StringGenerator.java

package com.connsec.util;

import java.lang.management.ManagementFactory;
import java.security.SecureRandom;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.UUID;

import com.connsec.crypto.Base64Utils;

public class StringGenerator {

	private static final int MAX_PID            = 65536;
	
	private  char[] DEFAULT_CODEC = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();
	
	public static final char[] DEFAULT_CODE_NUMBER = "1234567890".toCharArray();
	
	public static final char[] DEFAULT_CODE_LOWERCASE = "abcdefghijklmnopqrstuvwxyz".toCharArray();
	
	public static final char[] DEFAULT_CODE_UPPERCASE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray();
	
	public static final char[] DEFAULT_CODE_LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();
	
	public static final char[] DEFAULT_CODE_NUMBER_LETTERS = "1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz".toCharArray();

	public static int processId;

	private static final String uuidRegex =  "^[0-9a-z]{8}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{4}-[0-9a-z]{12}$";

	
	private Random random = new SecureRandom();

	private int length;
	
	static {
		 final String jvmName = ManagementFactory.getRuntimeMXBean().getName();
		 int index = jvmName.indexOf('@');
        if (index < 1)
            throw new RuntimeException("Could not get PID");

        try {
        	processId= Integer.parseInt(jvmName.substring(0, index)) % MAX_PID;
        } catch (NumberFormatException e) {
            throw new RuntimeException("Could not get PID");
        }
	}

	/**
	 * Create a generator with the default length (6).
	 */
	public StringGenerator() {
		this(6);
	}

	/**
	 * Create a generator of random strings of the length provided
	 * 
	 * @param length the length of the strings generated
	 */
	public StringGenerator(int length) {
		this.length = length;
	}

	public StringGenerator(char[] defaultCode,int length) {
		this.DEFAULT_CODEC=defaultCode;
		this.length = length;
	}
	
	public  String randomGenerate() {
		byte[] verifierBytes = new byte[length];
		random.nextBytes(verifierBytes);
		return getString(verifierBytes);
	}
	
	public  String uuidGenerate() {
		return UUID.randomUUID().toString().toLowerCase();
	}
	
	public  String uniqueGenerate() {
		 StringBuffer uniqueString=new StringBuffer("");

		 this.length=9;
		 String randomString =randomGenerate();
		 uniqueString.append(randomString.subSequence(0, 4));
		 
		 Date currentDate=new Date();
		 DateFormat dateFormat = new SimpleDateFormat("ddMMyyyyHHmmssSSS");
		 String dateString=Base64Utils.encodeBase64(dateFormat.format(currentDate).getBytes());
		 dateString=dateString.substring(0, dateString.length()-1);
		 uniqueString.append(dateString);
		 
		 uniqueString.append(randomString.subSequence(5, 8));
		 
		 return uniqueString.toString();
	}

	/**
	 * Convert these random bytes to a verifier string. The length of the byte array can be
	 * {@link #setLength(int) configured}. The default implementation mods the bytes to fit into the
	 * ASCII letters 1-9, A-Z, a-z .
	 * 
	 * @param verifierBytes The bytes.
	 * @return The string.
	 */
	protected String getString(byte[] verifierBytes) {
		char[] chars = new char[verifierBytes.length];
		for (int i = 0; i < verifierBytes.length; i++) {
			chars[i] = DEFAULT_CODEC[((verifierBytes[i] & 0xFF) % DEFAULT_CODEC.length)];
		}
		return new String(chars);
	}

	/**
	 * The random value generator used to create token secrets.
	 * 
	 * @param random The random value generator used to create token secrets.
	 */
	public void setRandom(Random random) {
		this.random = random;
	}
	
	/**
	 * The length of string to generate.
	 * 
	 * @param length the length to set
	 */
	public void setLength(int length) {
		this.length = length;
	}
	
	
	public static boolean uuidMatches(String uuidString) {
		return uuidString.matches(uuidRegex);
	}
	
}