Java 如何获取随机字符串、随机数

java获取随机字符串 、随机数

/**
* 随机字符串
*
* @author TangRen
* @param length
* @return
* @time 2016-7-7
*/
public static String Random(int length) {
char[] str= new char[length];
int i = 0;
int num=3;//数字的个数
while (i < length) {
int f = (int) (Math.random() * num);
if (f == 0)
str[i] = (char) ('A' + Math.random() * 26);
else if (f == 1)
str[i] = (char) ('a' + Math.random() * 26);
else
str[i] = (char) ('0' + Math.random() * 10);
i++;
}
String random_str = new String(str);
return random_str;
}

/**
* 随机数
*
* @author TangRen
* @param length
* @return
* @time 2016-7-7
*/
public static int buildRandom(int length) {
int num = 1;
double random = Math.random();
if (random < 0.1) {
random = random + 0.1;
}
for (int i = 0; i < length; i++) {
num = num * 10;
}
return (int) ((random * num));
}