using System; 
using System.Collections.Generic; 
using System.Collections; 

public class MyClass 
{ 
public static void Main() 
{ 
long vTickCount = Environment.TickCount; 
Hashtable hash = init(); 
WL("用时：{0}毫秒", Environment.TickCount-vTickCount); 

//写入文件 
vTickCount = Environment.TickCount; 
WriteFile("e:/hash.dat"); 
WL("用时：{0}毫秒", Environment.TickCount-vTickCount); 

//从文件中读取，恢复Hash结构 
vTickCount = Environment.TickCount; 
hash = ReadFile("e:/hash.dat"); 
WL("用时：{0}毫秒", Environment.TickCount-vTickCount); 

RL(); 
} 

public static void WriteFile(string file) 
{ 
//自由发挥 
} 

public static Hashtable ReadFile(string file) 
{ 
//自由发挥 
return null; 
} 

public static Hashtable init() 
{ 
Hashtable hash = new Hashtable(); 
for(int i=0;i <4000000;i++) 
{ 
hash.Add(Guid.NewGuid().ToString(), i); 
} 
WL("完成"); 
return hash; 
} 

#region Helper methods 

private static void WL(object text, params object[] args) 
{ 
Console.WriteLine(text.ToString(), args); 
} 

private static void RL() 
{ 
Console.ReadLine(); 
} 

private static void Break()  
{ 
System.Diagnostics.Debugger.Break(); 
} 

#endregion 
}

using System.Runtime.InteropServices; 

[DllImport("kernel32.dll")] 
public static extern IntPtr CreateFileMapping(IntPtr hFile, 
IntPtr lpFileMappingAttributes, uint flProtect, 
uint dwMaximumSizeHigh, 
uint dwMaximumSizeLow, string lpName); 

[DllImport("kernel32.dll")] 
public static extern IntPtr MapViewOfFile(IntPtr hFileMappingObject, uint 
dwDesiredAccess, uint dwFileOffsetHigh, uint dwFileOffsetLow, 
IntPtr dwNumberOfBytesToMap); 

[DllImport("kernel32.dll")] 
public static extern bool UnmapViewOfFile(IntPtr lpBaseAddress); 

[DllImport("kernel32.dll")] 
public static extern bool CloseHandle(IntPtr hObject); 

[DllImport("kernel32.dll")] 
public static extern IntPtr CreateFile(string lpFileName, 
int dwDesiredAccess, FileShare dwShareMode, IntPtr securityAttrs, 
FileMode dwCreationDisposition, int dwFlagsAndAttributes, IntPtr hTemplateFile); 

[DllImport("kernel32.dll")] 
public static extern uint GetFileSize(IntPtr hFile, IntPtr lpFileSizeHigh); 

public const int GENERIC_READ = -2147483648; //0x80000000 
public const int GENERIC_WRITE = 0x40000000; 
public const int GENERIC_EXECUTE = 0x20000000; 
public const int GENERIC_ALL = 0x10000000; 
public const int FILE_ATTRIBUTE_NORMAL = 0x80; 
public const int FILE_FLAG_SEQUENTIAL_SCAN = 0x8000000; 
public const int INVALID_HANDLE_VALUE = -1; 

public const int PAGE_NOACCESS = 1; 
public const int PAGE_READONLY = 2; 
public const int PAGE_READWRITE = 4; 

public const int FILE_MAP_COPY = 1; 
public const int FILE_MAP_WRITE = 2; 
public const int FILE_MAP_READ = 4; 


private void button1_Click(object sender, EventArgs e) 
{ 
IntPtr vFileHandle = CreateFile(@"c:\temp\temp.txt", 
GENERIC_READ | GENERIC_WRITE, FileShare.Read | FileShare.Write, 
IntPtr.Zero, FileMode.Open, 
FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, IntPtr.Zero); 
if (INVALID_HANDLE_VALUE != (int)vFileHandle) 
{ 
IntPtr vMappingHandle = CreateFileMapping( 
vFileHandle, IntPtr.Zero, PAGE_READWRITE, 0, 0, "~MappingTemp"); 
if (vMappingHandle != IntPtr.Zero) 
{ 
IntPtr vHead = MapViewOfFile(vMappingHandle, 
FILE_MAP_COPY | FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, IntPtr.Zero); 
if (vHead != IntPtr.Zero) 
{ 
uint vSize = GetFileSize(vFileHandle, IntPtr.Zero); 
for (int i = 0; i <= vSize / 2; i++) 
{ 
byte vTemp = Marshal.ReadByte((IntPtr)((int)vHead + i)); 
Marshal.WriteByte((IntPtr)((int)vHead + i), 
Marshal.ReadByte((IntPtr)((int)vHead + vSize - i - 1))); 
Marshal.WriteByte((IntPtr)((int)vHead + vSize - i - 1), vTemp); 
} 
UnmapViewOfFile(vHead); 
} 
CloseHandle(vMappingHandle); 
} 
CloseHandle(vFileHandle); 
} 
}