异常后关闭流

时间:2010-01-21 22:24:06

标签: c# .net stream serialization

我打开一个流,然后反序列化流中的数据。但是,我在SavedEventSet对象中添加了一个成员,所以现在当我尝试打开一个旧文件时,它会在反序列化行上抛出异常。

这对我来说没问题(现在),但问题是我处理异常,但从不关闭流(因为异常发生在我关闭流之前),所以当我再次尝试打开文件时,它不会让我因为它正在使用中。

如何在此异常后关闭流?如果我将stream.Close()放在catch或finally中,它会抱怨尝试访问未分配的局部变量。看起来不好的做法就是打开我知道的随机文件。有没有办法以类似于空构造函数的方式打开流,所以它看起来像是被分配了?

由于

SavedEventSet sES;
OpenFileDialog oFD = new OpenFileDialog();
Stream stream;
BinaryFormatter bF;

try
{
    oFD.InitialDirectory = this.path;
    oFD.Title = "Open Event Saved File.";
    oFD.ShowDialog();

    if(oFD.FileName.Contains(".sav"))
    {
        stream = File.Open(oFD.FileName, FileMode.Open);
        bF = new BinaryFormatter();

        sES = (SavedEventSet)bF.Deserialize(stream);
        stream.Close();

    }
}
catch (Exception ex)
{
    stream.Close();
    /*handle Exception*/
}

4 个答案:

答案 0 :(得分:27)

你可以使用using块,它会自动关闭流,即使有异常:

using(Stream stream = File.Open(oFD.FileName, FileMode.Open))
{
    bF = new BinaryFormatter();

    sES = (SavedEventSet)bF.Deserialize(stream);
}

答案 1 :(得分:6)

在try块之前将stream设置为null。

在catch中检查stream是否为null,否则关闭流。

  SavedEventSet sES;
  OpenFileDialog oFD = new OpenFileDialog();
  Stream stream = null;
  BinaryFormatter bF;

  try
  {
    oFD.InitialDirectory = this.path;
    oFD.Title = "Open Event Saved File.";
    oFD.ShowDialog();

    if (oFD.FileName.Contains(".sav"))
    {
      stream = File.Open(oFD.FileName, FileMode.Open);
      bF = new BinaryFormatter();

      sES = (SavedEventSet)bF.Deserialize(stream);
      stream.Close();

    }
  }
  catch (Exception ex)
  {
    if (stream != null)
      stream.Close();
    /*handle Exception*/
  }

答案 2 :(得分:4)

使用finally块,这将执行是否发生异常:

try
{
  oFD.InitialDirectory = this.path;
  oFD.Title = "Open Event Saved File.";
  oFD.ShowDialog();

  if(oFD.FileName.Contains(".sav"))
  {
    stream = File.Open(oFD.FileName, FileMode.Open);
    bF = new BinaryFormatter();

    sES = (SavedEventSet)bF.Deserialize(stream);
  }
}
catch (Exception ex)
{
  /*handle Exception*/
}
finally
{
  if (stream != null)
    stream.Close();
}

答案 3 :(得分:0)

SavedEventSet sES; 
OpenFileDialog oFD = new OpenFileDialog(); 
BinaryFormatter bF; 

try 
{ 
    oFD.InitialDirectory = this.path; 
    oFD.Title = "Open Event Saved File."; 
    oFD.ShowDialog(); 

    if(oFD.FileName.Contains(".sav")) 
    { 
        using(Stream stream = File.Open(oFD.FileName, FileMode.Open))
        {
           bF = new BinaryFormatter(); 

           sES = (SavedEventSet)bF.Deserialize(stream); 
           stream.Close(); 
        }
    } 
} 
catch (Exception ex) 
{ 
    /*handle Exception*/ 
}