「工具」随机数生成
作者:互联网
import java.util.Random;
/**
* @ClassName RandomUtils.java
* @Description 随机数生成
*/
public class RandomUtils {
private static final String SPECIAL_CHARS = "!@#$%^&*_=+-/";
/**
* 查找一个char数组中还没有填充字符的位置
*/
private static int nextIndex(char[] chars, Random rnd) {
int index = rnd.nextInt(chars.length);
while (chars[index] != 0) {
index = rnd.nextInt(chars.length);
}
return index;
}
/**
* 返回一个随机的特殊字符
*/
private static char nextSpecialChar(Random rnd) {
return SPECIAL_CHARS.charAt(rnd.nextInt(SPECIAL_CHARS.length()));
}
/**
* 返回一个随机的大写字母
*/
private static char nextUpperLetter(Random rnd) {
return (char) ('A' + rnd.nextInt(26));
}
/**
* 返回一个随机的小写字母
*/
private static char nextLowerLetter(Random rnd) {
return (char) ('a' + rnd.nextInt(26));
}
/**
* 返回一个随机的数字
*/
private static char nextNumLetter(Random rnd) {
return (char) ('0' + rnd.nextInt(10));
}
/**
* 返回一个随机的字符
*/
private static char nextChar(Random rnd) {
switch (rnd.nextInt(3)) {
case 0:
return (char) ('a' + rnd.nextInt(26));
case 1:
return (char) ('A' + rnd.nextInt(26));
default:
return (char) ('0' + rnd.nextInt(10));
}
}
/**
* 返回一个随机的字符(包含特殊字符)
*/
private static char nextCharWithSpecialChars(Random rnd) {
switch (rnd.nextInt(4)) {
case 0:
return (char) ('a' + rnd.nextInt(26));
case 1:
return (char) ('A' + rnd.nextInt(26));
case 2:
return (char) ('0' + rnd.nextInt(10));
default:
return SPECIAL_CHARS.charAt(rnd.nextInt(SPECIAL_CHARS.length()));
}
}
/**
* 生成指定位数的随机数
* @param length 长度
* @param containSpecialChars 是否包含特殊字符
*/
public static String randomChars(int length, boolean containSpecialChars){
char[] chars = new char[length];
Random rnd = new Random();
//1. 填补空白位置的字符
for (int i = 0; i < length; i++) {
if (chars[i] == 0) {
chars[i] = (containSpecialChars ? nextCharWithSpecialChars(rnd) : nextChar(rnd));
}
}
//2. 返回结果
return new String(chars);
}
/**
* 生成指定位数的随机密码
* @param length 长度
*/
public static String randomPassword(int length) {
if(length < 4){
return "";
}
char[] chars = new char[length];
Random rnd = new Random();
//1. 至少生成一个大写字母、小写字母、特殊字符、数字
chars[nextIndex(chars, rnd)] = nextSpecialChar(rnd);
chars[nextIndex(chars, rnd)] = nextUpperLetter(rnd);
chars[nextIndex(chars, rnd)] = nextLowerLetter(rnd);
chars[nextIndex(chars, rnd)] = nextNumLetter(rnd);
//2. 填补其他位置的字符
for (int i = 0; i < length; i++) {
if (chars[i] == 0) {
chars[i] = nextCharWithSpecialChars(rnd);
}
}
//3. 返回结果
return new String(chars);
}
}
标签:return,chars,rnd,char,nextInt,length,随机数,工具,生成 来源: https://www.cnblogs.com/xfeiyun/p/15770619.html