using ICSharpCode.SharpZipLib.BZip2;
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using ICSharpCode.SharpZipLib.GZip;
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using ICSharpCode.SharpZipLib.Zip;
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Linq;
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using System.Text;
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using System.Threading.Tasks;
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namespace IStation
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{
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public class Compression
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{
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/// <summary>
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/// 压缩方式。
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/// </summary>
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public enum CompressionType
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{
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/// <summary>
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/// GZip 压缩格式
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/// </summary>
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GZip,
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/// <summary>
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/// BZip2 压缩格式
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/// </summary>
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BZip2,
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/// <summary>
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/// Zip 压缩格式
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/// </summary>
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Zip
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}
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/// <summary>
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/// 使用 SharpZipLib 进行压缩的辅助类，简化对字节数组和字符串进行压缩的操作。
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/// </summary>
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public class CompressionHelper
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{
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/// <summary>
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/// 压缩供应者，默认为 GZip。
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/// </summary>
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public static CompressionType CompressionProvider = CompressionType.GZip;
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#region Public methods
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/// <summary>
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/// 从原始字节数组生成已压缩的字节数组。
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/// </summary>
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/// <param name="bytesToCompress">原始字节数组。</param>
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/// <returns>返回已压缩的字节数组</returns>
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public static byte[] Compress(byte[] bytesToCompress)
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{
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MemoryStream ms = new MemoryStream();
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Stream s = OutputStream(ms);
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s.Write(bytesToCompress, 0, bytesToCompress.Length);
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s.Close();
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return ms.ToArray();
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}
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/// <summary>
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/// 从原始字符串生成已压缩的字符串。
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/// </summary>
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/// <param name="stringToCompress">原始字符串。</param>
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/// <returns>返回已压缩的字符串。</returns>
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public static string Compress(string stringToCompress)
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{
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byte[] compressedData = CompressToByte(stringToCompress);
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string strOut = Convert.ToBase64String(compressedData);
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return strOut;
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}
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/// <summary>
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/// 从原始字符串生成已压缩的字节数组。
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/// </summary>
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/// <param name="stringToCompress">原始字符串。</param>
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/// <returns>返回已压缩的字节数组。</returns>
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public static byte[] CompressToByte(string stringToCompress)
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{
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byte[] bytData = Encoding.Unicode.GetBytes(stringToCompress);
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return Compress(bytData);
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}
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/// <summary>
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/// 从已压缩的字符串生成原始字符串。
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/// </summary>
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/// <param name="stringToDecompress">已压缩的字符串。</param>
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/// <returns>返回原始字符串。</returns>
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public string DeCompress(string stringToDecompress)
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{
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string outString = string.Empty;
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if (stringToDecompress == null)
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{
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throw new ArgumentNullException("stringToDecompress", "You tried to use an empty string");
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}
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try
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{
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byte[] inArr = Convert.FromBase64String(stringToDecompress.Trim());
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outString = Encoding.Unicode.GetString(DeCompress(inArr));
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}
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catch (NullReferenceException nEx)
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{
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return nEx.Message;
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}
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return outString;
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}
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/// <summary>
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/// 从已压缩的字节数组生成原始字节数组。
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/// </summary>
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/// <param name="bytesToDecompress">已压缩的字节数组。</param>
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/// <returns>返回原始字节数组。</returns>
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public static byte[] DeCompress(byte[] bytesToDecompress)
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{
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byte[] writeData = new byte[4096];
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Stream s2 = InputStream(new MemoryStream(bytesToDecompress));
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MemoryStream outStream = new MemoryStream();
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while (true)
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{
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int size = s2.Read(writeData, 0, writeData.Length);
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if (size > 0)
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{
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outStream.Write(writeData, 0, size);
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}
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else
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{
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break;
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}
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}
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s2.Close();
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byte[] outArr = outStream.ToArray();
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outStream.Close();
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return outArr;
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}
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#endregion
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#region Private methods
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/// <summary>
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/// 从给定的流生成压缩输出流。
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/// </summary>
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/// <param name="inputStream">原始流。</param>
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/// <returns>返回压缩输出流。</returns>
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private static Stream OutputStream(Stream inputStream)
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{
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switch (CompressionProvider)
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{
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case CompressionType.BZip2:
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return new BZip2OutputStream(inputStream);
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case CompressionType.GZip:
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return new GZipOutputStream(inputStream);
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case CompressionType.Zip:
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return new ZipOutputStream(inputStream);
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default:
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return new GZipOutputStream(inputStream);
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}
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}
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/// <summary>
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/// 从给定的流生成压缩输入流。
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/// </summary>
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/// <param name="inputStream">原始流。</param>
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/// <returns>返回压缩输入流。</returns>
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private static Stream InputStream(Stream inputStream)
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{
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switch (CompressionProvider)
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{
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case CompressionType.BZip2:
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return new BZip2InputStream(inputStream);
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case CompressionType.GZip:
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return new GZipInputStream(inputStream);
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case CompressionType.Zip:
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return new ZipInputStream(inputStream);
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default:
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return new GZipInputStream(inputStream);
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}
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}
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#endregion
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}
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}
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}
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