Java example source code file (Xdd.java)

This example Java source code file (Xdd.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytebuffer, filestore, ioexception, nio, path, string, userdefinedfileattributeview, xdd

The Xdd.java Java example source code

/*
 * Copyright (c) 2008, 2011, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.file.*;
import java.nio.file.attribute.*;
import java.io.IOException;

/**
 * Example code to list/set/get/delete the user-defined attributes of a file.
 */

public class Xdd {

    static void usage() {
        System.out.println("Usage: java Xdd <file>");
        System.out.println("       java Xdd -set <name>= ");
        System.out.println("       java Xdd -get <name> ");
        System.out.println("       java Xdd -del <name> ");
        System.exit(-1);
    }

    public static void main(String[] args) throws IOException {
        // one or three parameters
        if (args.length != 1 && args.length != 3)
            usage();

        Path file = (args.length == 1) ?
            Paths.get(args[0]) : Paths.get(args[2]);

        // check that user defined attributes are supported by the file store
        FileStore store = Files.getFileStore(file);
        if (!store.supportsFileAttributeView(UserDefinedFileAttributeView.class)) {
            System.err.format("UserDefinedFileAttributeView not supported on %s\n", store);
            System.exit(-1);

        }
        UserDefinedFileAttributeView view =
            Files.getFileAttributeView(file, UserDefinedFileAttributeView.class);

        // list user defined attributes
        if (args.length == 1) {
            System.out.println("    Size  Name");
            System.out.println("--------  --------------------------------------");
            for (String name: view.list()) {
                System.out.format("%8d  %s\n", view.size(name), name);
            }
            return;
        }

        // Add/replace a file's user defined attribute
        if (args[0].equals("-set")) {
            // name=value
            String[] s = args[1].split("=");
            if (s.length != 2)
                usage();
            String name = s[0];
            String value = s[1];
            view.write(name, Charset.defaultCharset().encode(value));
            return;
        }

        // Print out the value of a file's user defined attribute
        if (args[0].equals("-get")) {
            String name = args[1];
            int size = view.size(name);
            ByteBuffer buf = ByteBuffer.allocateDirect(size);
            view.read(name, buf);
            buf.flip();
            System.out.println(Charset.defaultCharset().decode(buf).toString());
            return;
        }

        // Delete a file's user defined attribute
        if (args[0].equals("-del")) {
            view.delete(args[1]);
            return;
        }

        // option not recognized
        usage();
    }
 }