsageException ex) {
            err.println(ex.getLocalizedMessage());
            return 1;
        } catch (Exception ex) {
            ex.printStackTrace(err);
            return 1;
        }
    }

    /**
     * Runs this command line utility.
     * Throws an exception if an error occurs.
     * 
     * Avoid repeating this method and updating the same archive file upon
     * each call!
     * This would degrade the overall performance from O(n) to O(m*n),
     * where m is the number of new or modified entries and n is the number
     * of all entries in the archive file!
     *
     * @param  args an array of arguments for this command line utility.
     * @return A negative integer in order to continue calling this method
     *         in a loop.
     *         Otherwise, the return value is used as the
     *         {@link System#exit(int) exit status} of the VM.
     * @throws Exception on any exception.
     */
    protected abstract int runChecked(String[] args) throws Exception;

    /** Indicates illegal application parameters. */
    @SuppressWarnings("PackageVisibleInnerClass")
    protected static class IllegalUsageException extends Exception {
        private static final long serialVersionUID = 1985623981423542464L;

        protected IllegalUsageException(String msg) {
            super(msg);
        }
    } // IllegalUsageException
}