nio/file/Xdd.java

/*
 * 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
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 * 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>=<value> <file>");
        System.out.println("       java Xdd -get <name> <file>");
        System.out.println("       java Xdd -del <name> <file>");
        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();
    }
 }