C＃緩衝GZipStream壓縮

我正在編寫database備份功能，從System.Diagnostics.Process object，從StandardOutput (StreamReader)屬性讀取。我已成功寫入純文件。C＃緩衝GZipStream壓縮

//This code successfully wrote text files. 
StreamWriter f = new StreamWriter(BackupPath); 
while (true) { 
    //RaiseProgressedEvent(new DBProgressEventArgs(dbsize, progress, "Writing backup file")); 

    int buffsize = 512; 
    char[] buff = new char[buffsize]; 
    int count = p.StandardOutput.ReadBlock(buff, 0, buff.Length); 
    if (count == 0) break; 
    // If no more data, trim the char array 
    if (p.StandardOutput.Peek() < 0) buff = (from c in buff where c > 0 select c).ToArray(); 

    f.Write(buff, 0, count); 
    progress += buffsize; 
} 
f.Close();

但是，當我更改爲GZipStream：

//This code yields a broken gzip file. 
//*2 lines changed: StreamWriter changed into FileStream. 
FileStream fs = File.Create(BackupPath); 
GZipStream zipStream = new GZipStream(fs, CompressionMode.Compress, true); 

while (true) { 
    RaiseProgressedEvent(new DBProgressEventArgs(dbsize, progress, "Writing backup file")); 

    int buffsize = 512; 
    char[] buff = new char[buffsize]; 
    int count = p.StandardOutput.ReadBlock(buff, 0, buff.Length); 
    if (count == 0) break; 
    if (p.StandardOutput.Peek() < 0) buff = (from c in buff where c > 0 select c).ToArray(); 

    //With UTF 8 Encoding, write to gzipstream. 
    //f.write changed into the following 2 lines: 
    Encoding enc = Encoding.UTF8; 
    zipStream.Write(enc.GetBytes(buff), 0, enc.GetByteCount(buff)); 

    progress += buffsize; 
} 
fs.Close();

所得GZip文件不完整/斷開。當用7zip進行解壓縮，然後用notepad++打開時，幾乎所有的文本都很好，只有靠近文件末尾的一些字節丟失。我不確定，但也許錯誤是：zipStream.Write(enc.GetBytes(buff), 0, enc.GetByteCount(buff)); 也許與enc.GetByteCount(buff)有關。

讀取緩衝爲多線程，用於處理大文件。那麼......爲什麼最後的字節會丟失？我在哪裏做錯了？

來源

2016-09-15 Fandi Susanto

有什麼可疑的是，你從來沒有關閉/處置你的'zipStream'。這可能沒有必要，但這是我第一次嘗試。 – hvd

是的，你正在關閉一些未顯示的'fs'，但可能是底層文件流。如果不讓GZipStream完成工作，你無法關閉它。總是關閉最後一個，而不是鏈中的第一個。 –

fs是代碼片段頂部的FileStream。 –

試着這麼做：

使用的GZipStream一個構造函數，關閉FileStream後Dispose

using(FileStream fs = File.Create(BackupPath)) 
using(GZipStream zipStream = new GZipStream(fs, CompressionMode.Compress, false)) 
{ 

while (true) { 
    RaiseProgressedEvent(new DBProgressEventArgs(dbsize, progress, "Writing backup file")); 

int buffsize = 512; 
char[] buff = new char[buffsize]; 
int count = p.StandardOutput.ReadBlock(buff, 0, buff.Length); 
if (count == 0) break; 
if (p.StandardOutput.Peek() < 0) buff = (from c in buff where c > 0 select c).ToArray(); 

//With UTF 8 Encoding, write to gzipstream. 
//f.write changed into the following 2 lines: 
Encoding enc = Encoding.UTF8; 
zipStream.Write(enc.GetBytes(buff), 0, enc.GetByteCount(buff)); 

progress += buffsize; 
} 
}

來源

2016-09-15 05:28:48

@hvd註釋（關閉zipstream）中包含'FileStream'和'GZipStream'解決了這個問題。但是這個答案也解決了這個問題。不知何故，這個代碼更整潔。謝謝。 –

如果你想要的是拉鍊在同一文件夾中的文件，那麼我嘗試下面的代碼正在工作。

private void button1_Click(object sender, EventArgs e) 
    { 

     try 
     { 
      FileInfo fi = new FileInfo(@"F:\Harris\abc.txt"); 
      FileStream fs = File.OpenRead(@"F:\Harris\abc.txt"); 
      using (FileStream compressedFileStream = File.Create(fi.FullName + ".gz")) 
      { 
       using (GZipStream compressionStream = new GZipStream(compressedFileStream, 
       System.IO.Compression.CompressionMode.Compress, true)) 
       { 
        fs.CopyTo(compressionStream); 
       } 
      }//end using 

      MessageBox.Show("Done"); 
     } 
     catch (Exception ex) 
     { 
      MessageBox.Show(ex.Message); 
     } 
     finally { } 
    }

來源

2016-09-15 05:57:22

C＃緩衝GZipStream壓縮

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