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工作中需要生成随机String,研究了一下,
我用时间的Long生成62进制的数 -> 按照需求随机String长度拼接，返回
代码如下：
类：RandomGeneration，Long.toString()这个方法是可以转化为2-36进制，下一个类LongToStringMax62补充转化为62进制
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.UUID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class RandomGeneration {
private static final Logger logger = LoggerFactory.getLogger(RandomGeneration.class);
// 定义所有的字符组成的串
final static char[] allChar = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9' , 'a' , 'b' ,
'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
'o' , 'p' , 'q' , 'r' , 's' , 't' ,
'u' , 'v' , 'w' , 'x' , 'y' , 'z' ,
'A' , 'B' , 'C' , 'D' , 'E' , 'F' ,
'G' , 'H' , 'I' , 'J' , 'K' , 'L' ,
'M' , 'N' , 'O' , 'P' , 'Q' , 'R' ,
'S' , 'T' , 'U' , 'V' , 'W' , 'X' ,
'Y' , 'Z'
};
final static char[] allCharUpper = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9' , 'A' , 'B' ,
'C' , 'D' , 'E' , 'F' , 'G' , 'H' ,
'I' , 'J' , 'K' , 'L' , 'M' , 'N' ,
'O' , 'P' , 'Q' , 'R' , 'S' , 'T' ,
'U' , 'V' , 'W' , 'X' , 'Y' , 'Z'
};
final static char[] allCharLower = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9' , 'a' , 'b' ,
'c' , 'd' , 'e' , 'f' , 'g' , 'h' ,
'i' , 'j' , 'k' , 'l' , 'm' , 'n' ,
'o' , 'p' , 'q' , 'r' , 's' , 't' ,
'u' , 'v' , 'w' , 'x' , 'y' , 'z'
};
// 定义所有的小写字符组成的串（不包括数字）
final static char[] letterChar = {
'a' , 'b' , 'c' , 'd' , 'e' , 'f' ,
'g' , 'h' , 'i' , 'j' , 'k' , 'l' ,
'm' , 'n' , 'o' , 'p' , 'q' , 'r' ,
's' , 't' , 'u' , 'v' , 'w' , 'x' ,
'y' , 'z' , 'A' , 'B' , 'C' , 'D' ,
'E' , 'F' , 'G' , 'H' , 'I' , 'J' ,
'K' , 'L' , 'M' , 'N' , 'O' , 'P' ,
'Q' , 'R' , 'S' , 'T' , 'U' , 'V' ,
'W' , 'X' , 'Y' , 'Z'
};
final static char[] letterCharUpper = {
'A' , 'B' , 'C' , 'D' , 'E' , 'F' ,
'G' , 'H' , 'I' , 'J' , 'K' , 'L' ,
'M' , 'N' , 'O' , 'P' , 'Q' , 'R' ,
'S' , 'T' , 'U' , 'V' , 'W' , 'X' ,
'Y' , 'Z'
};
final static char[] letterCharLower = {
'a' , 'b' , 'c' , 'd' , 'e' , 'f' ,
'g' , 'h' , 'i' , 'j' , 'k' , 'l' ,
'm' , 'n' , 'o' , 'p' , 'q' , 'r' ,
's' , 't' , 'u' , 'v' , 'w' , 'x' ,
'y' , 'z'
};
// 定义所有的数字字符组成的串
final static char[] numberChar = {
'0' , '1' , '2' , '3' , '4' , '5' ,
'6' , '7' , '8' , '9'
};
/**
* 生成长度为length的随机字符串（包括字母和数字）
* @param length 需要生成的字符串长度
* @param flag 需要生成的字符大小写转换：0不变；1大写；2小写;其它不变
* @return
*/
public static String generateStrToLength(int length, int flag) {
StringBuffer respStr = new StringBuffer();
Random random = new Random();
if(0 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(allChar[random.nextInt(62)]);
}
}else if(1 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(allCharUpper[random.nextInt(36)]);
}
}else if(2 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(allCharLower[random.nextInt(36)]);
}
}else{
for (int i = 0; i < length; i++) {
respStr.append(allChar[random.nextInt(62)]);
}
}
return respStr.toString();
}
/**
* 产生长度为length的随机字符串（只包括字母）
* @param length 需要生成的字符串长度
* @param flag 需要生成的字符大小写转换：0不变；1大写；2小写;其它不变
* @return
*/
public static String generateLetterStrToLength(int length, int flag) {
StringBuffer respStr = new StringBuffer();
Random random = new Random();
if(0 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(letterChar[random.nextInt(52)]);
}
}else if(1 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(letterCharUpper[random.nextInt(26)]);
}
}else if(2 == flag) {
for (int i = 0; i < length; i++) {
respStr.append(letterCharLower[random.nextInt(26)]);
}
}else{
for (int i = 0; i < length; i++) {
respStr.append(letterChar[random.nextInt(52)]);
}
}
return respStr.toString();
}
/**
* 产生长度为length的随机字符串（只包括数字）
* @param length
* @return
*/
public static String generateNumberStrToLength(int length) {
StringBuffer respStr = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
respStr.append(numberChar[random.nextInt(10)]);
}
return respStr.toString();
}
/**
* 按照给定字符串随机生成长度为length的字符串
* @param randomString 需要随机的String
* @param length 需要生成的字符串长度
* @param flag 需要生成的字符大小写转换：0不变；1大写；2小写;其它不变
* @return
*/
public static String generateStrToLength(String randomString, int length, int flag) {
StringBuffer respStr = new StringBuffer();
Random random = new Random();
for (int i = 0; i < length; i++) {
respStr.append(randomString.charAt(random.nextInt(randomString.length())));
//respStr.append(LongToStringMax62.digits[(random.nextInt(62))]);
}
String respString = respStr.toString();
if(1 == flag) {
respString.toUpperCase();
}else if(2 == flag) {
respString.toLowerCase();
}
return respString;
}
/**
* 返回日期当前转化规定格式String
* @param date
* @param format
* @return
*/
public static String generateStrToDate(Object date, String format){
//Date date = new Date();
//"yyMMddHHmmssSSS"
SimpleDateFormat sdf = new SimpleDateFormat(format);
return sdf.format(date);
}
/**
* 通过UUID生成String
* @return
*/
public static String randomUUID(){
String uuid = java.util.UUID.randomUUID().toString();
uuid = uuid.replaceAll("-", "");
return uuid;
}
/**
* Math.random()生成String 注：(length > 1 && length < 10)
* @param length (length > 1 && length < 10)
* @return
*/
public static String mathRandom(int length){
return String.valueOf((int)((Math.random()*9+1)*Math.pow(10, length-1)));
}
/**
* 时间Long转化规定进制长度为Length的String(不满足长度时随机数字大小写字母补全长度)
* Long最大值转化36进制=1y2p0ij32e8e7
*
* @param date 时间转化为的Long('Thu Dec 14 09:48:29 CST 2017'转化为36进制为'jb5tsuvz')
* @param base 进制(2 <= base <= 36)
* @param length 长度(length >= 时间生成的规定进制数的长度,若length < 时间生成的规定进制数的长度 时建议根据实际需求选取其它方法)
* @return
*/
public static String generateStrToBase36(Long date, int base, int length){
StringBuffer respStr = new StringBuffer();
respStr.append(Long.toString(date, base));
if(respStr.length() < length){
//logger.info(respStr.toString());
Random random = new Random();
int j = length - respStr.length();
for (int i = 0; i < j; i++) {
respStr.append(allChar[(random.nextInt(62))]);
}
}else if(respStr.length() > length){
StringBuffer respStrLog = new StringBuffer();
//这种情况建议根据实际需求选取其它方法，若看到下面日志输出，请及时更换方法
respStrLog.append("length < ");
respStrLog.append(date);
respStrLog.append("生成的");
respStrLog.append(base);
respStrLog.append("进制数(");
respStrLog.append(respStr);
respStrLog.append(")的长度");
respStrLog.append(respStr.length());
respStrLog.append("，建议根据实际需求选取其它生成方法！！！");
logger.info(respStrLog.toString());
return respStr.substring(respStr.length() - length, respStr.length());
}
return respStr.toString();
}
/**
* 时间Long转化规定进制长度为Length的String(不满足长度时随机数字大小写字母补全长度)
* Long最大值转化62进制=aZl8N0y58M7
*
* @param date 时间转化为的Long('Thu Dec 14 17:19:29 CST 2017'转化为62进制为'qDLU7DO')
* @param base 进制(2 <= base <= 62)
* @param length 长度(length >= 时间生成的规定进制数的长度,若length < 时间生成的规定进制数的长度 时建议根据实际需求选取其它方法)
* @return
*/
public static String generateStrToBase62(Long date, int base, int length){
StringBuffer respStr = new StringBuffer();
respStr.append(LongToStringMax62.toString(date, base));
if(respStr.length() < length){
//logger.info(respStr.toString());
Random random = new Random();
int j = length - respStr.length();
for (int i = 0; i < j; i++) {
respStr.append(allChar[(random.nextInt(62))]);
}
}else if(respStr.length() > length){
StringBuffer respStrLog = new StringBuffer();
//这种情况建议根据实际需求选取其它方法，若看到下面日志输出，请及时更换方法
respStrLog.append("length < ");
respStrLog.append(date);
respStrLog.append("生成的");
respStrLog.append(base);
respStrLog.append("进制数(");
respStrLog.append(respStr);
respStrLog.append(")的长度");
respStrLog.append(respStr.length());
respStrLog.append("，建议根据实际需求选取其它生成方法！！！");
logger.info(respStrLog.toString());
return respStr.substring(respStr.length() - length, respStr.length());
}
return respStr.toString();
}
public static void main(String[] args) {
Date date1 = new Date();
for (int i = 0 ; i < 10000 ; i++){
Date date = new Date();
generateStrToBase62(date.getTime(), 62, 15);
}
Date date2 = new Date();
System.out.println("62=" + (date2.getTime() - date1.getTime()));
Date date4 = new Date();
for (int i = 0 ; i < 10000 ; i++){
Date date3 = new Date();
generateStrToBase36(date3.getTime(), 36, 15);
}
Date date5 = new Date();
System.out.println("36=" + (date5.getTime() - date4.getTime()));
}
}类：LongToStringMax62
public class LongToStringMax62 {
/**
* 用于从字符串转换和从字符串转换的最大基数。这个字段的常量值是基数转换方法中允许基数参数的最大值
*/
public static final int MAX_RADIX = 62;
/**
* 将long转化为指定进制
* @param i
* @param radix
* @return
*/
public static String toString(long i, int radix) {
if (radix < Character.MIN_RADIX || radix > MAX_RADIX)
radix = 10;
if (radix == 10)
return toString(i);
char[] buf = new char[65];
int charPos = 64;
boolean negative = (i < 0);
if (!negative) {
i = -i;
}
while (i <= -radix) {
buf[charPos--] = RandomGeneration.allChar[(int)(-(i % radix))];
i = i / radix;
}
buf[charPos] = RandomGeneration.allChar[(int)(-i)];
if (negative) {
buf[--charPos] = '-';
}
return new String(buf, charPos, (65 - charPos));
}
/**
* 进制不在2<进制数<62进制或进制为10进制时 进行的操作
* @param i
* @return
*/
public static String toString(long i) {
if (i == Long.MIN_VALUE)
return "-9223372036854775808";
int size = (i < 0) ? stringSize(-i) + 1 : stringSize(i);
char[] buf = new char[size];
getChars(i, size, buf);
//return new String(buf, true);
return new String(buf);
}
// Requires positive x
static int stringSize(long x) {
long p = 10;
for (int i=1; i<19; i++) {
if (x < p)
return i;
p = 10*p;
}
return 19;
}
/**
* 进制不在2<进制数<62进制或进制为10进制时 进行的操作
*/
static void getChars(long i, int index, char[] buf) {
long q;
int r;
int charPos = index;
char sign = 0;
if (i < 0) {
sign = '-';
i = -i;
}
// Get 2 digits/iteration using longs until quotient fits into an int
while (i > Integer.MAX_VALUE) {
q = i / 100;
// really: r = i - (q * 100);
r = (int)(i - ((q << 6) + (q << 5) + (q << 2)));
i = q;
buf[--charPos] = DigitOnes[r];
buf[--charPos] = DigitTens[r];
}
// Get 2 digits/iteration using ints
int q2;
int i2 = (int)i;
while (i2 >= 65536) {
q2 = i2 / 100;
// really: r = i2 - (q * 100);
r = i2 - ((q2 << 6) + (q2 << 5) + (q2 << 2));
i2 = q2;
buf[--charPos] = DigitOnes[r];
buf[--charPos] = DigitTens[r];
}
// Fall thru to fast mode for smaller numbers
// assert(i2 <= 65536, i2);
for (;;) {
q2 = (i2 * 52429) >>> (16+3);
r = i2 - ((q2 << 3) + (q2 << 1)); // r = i2-(q2*10) ...
buf[--charPos] = RandomGeneration.allChar[r];
i2 = q2;
if (i2 == 0) break;
}
if (sign != 0) {
buf[--charPos] = sign;
}
}
final static char [] DigitTens = {
'0', '0', '0', '0', '0', '0', '0', '0', '0', '0',
'1', '1', '1', '1', '1', '1', '1', '1', '1', '1',
'2', '2', '2', '2', '2', '2', '2', '2', '2', '2',
'3', '3', '3', '3', '3', '3', '3', '3', '3', '3',
'4', '4', '4', '4', '4', '4', '4', '4', '4', '4',
'5', '5', '5', '5', '5', '5', '5', '5', '5', '5',
'6', '6', '6', '6', '6', '6', '6', '6', '6', '6',
'7', '7', '7', '7', '7', '7', '7', '7', '7', '7',
'8', '8', '8', '8', '8', '8', '8', '8', '8', '8',
'9', '9', '9', '9', '9', '9', '9', '9', '9', '9',
} ;
final static char [] DigitOnes = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
} ;
}
希望对你有帮助，祝你有一个好心情，加油！
若有错误、不全、可优化的点，欢迎纠正与补充！