Java Punycode 中文 URL 编码轮子

MrXiaoM

你有没有遇到过一个 Java 程序不支持解析中文域名的情况?
虽然把域名给 Punycode 编码之后能够直接用，但是编码后的域名很不好记。
所以我去找了 Punycode 编码的方法，写了个简单的轮子，将中文域名转成能直接用的

应用场景：https://github.com/DoomsdaySociety/ChineseDomainSupport

已知缺点：域名后缀为【.中国、.我爱你】等中文域名后缀不转换

src:
https://blog.csdn.net/qq_35312082/article/details/118271152

[Java] 纯文本查看 复制代码

public class Punycode {
        private static int TMIN = 1;
        private static int TMAX = 26;
        private static int BASE = 36;
        private static int INITIAL_N = 128;
        private static int INITIAL_BIAS = 72;
        private static int DAMP = 700;
        private static int SKEW = 38;
        private static char DELIMITER = '-';

        public static String encodeURL(String url) {
                if (!url.contains("."))
                        return url;
                String mainContent = url.substring(0, url.lastIndexOf("."));
                String prefix = mainContent.contains(".") ? mainContent.substring(0, mainContent.lastIndexOf(".") + 1) : "";
                if (mainContent.contains("."))
                        mainContent = mainContent.substring(mainContent.lastIndexOf(".") + 1);
                mainContent = Punycode.encode(mainContent, "xn--");
                String suffix = url.substring(url.lastIndexOf("."));
                return prefix + mainContent + suffix;
        }

        /**
         * 
         * Punycodes a unicode string. THIS IS NOT SUITABLE FOR UNICODE AND LETTER
         * MIXING
         *
         * @Param input Unicode string.
         * 
         * @Return Punycoded string, but original text for throw an exception
         * 
         */
        public static String encode(String input) {
                return Punycode.encode(input, "");
        }

        /**
         * 
         * Punycodes a unicode string. THIS IS NOT SUITABLE FOR UNICODE AND LETTER
         * MIXING
         *
         * @param input Unicode string.
         * 
         * @return Punycoded string, but original text for throw an exception
         * 
         */
        public static String encode(String input, String successPrefix) {
                int n = INITIAL_N;
                int delta = 0;
                int bias = INITIAL_BIAS;
                StringBuilder output = new StringBuilder();
                int b = 0;
                for (int i = 0; i < input.length(); i++) {
                        char c = input.charAt(i);
                        if (isBasic(c)) {
                                output.append(c);
                                b++;
                        }
                }
                if(b >= input.length()) return output.toString();
                if (b > 0) {
                        output.append(DELIMITER);
                }
                int h = b;
                while (h < input.length()) {
                        int m = Integer.MAX_VALUE;
                        for (int i = 0; i < input.length(); i++) {
                                int c = input.charAt(i);
                                if (c >= n && c < m) {
                                        m = c;
                                }
                        }
                        if (m - n > (Integer.MAX_VALUE - delta) / (h + 1)) {
                                return input;
                        }
                        delta = delta + (m - n) * (h + 1);
                        n = m;
                        for (int j = 0; j < input.length(); j++) {
                                int c = input.charAt(j);
                                if (c < n) {
                                        delta++;
                                        if (0 == delta) {
                                                return input;
                                        }
                                }
                                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++;
                }
                output.insert(0, successPrefix);
                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;
        }

        private static int digit2codepoint(int d) {
                if (d < 26) {
                        return d + 'a';
                } else if (d < 36) {
                        return d - 26 + '0';
                } else {
                        return d;
                }
        }
}