using System;
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using System.Collections.Generic;
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using System.Linq;
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namespace Link.Common
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{
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/// <summary>
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/// 地址工具
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/// </summary>
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public class LinkUtil
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{
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/// <summary>
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/// 基础62位字符
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/// </summary>
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private const string _baseKeys = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
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/// <summary>
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/// 幂数
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/// </summary>
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private static readonly int _exponent = _baseKeys.Length;
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/// <summary>
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/// 十进制转62进制
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/// </summary>
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/// <param name="value"></param>
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/// <returns></returns>
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public static string ConvertTo64(long value)
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{
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string result = string.Empty;
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do
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{
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long index = value % _exponent;
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result = _baseKeys[(int)index] + result;
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value = (value - index) / _exponent;
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}
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while (value > 0);
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return result;
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}
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/// <summary>
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/// 混淆十进制转62进制
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/// </summary>
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/// <param name="value"></param>
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/// <returns></returns>
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public static string MixValueConvertTo64(long value)
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{
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long mixValue = InsertRandomBitPer5Bits(value);
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string result = string.Empty;
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do
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{
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long index = mixValue % _exponent;
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result = _baseKeys[(int)index] + result;
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mixValue = (mixValue - index) / _exponent;
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}
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while (mixValue > 0);
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return result;
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}
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/// <summary>
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/// 62进制转10进制
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/// </summary>
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/// <param name="value"></param>
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/// <returns></returns>
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public static decimal ConvertTo10(string value)
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{
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decimal result = 0;
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for (int i = 0; i < value.Length; i++)
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{
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int x = value.Length - i - 1;
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result += _baseKeys.IndexOf(value[i]) * Pow(_exponent, x);
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}
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return result;
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}
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/// <summary>
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/// 一个数据的N次方
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/// </summary>
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/// <param name="baseNo"></param>
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/// <param name="x"></param>
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/// <returns></returns>
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private static decimal Pow(decimal baseNo, decimal x)
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{
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//1 will be the result for any number's power 0.
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decimal value = 1;
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while (x > 0)
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{
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value = value * baseNo;
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x--;
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}
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return value;
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}
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/// <summary>
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/// 每5位插一个随机位
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/// </summary>
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/// <param name="val"></param>
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/// <returns></returns>
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private static long InsertRandomBitPer5Bits(long val)
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{
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long result = val;
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long high = val;
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for (int i = 0; i < 10; i++)
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{
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if (high == 0)
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{
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break;
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}
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Random random = new Random();
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long num = random.Next(0, 2);
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int pos = 5 + 5 * i + i;
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high = result >> pos;
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result = ((high << 1 | num) << pos) | (result & RightMove(-1L, 64 - pos));
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}
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return result;
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}
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/// <summary>
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/// 无符号右移, 相当于java里的 value>>>pos
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/// </summary>
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/// <param name="value"></param>
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/// <param name="pos"></param>
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/// <returns></returns>
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public static long RightMove(long value, int pos)
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{
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//移动 0 位时直接返回原值
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if (pos != 0)
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{
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// int.MaxValue = 0x7FFFFFFF 整数最大值
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long mask = long.MaxValue;
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//无符号整数最高位不表示正负但操作数还是有符号的，有符号数右移1位，正数时高位补0，负数时高位补1
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value = value >> 1;
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//和整数最大值进行逻辑与运算，运算后的结果为忽略表示正负值的最高位
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value = value & mask;
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//逻辑运算后的值无符号，对无符号的值直接做右移运算，计算剩下的位
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value = value >> pos - 1;
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}
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return value;
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}
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}
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}
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