C#文件操作

1、FileStream只处理原始字节，不处理字符，使用StreamRead和StreamWrite处理字符。

　　1）使用FileStream处理字符串时，须经过中间类的转换：

            byte[] byData = new byte[200];
            char[] charData = new Char[200];
            //Byte2Char
            Decoder d = Encoding.UTF8.GetDecoder();
            d.GetChars(byData, 0, byData.Length, charData, 0);   
             //Char2Byte
            Encoder e = Encoding.UTF8.GetEncoder();
            e.GetBytes(charData, 0, charData.Length, byData, 0, true);        

　　2）StreamRead的使用：

               FileStream aFile = new FileStream("Log.txt", FileMode.Open);
                StreamReader sr = new StreamReader(aFile);
                line = sr.ReadLine();
                // Read data in line by line.
                while (line != null)
                {
                    Console.WriteLine(line);
                    line = sr.ReadLine();
                }
                sr.Close();            

　　3）StreamWrite的使用：

             FileStream aFile = new FileStream("Log.txt", FileMode.OpenOrCreate);
                StreamWriter sw = new StreamWriter(aFile);
                sw.WriteLine("now： {0} ",DateTime.Now.ToLongDateString());
                sw.Close();            

 2、读取分隔符文件

 using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace CommaValues
{
    class Program
    {
        private static List<Dictionary<string, string>> GetData(
   out List<string> columns)
        {
            string line;
            string[] stringArray;
            char[] charArray = new char[] { ',' };
            List<Dictionary<string, string>> data =
               new List<Dictionary<string, string>>();
            columns = new List<string>();

            try
            {
                FileStream aFile = new FileStream(@"....SomeData.txt", FileMode.Open);
                StreamReader sr = new StreamReader(aFile);

                // Obtain the columns from the first line.
                // Split row of data into string array
                line = sr.ReadLine();
                stringArray = line.Split(charArray);

                for (int x = 0; x <= stringArray.GetUpperBound(0); x++)    //GetUpperBound:获取 System.Array 的指定维度的上限。 
                {
                    columns.Add(stringArray[x]);
                }

                line = sr.ReadLine();
                while (line != null)
                {
                    // Split row of data into string array
                    stringArray = line.Split(charArray);
                    Dictionary<string, string> dataRow = new Dictionary<string, string>();

                    for (int x = 0; x <= stringArray.GetUpperBound(0); x++)
                    {
                        dataRow.Add(columns[x], stringArray[x]);
                    }

                    data.Add(dataRow);

                    line = sr.ReadLine();
                }

                sr.Close();
                return data;
            }
            catch (IOException ex)
            {
                Console.WriteLine("An IO exception has been thrown!");
                Console.WriteLine(ex.ToString());
                Console.ReadLine();
                return data;
            }
        }

        static void Main(string[] args)
        {
            List<string> columns;
            List<Dictionary<string, string>> myData = GetData(out columns);

            foreach (string column in columns)
            {
                Console.Write("{0,-20}", column);
            }
            Console.WriteLine();

            foreach (Dictionary<string, string> row in myData)
            {
                foreach (string column in columns)
                {
                    Console.Write("{0,-20}", row[column]);
                }
                Console.WriteLine();
            }
            Console.ReadKey();
        }
    }
}

3、处理压缩|解压文件

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.IO.Compression;

namespace Compressor
{
    class Program
    {
        static void SaveCompressedFile(string filename, string data)
        {
            FileStream fileStream =
               new FileStream(filename, FileMode.Create, FileAccess.Write);
            GZipStream compressionStream =
               new GZipStream(fileStream, CompressionMode.Compress);
            StreamWriter writer = new StreamWriter(compressionStream);
            writer.Write(data);
            writer.Close();
        }

        static string LoadCompressedFile(string filename)
        {
            FileStream fileStream =
               new FileStream(filename, FileMode.Open, FileAccess.Read);
            GZipStream compressionStream =
               new GZipStream(fileStream, CompressionMode.Decompress);
            StreamReader reader = new StreamReader(compressionStream);
            string data = reader.ReadToEnd();
            reader.Close();
            return data;
        }

        static void Main(string[] args)
        {
            try
            {
                string filename = "compressedFile.txt";

                Console.WriteLine(
                   "Enter a string to compress (will be repeated 100 times):");
                string sourceString = Console.ReadLine();
                StringBuilder sourceStringMultiplier =
                   new StringBuilder(sourceString.Length * 100);
                for (int i = 0; i < 100; i++)
                {
                    sourceStringMultiplier.Append(sourceString);
                }
                sourceString = sourceStringMultiplier.ToString();
                Console.WriteLine("Source data is {0} bytes long.", sourceString.Length);

                SaveCompressedFile(filename, sourceString);
                Console.WriteLine("
Data saved to {0}.", filename);

                FileInfo compressedFileData = new FileInfo(filename);
                Console.WriteLine("Compressed file is {0} bytes long.",
                                  compressedFileData.Length);

                string recoveredString = LoadCompressedFile(filename);
                recoveredString = recoveredString.Substring(
                   0, recoveredString.Length / 100);
                Console.WriteLine("
Recovered data: {0}", recoveredString);

                Console.ReadKey();
            }
            catch (IOException ex)
            {
                Console.WriteLine("An IO exception has been thrown!");
                Console.WriteLine(ex.ToString());
                Console.ReadKey();
            }
        }
    }
}

 4、序列化|反序列化（IFormatter） ：类默认是不允许序列化的，要进行序列化必须给类添加 [Serializable]属性，不想序列化特殊字段可以添加 [NonSerialized]属性

　　1）System.Runtime.Serialization.Formatters.Binary下BinaryFormatter类把二进制数据序列化为对象。

// Get serializer.
                IFormatter serializer = new BinaryFormatter();

                // Serialize products.
                FileStream saveFile =
                  new FileStream("Products.bin", FileMode.Create, FileAccess.Write);
                serializer.Serialize(saveFile, products);
                saveFile.Close();

                // Deserialize products.
                FileStream loadFile =
                  new FileStream("Products.bin", FileMode.Open, FileAccess.Read);
                List<Product> savedProducts =
                   serializer.Deserialize(loadFile) as List<Product>;
                loadFile.Close();

　　2）System.Runtime.Serialization.Formatters.Soap下SoapFormatter类把Soap格式的XML数据序列化为对象。(需要给工程中的引用，添加引用中选择“程序集”，找到它并添加)

　　3)System.Web.UI下ObjectStateFormatter类用于在ASP.Net中序列化viewState。

　　4）NetDataConstractSerializer类用于序列化WCF数据合同。

5、监控文件（FileSystemWatcher）

　　1)设置完属性和事件之后，将EnableRaisingEvents属性设置为True，就可以开始监控操作。

　　定义文件监视器：   

 private FileSystemWatcher watcher;

　　定义显示监视器提示内容的委托和异步调用的函数

 private delegate void UpdateWatchTextDelegate(string newText);
      public void UpdateWatchText(string newText)
      {
      }

　　设置属性：

    {
          watcher.Path = Path.GetDirectoryName(txtLocation.Text);
          watcher.Filter = Path.GetFileName(txtLocation.Text);
          watcher.NotifyFilter = NotifyFilters.LastWrite |
             NotifyFilters.FileName | NotifyFilters.Size;
          // Begin watching.
          watcher.EnableRaisingEvents = true;
      }

　　设置事件

            this.watcher = new FileSystemWatcher();
            this.watcher.Deleted +=
               new FileSystemEventHandler(this.OnDelete);
            this.watcher.Renamed +=
               new RenamedEventHandler(this.OnRenamed);
            this.watcher.Changed +=
               new FileSystemEventHandler(this.OnChanged);
            this.watcher.Created +=
               new FileSystemEventHandler(this.OnCreate);        

　　定义触发的相应事件：

      // Define the event handlers.
      public void OnChanged(object source, FileSystemEventArgs e)
      {
         try
         {
            StreamWriter sw =
               new StreamWriter("C:/FileLogs/Log.txt", true);
            sw.WriteLine("File: {0} {1}", e.FullPath,
                         e.ChangeType.ToString());
            sw.Close();
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),      //在创建控件的基础句柄所在线程上，用指定的参数异步执行指定委托。
               "Wrote change event to log");
         }
         catch (IOException)
         {
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Error Writing to log");
         }
      }

      public void OnRenamed(object source, RenamedEventArgs e)
      {
         try
         {
            StreamWriter sw =
               new StreamWriter("C:/FileLogs/Log.txt", true);
            sw.WriteLine("File renamed from {0} to {1}", e.OldName,
                         e.FullPath);
            sw.Close();
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Wrote renamed event to log");
         }
         catch (IOException)
         {
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Error Writing to log");
         }
      }

      public void OnDelete(object source, FileSystemEventArgs e)
      {
         try
         {
            StreamWriter sw =
               new StreamWriter("C:/FileLogs/Log.txt", true);
            sw.WriteLine("File: {0} Deleted", e.FullPath);
            sw.Close();
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Wrote delete event to log");
         }
         catch (IOException)
         {
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Error Writing to log");
         }
      }

      public void OnCreate(object source, FileSystemEventArgs e)
      {
         try
         {
            StreamWriter sw =
               new StreamWriter("C:/FileLogs/Log.txt", true);
            sw.WriteLine("File: {0} Created", e.FullPath);
            sw.Close();
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Wrote create event to log");
         }
         catch (IOException)
         {
            this.BeginInvoke(new UpdateWatchTextDelegate(UpdateWatchText),
               "Error Writing to log");
         }
      }