随机字符串

apai — Wed, 30 May 2007 03:09:00 GMT

package zyz.app;

import java.util.Random;

public class RandomString {
    public static final int LOWER = 0;
    public static final int UPPER = 1;
    public static final int INITIAL = 2;
    public static final int MIX = 3;

    private static final Random random = new Random();

    public String randomString(int len, int type) {
        switch (type) {
        case INITIAL:
            return len < 1 ? internalRandomString(1, UPPER) : internalRandomString(1, UPPER)
                    + internalRandomString(len - 1, LOWER);
        case MIX:
            return internalRandomMixString(len);
        default:
            return internalRandomString(len, type);
        }
    }

    private String internalRandomString(int len, int type) {
        char a;
        switch (type) {
        case UPPER:
            a = 'A';
            break;
        default:
            a = 'a';
        }

        char[] cc = new char[len];
        for (int i = 0; i < len; i++) {
            cc[i] = (char) (random.nextInt(26) + a);
        }

        return new String(cc);
    }

    private String internalRandomMixString(int len) {
        char[] cc = new char[len];
        for (int i = 0; i < len; i++) {
            cc[i] = internalRandomChar(new Random().nextInt(2));
        }

        return new String(cc);
    }

    private char internalRandomChar(int type) {
        char a;
        switch (type) {
        case UPPER:
            a = 'A';
            break;
        default:
            a = 'a';
        }

        return (char) (random.nextInt(26) + a);
    }

    public static void main(String[] args) {
        RandomString rs = new RandomString();

        // test
        for (int i = 0; i < 10; i++) {
            int type = new Random().nextInt(4);
            System.out.println("type:" + type + ",string:" + rs.randomString(20, type));
        }

        // performance test
        long a = System.currentTimeMillis();
        rs.randomString(100000, RandomString.LOWER);
        long b = System.currentTimeMillis();
        rs.randomString(100000, RandomString.MIX);
        long c = System.currentTimeMillis();
        System.out.println("-----------------------------------");
        System.out.println("randomString(100000,lower) = " + (b - a) + "ms");
        System.out.println("randomString(100000,mix) = " + (c - b) + "ms");

    }

}

apai 2007-05-30 11:09 发表评论

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随机字符串