java 生成随机数

ackage com.test.util;
public class RandomUtil {
/**
* 返回一个0-count（包含count）的随机数
* @param count
* @return
*/
public int getRandom(int count) {
        return (int) Math.round(Math.random() * (count));
    }
private String string = "0123456789abcdefghijklmnopqrstuvwxyz";
/**
* 从0123456789abcdefghijklmnopqrstuvwxyz中选随机生成长度为length的字符串
* @param length
* @return
*/
public String getRandomString(int length){
StringBuffer sb = new StringBuffer();
int len = string.length();
for (int i = 0; i < length; i++) {
sb.append(string.charAt(this.getRandom(len-1)));
}
return sb.toString();
}
public static void main(String[] args) {
RandomUtil ru = new RandomUtil();
for (int i = 0; i < 10; i++) {
Log.logInfo(ru.getRandomString(6));
//System.out.println(ru.getRandomString(8));
}
}  
}