| /* |
| * Copyright (c) 2014, 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.security.SecureRandom; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.stream.IntStream; |
| |
| /** |
| * Generates password of desired length. See {@link #usage} method |
| * for instructions and command line parameters. This sample shows usages of: |
| * <ul> |
| * <li>Method references.</li> |
| * <li>Lambda and bulk operations. A stream of random integers is mapped to |
| * chars, limited by desired length and printed in standard output as password |
| * string.</li> |
| * </ul> |
| * |
| */ |
| public class PasswordGenerator { |
| |
| private static void usage() { |
| System.out.println("Usage: PasswordGenerator LENGTH"); |
| System.out.println( |
| "Password Generator produces password of desired LENGTH."); |
| } |
| |
| private static final List<Integer> PASSWORD_CHARS = new ArrayList<>(); |
| |
| //Valid symbols. |
| static { |
| IntStream.rangeClosed('0', '9').forEach(PASSWORD_CHARS::add); // 0-9 |
| IntStream.rangeClosed('A', 'Z').forEach(PASSWORD_CHARS::add); // A-Z |
| IntStream.rangeClosed('a', 'z').forEach(PASSWORD_CHARS::add); // a-z |
| } |
| |
| /** |
| * The main method for the PasswordGenerator program. Run program with empty |
| * argument list to see possible arguments. |
| * |
| * @param args the argument list for PasswordGenerator. |
| */ |
| public static void main(String[] args) { |
| |
| if (args.length != 1) { |
| usage(); |
| return; |
| } |
| |
| long passwordLength; |
| try { |
| passwordLength = Long.parseLong(args[0]); |
| if (passwordLength < 1) { |
| printMessageAndUsage("Length has to be positive"); |
| return; |
| } |
| } catch (NumberFormatException ex) { |
| printMessageAndUsage("Unexpected number format" + args[0]); |
| return; |
| } |
| /* |
| * Stream of random integers is created containing Integer values |
| * in range from 0 to PASSWORD_CHARS.size(). |
| * The stream is limited by passwordLength. |
| * Valid chars are selected by generated index. |
| */ |
| new SecureRandom().ints(passwordLength, 0, PASSWORD_CHARS.size()) |
| .map(PASSWORD_CHARS::get) |
| .forEach(i -> System.out.print((char) i)); |
| } |
| |
| private static void printMessageAndUsage(String message) { |
| System.err.println(message); |
| usage(); |
| } |
| |
| } |