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 [java] password generator

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kurosen
codding
codding
kurosen

Posts : 293
Join date : 2012-04-17

[java] password generator Empty
PostSubject: [java] password generator   [java] password generator EmptySat Jan 16, 2021 3:34 pm

Code:
package chobit;



import java.util.ArrayList;

import java.util.List;

import java.util.Random;



public final class PasswordGenerator {



    private static final String LOWER = "abcdefghijklmnopqrstuvwxyz";

    private static final String UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    private static final String DIGITS = "0123456789";

    private static final String PUNCTUATION = "!@#$%&*()_+-=[]|,./?><";

    private boolean useLower;

    private boolean useUpper;

    private boolean useDigits;

    private boolean usePunctuation;



    private PasswordGenerator() {

        throw new UnsupportedOperationException("Empty constructor is not supported.");

    }



    private PasswordGenerator(PasswordGeneratorBuilder builder) {

        this.useLower = builder.useLower;

        this.useUpper = builder.useUpper;

        this.useDigits = builder.useDigits;

        this.usePunctuation = builder.usePunctuation;

    }



    public static class PasswordGeneratorBuilder {



        private boolean useLower;

        private boolean useUpper;

        private boolean useDigits;

        private boolean usePunctuation;



        public PasswordGeneratorBuilder() {

            this.useLower = false;

            this.useUpper = false;

            this.useDigits = false;

            this.usePunctuation = false;

        }



        /**

         * Set true in case you would like to include lower characters (abc...xyz).

         * Default false.

         *

         * @param useLower

         *            true in case you would like to include lower characters

         *            (abc...xyz). Default false.

         * @return the builder for chaining.

         */

        public PasswordGeneratorBuilder useLower(boolean useLower) {

            this.useLower = useLower;

            return this;

        }



        /**

         * Set true in case you would like to include upper characters (ABC...XYZ).

         * Default false.

         *

         * @param useUpper

         *            true in case you would like to include upper characters

         *            (ABC...XYZ). Default false.

         * @return the builder for chaining.

         */

        public PasswordGeneratorBuilder useUpper(boolean useUpper) {

            this.useUpper = useUpper;

            return this;

        }



        /**

         * Set true in case you would like to include digit characters (123..). Default

         * false.

         *

         * @param useDigits

         *            true in case you would like to include digit characters (123..).

         *            Default false.

         * @return the builder for chaining.

         */

        public PasswordGeneratorBuilder useDigits(boolean useDigits) {

            this.useDigits = useDigits;

            return this;

        }



        /**

         * Set true in case you would like to include punctuation characters (!@#..).

         * Default false.

         *

         * @param usePunctuation

         *            true in case you would like to include punctuation characters

         *            (!@#..). Default false.

         * @return the builder for chaining.

         */

        public PasswordGeneratorBuilder usePunctuation(boolean usePunctuation) {

            this.usePunctuation = usePunctuation;

            return this;

        }



        /**

         * Get an object to use.

         *

         * @return the {@link gr.idrymavmela.business.lib.PasswordGenerator} object.

         */

        public PasswordGenerator build() {

            return new PasswordGenerator(this);

        }

    }



    /**

     * This method will generate a password depending the use* properties you

     * define. It will use the categories with a probability. It is not sure that

     * all of the defined categories will be used.

     *

     * @param length

     *            the length of the password you would like to generate.

     * @return a password that uses the categories you define when constructing the

     *         object with a probability.

     */

    public String generate(int length) {

        // Argument Validation.

        if (length <= 0) {

            return "";

        }



        // Variables.

        StringBuilder password = new StringBuilder(length);

        Random random = new Random(System.nanoTime());



        // Collect the categories to use.

        List<String> charCategories = new ArrayList<>(4);

        if (useLower) {

            charCategories.add(LOWER);

        }

        if (useUpper) {

            charCategories.add(UPPER);

        }

        if (useDigits) {

            charCategories.add(DIGITS);

        }

        if (usePunctuation) {

            charCategories.add(PUNCTUATION);

        }



        // Build the password.

        for (int i = 0; i < length; i++) {

            String charCategory = charCategories.get(random.nextInt(charCategories.size()));

            int position = random.nextInt(charCategory.length());

            password.append(charCategory.charAt(position));

        }

        return new String(password);

    }

}



use example :



Code:
PasswordGenerator passwordGenerator = new PasswordGenerator.PasswordGeneratorBuilder().useDigits(true)

                .useLower(true).useUpper(true).build();

        String password = passwordGenerator.generate(8);

        System.out.println(password);
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