package cn.edu.tyut.scholarship.util;

import java.util.Random;

public class RandomUtils {
	public static final String allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

	public static final String letterChar = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

	public static final String numberChar = "0123456789";

	public static String generateMixString(int length) 
	{

		StringBuffer sb = new StringBuffer();
		
		Random random = new Random();
		
		for (int i = 0; i < length; i++) {
		
		sb.append(allChar.charAt(random.nextInt(letterChar.length())));
		
		}
		
		return sb.toString();	

	}

	public static String generateNumberString(int length) 
	{

		StringBuffer sb = new StringBuffer();
		
		Random random = new Random();
		
		for (int i = 0; i < length; i++) {
		
		sb.append(numberChar.charAt(random.nextInt(numberChar.length())));
		
		}
		
		return sb.toString();	

	}
	public static String generateUpperString(int length) {

		return generateMixString(length).toUpperCase();

	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("generateMixString(6)");
		for (int i=0 ;i<10;i++)
		{
		System.out.println(generateUpperString(6));
		}
		
		System.out.println("generateNumberString(6)");
		for (int i=0 ;i<10;i++)
		{
		System.out.println(generateNumberString(6));
		}		


	}

}