随机数

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web3之路 2019-01-11 14:12:00

文章标签 字符串 i++ 字符串长度随机字符串大小写 文章分类 Java 后端开发

package com.opslab.util;

import java.util.*;

public final class RandomUtil {
public static final String ALLCHAR
= "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String LETTERCHAR
= "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
public static final String NUMBERCHAR
= "0123456789";

/**
* 生成制定范围内的随机数
*
* @param scopeMin
* @param scoeMax
* @return
*/
public static int integer(int scopeMin, int scoeMax) {
Random random = new Random();
return (random.nextInt(scoeMax) % (scoeMax - scopeMin + 1) + scopeMin);
}

/**
* 返回固定长度的数字
*
* @param length
* @return
*/
public static String number(int length) {
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
sb.append(NUMBERCHAR.charAt(random.nextInt(NUMBERCHAR.length())));
}
return sb.toString();
}

/**
* 返回一个定长的随机字符串(只包含大小写字母、数字)
*
* @param length 随机字符串长度
* @return 随机字符串
*/
public static String String(int length) {
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
sb.append(ALLCHAR.charAt(random.nextInt(ALLCHAR.length())));
}
return sb.toString();
}

/**
* 返回一个定长的随机纯字母字符串(只包含大小写字母)
*
* @param length 随机字符串长度
* @return 随机字符串
*/
public static String MixString(int length) {
StringBuffer sb = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
sb.append(ALLCHAR.charAt(random.nextInt(LETTERCHAR.length())));
}
return sb.toString();
}

/**
* 返回一个定长的随机纯大写字母字符串(只包含大小写字母)
*
* @param length 随机字符串长度
* @return 随机字符串
*/
public static String LowerString(int length) {
return MixString(length).toLowerCase();
}

/**
* 返回一个定长的随机纯小写字母字符串(只包含大小写字母)
*
* @param length 随机字符串长度
* @return 随机字符串
*/
public static String UpperString(int length) {
return MixString(length).toUpperCase();
}

/**
* 生成一个定长的纯0字符串
*
* @param length 字符串长度
* @return 纯0字符串
*/
public static String ZeroString(int length) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < length; i++) {
sb.append('0');
}
return sb.toString();
}

/**
* 根据数字生成一个定长的字符串，长度不够前面补0
*
* @param num 数字
* @param fixdlenth 字符串长度
* @return 定长的字符串
*/
public static String toFixdLengthString(long num, int fixdlenth) {
StringBuffer sb = new StringBuffer();
String strNum = String.valueOf(num);
if (fixdlenth - strNum.length() >= 0) {
sb.append(ZeroString(fixdlenth - strNum.length()));
} else {
throw new RuntimeException("将数字" +
num + "转化为长度为" + fixdlenth + "的字符串发生异常！");
}
sb.append(strNum);
return sb.toString();
}

/**
* 根据数字生成一个定长的字符串，长度不够前面补0
*
* @param num 数字
* @param fixdlenth 字符串长度
* @return 定长的字符串
*/
public static String toFixdLengthString(int num, int fixdlenth) {
StringBuffer sb = new StringBuffer();
String strNum = String.valueOf(num);
if (fixdlenth - strNum.length() >= 0) {
sb.append(ZeroString(fixdlenth - strNum.length()));
} else {
throw new RuntimeException("将数字" +
num + "转化为长度为" + fixdlenth + "的字符串发生异常！");
}
sb.append(strNum);
return sb.toString();
}

/**
* 每次生成的len位数都不相同
*
* @param param
* @return 定长的数字
*/
public static int getNotSimple(int[] param, int len) {
Random rand = new Random();
for (int i = param.length; i > 1; i--) {
int index = rand.nextInt(i);
int tmp = param[index];
param[index] = param[i - 1];
param[i - 1] = tmp;
}
int result = 0;
for (int i = 0; i < len; i++) {
result = result * 10 + param[i];
}
return result;
}

/**
* 从指定的数组中随机数组中的某个元素
*/
public static <T> T randomItem(T[] param) {
int index = integer(0, param.length);
return param[index];
}

/**
* 实现一个简单的字符串乘法
* @param str
* @param multiplication
* @return
*/
private static String strMultiplication(String str,int multiplication){
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < multiplication; i++) {
buffer.append(str);
}
return buffer.toString();
}
/**
* 从指定的数组中按照指定比例返回指定的随机元素
* @param param
* @param percentum
* @param <T>
* @return
*/
public static <T> T randomItem(T[] param,double[] percentum){
int length = percentum.length;
Integer[] ints = ArrayUtil.doubleBitCount(percentum);
int max = Collections.max(Arrays.asList(ints));
int[] arr = new int[length];
int sum = 0;
Map map = new HashMap(length);
int multiple = Integer.parseInt("1"+strMultiplication("0",max));
for (int i = 0; i < length; i++) {
int temp = (int)(percentum[i] * multiple);
arr[i] = temp;
if(i == 0){
map.put(i,new int[]{1,temp});
}else{
map.put(i,new int[]{sum,sum+temp});
}
sum += temp;
}
int indexSum = integer(1,sum);
int index =-1;
for (int i = 0; i < length; i++) {
int[] scope = (int[]) map.get(i);
if(indexSum ==1 ){
index = 0;
break;
}
if(indexSum > scope[0] && indexSum <= scope[1]){
index =i;
break;
}
}
if(index == -1){
throw new RuntimeException("随机失败");
}else{
return param[index];
}
}
/**
* 返回一个UUID
*
* @return 小写的UUID
*/
public static String uuid() {
UUID uuid = UUID.randomUUID();
String s = uuid.toString();
return s.substring(0, 8) + s.substring(9, 13) +
s.substring(14, 18) + s.substring(19, 23) + s.substring(24);
}

/**
* 返回一个UUID
*
* @return 大写的UUID
*/
public static String UUID() {
UUID uuid = UUID.randomUUID();
String s = uuid.toString();
String temp = s.substring(0, 8) + s.substring(9, 13) +
s.substring(14, 18) + s.substring(19, 23) + s.substring(24);
return temp.toUpperCase();
}

/**
* 返回一个有序列的uuid编码
* 前11位为时间(毫秒)
* 中间4位为主机特征码
* 剩下的保证其唯一性
*
* @return
*/
public static String squid() {
Long date = new Date().getTime();
String s = UUID.randomUUID().toString();
String str = Long.toHexString(date);
String result = str + OpslabConfig.HOST_FEATURE
+ s.substring(17, 18) + s.substring(19, 23) + s.substring(24);
return result.toUpperCase();
}
}