C#中的各种流

//Stream是一个抽象类，不能直接实例化

//FileStream继承于Stream ,读写文件流

//StreamWriter继承于TextWriter(抽象类，继承于MarshalByRefObject, IDisposable)，可以操作Stream

//StreamReader继承于TextReader(抽象类，继承于MarshalByRefObject, IDisposable)，可以操作Stream

//MemoryStream继承于Stream

//BufferedStream继承于Stream

StreamWriter和StreamReader可以直接操作文件进行读写，但前提是文件是已经存在的，如果没有文件存在，会抛出异常。

//文件流操作

private void btnFileStream_Click(object sender, EventArgs e)

{

string path=@"c:\test.txt";

#region FileStream 读写文件必须以字节形式

//向文件中写入流

using (FileStream fs = File.Create(path))

{

//byte[] info = new UTF8Encoding(true).GetBytes("this is some text");

Byte[] info = Encoding.GetEncoding("UTF-8").GetBytes("this is some text");

fs.Write(info, 0, info.Length);

}

//打开文件读回流

using (FileStream fs = File.OpenRead(path))

{

string result = string.Empty;

byte[] info = new byte[1024];

//UTF8Encoding temp = new UTF8Encoding(true);

while (fs.Read(info, 0, info.Length) > 0)

{

//result += temp.GetString(info);

result += Encoding.GetEncoding("UTF-8").GetString(info);

}

System.Diagnostics.Debug.WriteLine(result);

}

#endregion

#region StreamWriter 以字符的形式写入 1.可以往Stream里写，2.也可以直接往路径文件里写信息(前提是文件已存在)

//打开文件，在文件末尾附加信息

FileStream fileStream = new FileStream(path,FileMode.Append);

StreamWriter sw = new StreamWriter(fileStream);

sw.WriteLine("This is the appended line.");

sw.Close();

fileStream.Close();

//打开文件，在文件末尾附加信息

using (FileStream file = new FileStream(path, FileMode.Append))

{

using (StreamWriter writer = new StreamWriter(file))

//using (StreamWriter writer = new StreamWriter(path))

{

writer.WriteLine("this a the second appended line.");

writer.Write("this a the third appended line.");

}

}

//如果文件已经存在，可以及直接用StreamWriter写入，不用File

//using (StreamWriter writer = new StreamWriter(path))

// {

// writer.WriteLine("this a the second appended line.");

// writer.Write("this a the third appended line.");

// }

#endregion

#region StreamReader 1.可以从Stream里读，2.也可以直接从文件里读信息

//读取文件文本内容 1

using (StreamReader reader = new StreamReader(path,Encoding.UTF8))

{

string line;

while ((line = reader.ReadLine()) != null)

{

System.Diagnostics.Debug.WriteLine(line);

}

}

//读取文件文本内容 2

using(FileStream fs1=File.OpenRead(path))

{

using (StreamReader reader = new StreamReader(fs1,Encoding.GetEncoding("GB2312")))

{

string result = reader.ReadToEnd();

System.Diagnostics.Debug.WriteLine(result);

}

}

#endregion

#region 内存流，可读可写，操作单位是字节，主要作用是在内存中操作字节流，最后可写入到Stream中

using (MemoryStream ms = new MemoryStream())

{

UnicodeEncoding uniEncoding = new UnicodeEncoding();

byte[] info = uniEncoding.GetBytes(" this is MemoryStream");

//把信息写入到MemoryStream中

ms.Write(info, 0, info.Length);

byte[] result=new byte[ms.Length];

//从流中读取信息到字节数组中

ms.Read(result, 0, info.Length);

using (Stream s = new FileStream("c:/aa.txt",FileMode.Create))

{

//可以将内存流写入到Stream中：this is MemoryStream

ms.WriteTo(s);

}

}

#endregion

//缓冲区是内存中的字节块，用于缓存数据，从而减少对操作系统的调用次数。 缓冲区可提高读取和写入性能。

//BufferedStream

}

写日志：

SaveFileDialog saveFileDialog = new SaveFileDialog();

saveFileDialog.Filter = "log files(*.log)|*.log|txt files(*.txt)|*.txt|All files(*.*)|*.*";

saveFileDialog.FilterIndex = 0;

saveFileDialog.RestoreDirectory = true;

saveFileDialog.FileName = DateTime.Now.ToString("yyyyMMddHHmmss") + ".log";

FileStream fs = null;

StreamWriter sw = null;

if (saveFileDialog.ShowDialog() == DialogResult.OK)

{

try

{

fs = (FileStream)saveFileDialog.OpenFile();

sw = new StreamWriter(fs);

sw.Write(txtImportLog.Text);

}

catch (Exception ex)

{

MessageBox.Show("日志导出失败!" + ex.Message);

}

finally

{

sw.Flush();

sw.Close();

fs.Close();

}

}