C#中的各种流

红太狼 2022-08-06 11:30 513阅读 0赞

//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][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();  
                \}  
            \}

[path_c_test.txt]: mailto:path=@'%20rel=