java生产指定长度随机字符串a-z,A-Z,0-9

import java.util.Random;
import java.util.UUID;

/**
 * 制造指定长度随机字符串a-z,A-Z,0-9
 * @author happyqing
 * @since 2016.5.30
 */
public class RandomString {

	/**
	 * 获得随机字符串 a-z,A-Z,0-9
	 * 
	 * @param length
	 *            长度
	 * @return
	 */
	public static String getRandomString(int length) {
		String str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		Random random = new Random();
		StringBuffer sb = new StringBuffer();

		for (int i = 0; i < length; ++i) {
			int number = random.nextInt(62);// [0,62)
			sb.append(str.charAt(number));
		}
		return sb.toString();
	}

	/**
	 * JAVA取得0-9,a-z,A-Z规模的随机数
	 * 
	 * @param length
	 *            随机数长度
	 * @return String
	 */
	public static String getRandomChar(int length) {
		char[] chr = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", 
				"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", 
				"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z" };
		Random random = new Random();
		StringBuffer buffer = new StringBuffer();
		for (int i = 0; i < length; i++) {
			buffer.append(chr[random.nextInt(62)]);
		}
		return buffer.toString();
	}

	public static void main(String[] args) {
		System.out.println(getRandomString(32));
		System.out.println(getRandomChar(32));
		//UUID
		String uuid = UUID.randomUUID().toString().replaceAll("-", "");
		System.out.println(uuid);
	}
}import java.util.Random;
import java.util.UUID;