C# 缓冲 GZipStream 压缩

Question

我正在写一个database备份功能，读取System.Diagnostics.Process object ，来自StandardOutput (StreamReader)属性(property)。我已成功写入纯文件。

//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();

但是当我更改为GZipStream时:

//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();

结果GZip文件不完整/损坏。当用 7zip 解压时然后用 notepad++ 打开，几乎所有文本都是好的，只有文件末尾附近的一些字节丢失了。我不确定，但也许错误就在附近:zipStream.Write(enc.GetBytes(buff), 0, enc.GetByteCount(buff)); 也许与enc.GetByteCount(buff)有关.

读取是为了多线程而缓冲的，用于处理大文件。那么...为什么最后一个字节丢失了？我哪里做错了？

Answer 1

尝试如下:

• 使用GZipStream的构造函数，关闭FileStream post 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;
  }
  }