新增6位全局邀请码工具

basic-util/src/main/java/ink/wgink/util/verification/share/ShareCodeUtil.java

@@ -0,0 +1,124 @@
+package ink.wgink.util.verification.share;
+
+import java.util.Arrays;
+
+/**
+ * When you feel like quitting. Think about why you started
+ * 当你想要放弃的时候，想想当初你为何开始
+ *
+ * @ClassName: ShareCodeUtil
+ * @Description: 分享码，全局唯一，长度6位
+ * @Author: wanggeng
+ * @Date: 2021/5/2 11:58 上午
+ * @Version: 1.0
+ */
+public class ShareCodeUtil {
+
+    /**
+     * 随机字符串
+     */
+    private static final char[] CHARS = new char[]{'F', 'L', 'G', 'W', '5', 'X', 'C', '3',
+            '9', 'Z', 'M', '6', '7', 'Y', 'R', 'T', '2', 'H', 'S', '8', 'D', 'V', 'E', 'J', '4', 'K',
+            'Q', 'P', 'U', 'A', 'N', 'B'};
+
+    private final static int CHARS_LENGTH = 32;
+    /**
+     * 邀请码长度
+     */
+    private final static int CODE_LENGTH = 6;
+    /**
+     * 随机数据
+     */
+    private final static long SLAT = 1234561L;
+    /**
+     * PRIME1 与 CHARS 的长度 L互质，可保证 ( id * PRIME1) % L 在 [0,L)上均匀分布
+     */
+    private final static int PRIME1 = 3;
+
+    /**
+     * PRIME2 与 CODE_LENGTH 互质，可保证 ( index * PRIME2) % CODE_LENGTH  在 [0，CODE_LENGTH）上均匀分布
+     */
+    private final static int PRIME2 = 11;
+
+    /**
+     * 生成邀请码
+     *
+     * @param id 唯一的id主键
+     * @return code
+     */
+    public static String gen(Long id) {
+        //补位
+        id = id * PRIME1 + SLAT;
+        //将 id 转换成32进制的值
+        long[] b = new long[CODE_LENGTH];
+        //32进制数
+        b[0] = id;
+        for (int i = 0; i < CODE_LENGTH - 1; i++) {
+            b[i + 1] = b[i] / CHARS_LENGTH;
+            //按位扩散
+            b[i] = (b[i] + i * b[0]) % CHARS_LENGTH;
+        }
+        b[5] = (b[0] + b[1] + b[2] + b[3] + b[4]) * PRIME1 % CHARS_LENGTH;
+
+        //进行混淆
+        long[] codeIndexArray = new long[CODE_LENGTH];
+        for (int i = 0; i < CODE_LENGTH; i++) {
+            codeIndexArray[i] = b[i * PRIME2 % CODE_LENGTH];
+        }
+
+        StringBuilder buffer = new StringBuilder();
+        Arrays.stream(codeIndexArray).boxed().map(Long::intValue).map(t -> CHARS[t]).forEach(buffer::append);
+        return buffer.toString();
+    }
+
+    /**
+     * 将邀请码解密成原来的id
+     *
+     * @param code 邀请码
+     * @return id
+     */
+    public static Long decode(String code) {
+        if (code.length() != CODE_LENGTH) {
+            return null;
+        }
+        //将字符还原成对应数字
+        long[] a = new long[CODE_LENGTH];
+        for (int i = 0; i < CODE_LENGTH; i++) {
+            char c = code.charAt(i);
+            int index = findIndex(c);
+            if (index == -1) {
+                //异常字符串
+                return null;
+            }
+            a[i * PRIME2 % CODE_LENGTH] = index;
+        }
+
+        long[] b = new long[CODE_LENGTH];
+        for (int i = CODE_LENGTH - 2; i >= 0; i--) {
+            b[i] = (a[i] - a[0] * i + CHARS_LENGTH * i) % CHARS_LENGTH;
+        }
+
+        long res = 0;
+        for (int i = CODE_LENGTH - 2; i >= 0; i--) {
+            res += b[i];
+            res *= (i > 0 ? CHARS_LENGTH : 1);
+        }
+        return (res - SLAT) / PRIME1;
+    }
+
+    /**
+     * 查找对应字符的index
+     *
+     * @param c 字符
+     * @return index
+     */
+    private static int findIndex(char c) {
+        for (int i = 0; i < CHARS_LENGTH; i++) {
+            if (CHARS[i] == c) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+}