C# 用 gzip 壓縮字串並取得 base64 字串

這個使用方式的效果是有但書的，當 Source 的重複率不高壓縮的效果就不會好，再加上 base64 就是用可見文字去表示 byte 值，這會讓 base64 後的結果比 byte array 還要長，所以壓縮率沒有到達一定的程度下，輸出反而會比 Source 的字串還要長。

原始碼

1. //using System.IO.Compression; 
2.  
3.  
4. void Main() 
5. { 
6.    string text = "OptionPostal,OptionClassType,OptionTalentItem"; 
7.    text.Length.Dump(); /* 45 */ 
8.  
9.    string compressBase64 = compress(text); 
10.    compressBase64.Length.Dump(); /* 76 */ 
11.    compressBase64.Dump();  
12.    /* H4sIAAAAAAAEAPMvKMnMzwvILy5JzNHxB3OccxKLi0MqC1Kh/JDEnNS8Es+S1FwAaY6qVC0AAAA= */ 
13.  
14.    string decompressText = decompress(compressBase64); 
15.    decompressText.Dump();  
16.    /* OptionPostal,OptionClassType,OptionTalentItem */ 
17.  
18.    text = "OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem"; 
19.    text.Length.Dump(); /* 183 */ 
20.  
21.    compressBase64 = compress(text); 
22.    compressBase64.Length.Dump(); /* 84 */ 
23.    compressBase64.Dump();  
24.    /* H4sIAAAAAAAEAPMvKMnMzwvILy5JzNHxB3OccxKLi0MqC1Kh/JDEnNS8Es+S1FyowCBQDQBPmlWktwAAAA== */ 
25.  
26. } 
27.  
28.  
29. /*壓縮*/ 
30. private static string compress(string text) 
31. { 
32.    if (string.IsNullOrEmpty(text)) { return text; } 
33.  
34.    byte[] buffer = Encoding.UTF8.GetBytes(text); 
35.  
36.    using (var outStream = new MemoryStream()) 
37.    using (var zip = new GZipStream(outStream, CompressionMode.Compress)) 
38.    { 
39.        zip.Write(buffer, 0, buffer.Length); 
40.        zip.Close(); 
41.  
42.        string compressedBase64 = Convert.ToBase64String(outStream.ToArray()); 
43.        return compressedBase64; 
44.    } 
45. } 
46.  
47.  
48. /*解壓縮*/ 
49. private static string decompress(string compressed) 
50. { 
51.    if (string.IsNullOrEmpty(compressed)) { return compressed; } 
52.  
53.    byte[] buffer = Convert.FromBase64String(compressed); 
54.  
55.    using (var inStream = new MemoryStream(buffer)) 
56.    using (var outStream = new MemoryStream()) 
57.    using (var zip = new GZipStream(inStream, CompressionMode.Decompress)) 
58.    { 
59.        zip.CopyTo(outStream); 
60.        zip.Close(); 
61.  
62.        string text = Encoding.UTF8.GetString(outStream.ToArray()); 
63.        return text; 
64.    } 
65. } 

//using System.IO.Compression;


void Main()
{
    string text = "OptionPostal,OptionClassType,OptionTalentItem";
    text.Length.Dump(); /* 45 */

    string compressBase64 = compress(text);
    compressBase64.Length.Dump(); /* 76 */
    compressBase64.Dump(); 
    /* H4sIAAAAAAAEAPMvKMnMzwvILy5JzNHxB3OccxKLi0MqC1Kh/JDEnNS8Es+S1FwAaY6qVC0AAAA= */

    string decompressText = decompress(compressBase64);
    decompressText.Dump(); 
    /* OptionPostal,OptionClassType,OptionTalentItem */

    text = "OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem,OptionPostal,OptionClassType,OptionTalentItem";
    text.Length.Dump(); /* 183 */

    compressBase64 = compress(text);
    compressBase64.Length.Dump(); /* 84 */
    compressBase64.Dump(); 
    /* H4sIAAAAAAAEAPMvKMnMzwvILy5JzNHxB3OccxKLi0MqC1Kh/JDEnNS8Es+S1FyowCBQDQBPmlWktwAAAA== */

}


/*壓縮*/
private static string compress(string text)
{
    if (string.IsNullOrEmpty(text)) { return text; }

    byte[] buffer = Encoding.UTF8.GetBytes(text);

    using (var outStream = new MemoryStream())
    using (var zip = new GZipStream(outStream, CompressionMode.Compress))
    {
        zip.Write(buffer, 0, buffer.Length);
        zip.Close();

        string compressedBase64 = Convert.ToBase64String(outStream.ToArray());
        return compressedBase64;
    }
}


/*解壓縮*/
private static string decompress(string compressed)
{
    if (string.IsNullOrEmpty(compressed)) { return compressed; }

    byte[] buffer = Convert.FromBase64String(compressed);

    using (var inStream = new MemoryStream(buffer))
    using (var outStream = new MemoryStream())
    using (var zip = new GZipStream(inStream, CompressionMode.Decompress))
    {
        zip.CopyTo(outStream);
        zip.Close();

        string text = Encoding.UTF8.GetString(outStream.ToArray());
        return text;
    }
}