import java.util.Random;

public class RandomUtils {

    public static String generateKey(int length) {
        String alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        int n = alphabet.length();

        StringBuffer result = new StringBuffer();
        Random r = new Random();
        for (int i = 0; i < length; i++) {
            result.append(alphabet.charAt(r.nextInt(n)));
        }
        return result.toString();
    }

    /**
     * 随机生成N位数字串
     * 
     * @param length
     * @return
     */
    public static String generateDigits(int length) {
        String alphabet = "0123456789";
        int n = alphabet.length();

        StringBuffer result = new StringBuffer();
        Random r = new Random();
        for (int i = 0; i < length; i++) {
            result.append(alphabet.charAt(r.nextInt(n)));
        }
        return result.toString();
    }

}