cn.hutool.core.codec.PunyCode Maven / Gradle / Ivy
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package cn.hutool.core.codec;
import cn.hutool.core.exceptions.UtilException;
import cn.hutool.core.lang.Assert;
import cn.hutool.core.util.CharUtil;
import cn.hutool.core.util.StrUtil;
import java.util.List;
/**
* Punycode是一个根据RFC 3492标准而制定的编码系统，主要用于把域名从地方语言所采用的Unicode编码转换成为可用于DNS系统的编码
*
* 参考：https://blog.csdn.net/a19881029/article/details/18262671
*
* @author looly
* @since 5.5.2
*/
public class PunyCode {
private static final int TMIN = 1;
private static final int TMAX = 26;
private static final int BASE = 36;
private static final int INITIAL_N = 128;
private static final int INITIAL_BIAS = 72;
private static final int DAMP = 700;
private static final int SKEW = 38;
private static final char DELIMITER = '-';
public static final String PUNY_CODE_PREFIX = "xn--";
/**
* punycode转码域名
*
* @param domain 域名
* @return 编码后的域名
* @throws UtilException 计算异常
*/
public static String encodeDomain(String domain) throws UtilException {
Assert.notNull(domain, "domain must not be null!");
final List split = StrUtil.split(domain, CharUtil.DOT);
final StringBuilder result = new StringBuilder(domain.length() * 4);
for (final String str : split) {
if (result.length() != 0) {
result.append(CharUtil.DOT);
}
result.append(encode(str, true));
}
return result.toString();
}
/**
* 将内容编码为PunyCode
*
* @param input 字符串
* @return PunyCode字符串
* @throws UtilException 计算异常
*/
public static String encode(CharSequence input) throws UtilException {
return encode(input, false);
}
/**
* 将内容编码为PunyCode
*
* @param input 字符串
* @param withPrefix 是否包含 "xn--"前缀
* @return PunyCode字符串
* @throws UtilException 计算异常
*/
public static String encode(CharSequence input, boolean withPrefix) throws UtilException {
Assert.notNull(input, "input must not be null!");
int n = INITIAL_N;
int delta = 0;
int bias = INITIAL_BIAS;
StringBuilder output = new StringBuilder();
// Copy all basic code points to the output
final int length = input.length();
int b = 0;
for (int i = 0; i < length; i++) {
char c = input.charAt(i);
if (isBasic(c)) {
output.append(c);
b++;
}
}
// Append delimiter
if (b > 0) {
if(b == length){
// 无需要编码的字符
return output.toString();
}
output.append(DELIMITER);
}
int h = b;
while (h < length) {
int m = Integer.MAX_VALUE;
// Find the minimum code point >= n
for (int i = 0; i < length; i++) {
final char c = input.charAt(i);
if (c >= n && c < m) {
m = c;
}
}
if (m - n > (Integer.MAX_VALUE - delta) / (h + 1)) {
throw new UtilException("OVERFLOW");
}
delta = delta + (m - n) * (h + 1);
n = m;
for (int j = 0; j < length; j++) {
int c = input.charAt(j);
if (c < n) {
delta++;
if (0 == delta) {
throw new UtilException("OVERFLOW");
}
}
if (c == n) {
int q = delta;
for (int k = BASE; ; k += BASE) {
int t;
if (k <= bias) {
t = TMIN;
} else if (k >= bias + TMAX) {
t = TMAX;
} else {
t = k - bias;
}
if (q < t) {
break;
}
output.append((char) digit2codepoint(t + (q - t) % (BASE - t)));
q = (q - t) / (BASE - t);
}
output.append((char) digit2codepoint(q));
bias = adapt(delta, h + 1, h == b);
delta = 0;
h++;
}
}
delta++;
n++;
}
if (withPrefix) {
output.insert(0, PUNY_CODE_PREFIX);
}
return output.toString();
}
/**
* 解码punycode域名
*
* @param domain PunyCode域名
* @return 解码后的域名
* @throws UtilException 计算异常
*/
public static String decodeDomain(String domain) throws UtilException {
Assert.notNull(domain, "domain must not be null!");
final List split = StrUtil.split(domain, CharUtil.DOT);
final StringBuilder result = new StringBuilder(domain.length() / 4 + 1);
for (final String str : split) {
if (result.length() != 0) {
result.append(CharUtil.DOT);
}
result.append(StrUtil.startWithIgnoreEquals(str, PUNY_CODE_PREFIX) ? decode(str) : str);
}
return result.toString();
}
/**
* 解码 PunyCode为字符串
*
* @param input PunyCode
* @return 字符串
* @throws UtilException 计算异常
*/
public static String decode(String input) throws UtilException {
Assert.notNull(input, "input must not be null!");
input = StrUtil.removePrefixIgnoreCase(input, PUNY_CODE_PREFIX);
int n = INITIAL_N;
int i = 0;
int bias = INITIAL_BIAS;
StringBuilder output = new StringBuilder();
int d = input.lastIndexOf(DELIMITER);
if (d > 0) {
for (int j = 0; j < d; j++) {
final char c = input.charAt(j);
if (isBasic(c)) {
output.append(c);
}
}
d++;
} else {
d = 0;
}
final int length = input.length();
while (d < length) {
int oldi = i;
int w = 1;
for (int k = BASE; ; k += BASE) {
if (d == length) {
throw new UtilException("BAD_INPUT");
}
int c = input.charAt(d++);
int digit = codepoint2digit(c);
if (digit > (Integer.MAX_VALUE - i) / w) {
throw new UtilException("OVERFLOW");
}
i = i + digit * w;
int t;
if (k <= bias) {
t = TMIN;
} else if (k >= bias + TMAX) {
t = TMAX;
} else {
t = k - bias;
}
if (digit < t) {
break;
}
w = w * (BASE - t);
}
bias = adapt(i - oldi, output.length() + 1, oldi == 0);
if (i / (output.length() + 1) > Integer.MAX_VALUE - n) {
throw new UtilException("OVERFLOW");
}
n = n + i / (output.length() + 1);
i = i % (output.length() + 1);
output.insert(i, (char) n);
i++;
}
return output.toString();
}
private static int adapt(int delta, int numpoints, boolean first) {
if (first) {
delta = delta / DAMP;
} else {
delta = delta / 2;
}
delta = delta + (delta / numpoints);
int k = 0;
while (delta > ((BASE - TMIN) * TMAX) / 2) {
delta = delta / (BASE - TMIN);
k = k + BASE;
}
return k + ((BASE - TMIN + 1) * delta) / (delta + SKEW);
}
private static boolean isBasic(char c) {
return c < 0x80;
}
/**
* 将数字转为字符，对应关系为：
*
* 0 -> a
* 1 -> b
* ...
* 25 -> z
* 26 -> '0'
* ...
* 35 -> '9'
*
*
* @param d 输入字符
* @return 转换后的字符
* @throws UtilException 无效字符
*/
private static int digit2codepoint(int d) throws UtilException {
Assert.checkBetween(d, 0, 35);
if (d < 26) {
// 0..25 : 'a'..'z'
return d + 'a';
} else if (d < 36) {
// 26..35 : '0'..'9';
return d - 26 + '0';
} else {
throw new UtilException("BAD_INPUT");
}
}
/**
* 将字符转为数字，对应关系为：
*
* a -> 0
* b -> 1
* ...
* z -> 25
* '0' -> 26
* ...
* '9' -> 35
*
*
* @param c 输入字符
* @return 转换后的字符
* @throws UtilException 无效字符
*/
private static int codepoint2digit(int c) throws UtilException {
if (c - '0' < 10) {
// '0'..'9' : 26..35
return c - '0' + 26;
} else if (c - 'a' < 26) {
// 'a'..'z' : 0..25
return c - 'a';
} else {
throw new UtilException("BAD_INPUT");
}
}
}