asp.net DZ论坛中根据IP地址取得所在地的代码

using System; 
using System.Data; 
using System.Configuration; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Web.UI.HtmlControls; 

//引入的命名空间 
using System.IO; 

/// <summary> 
/// 判断IP归属地类 
/// </summary> 
public class IpSearch 
{ 
private static object lockHelper = new object(); 

static PHCZIP pcz = new PHCZIP(); 

static string filePath = ""; 

static bool fileIsExsit = true; 

static IpSearch() 
{ 
filePath = HttpContext.Current.Server.MapPath("~/ipdata.config"); 
pcz.SetDbFilePath(filePath); 
} 

/// <summary> 
/// 返回IP查找结果 
/// </summary> 
/// <param name="IPValue">要查找的IP地址</param> 
/// <returns></returns> 
public static string GetAddressWithIP(string IPValue) 
{ 
lock (lockHelper) 
{ 
string result = pcz.GetAddressWithIP(IPValue.Trim()); 

if (fileIsExsit) 
{ 
if (result.IndexOf("IANA") >= 0) 
{ 
return ""; 
} 
else 
{ 
return result; 
} 
} 
else 
{ 
return null; 
} 
} 
} 

/// <summary> 
/// 辅助类，用于保存IP索引信息 
/// </summary> 
/// 
public class CZ_INDEX_INFO 
{ 
public UInt32 IpSet; 
public UInt32 IpEnd; 
public UInt32 Offset; 

public CZ_INDEX_INFO() 
{ 
IpSet = 0; 
IpEnd = 0; 
Offset = 0; 
} 
} 

//读取纯真IP数据库类 
public class PHCZIP 
{ 
protected bool bFilePathInitialized; 
protected string FilePath; 
protected FileStream FileStrm; 
protected UInt32 Index_Set; 
protected UInt32 Index_End; 
protected UInt32 Index_Count; 
protected UInt32 Search_Index_Set; 
protected UInt32 Search_Index_End; 
protected CZ_INDEX_INFO Search_Set; 
protected CZ_INDEX_INFO Search_Mid; 
protected CZ_INDEX_INFO Search_End; 

public PHCZIP() 
{ 
bFilePathInitialized = false; 
} 

public PHCZIP(string dbFilePath) 
{ 
bFilePathInitialized = false; 
SetDbFilePath(dbFilePath); 
} 

//使用二分法查找索引区，初始化查找区间 
public void Initialize() 
{ 
Search_Index_Set = 0; 
Search_Index_End = Index_Count - 1; 
} 

//关闭文件 
public void Dispose() 
{ 
if (bFilePathInitialized) 
{ 
bFilePathInitialized = false; 
FileStrm.Close(); 
//FileStrm.Dispose(); 
} 

} 
public bool SetDbFilePath(string dbFilePath) 
{ 
if (dbFilePath == "") 
{ 
return false; 
} 

try 
{ 
FileStrm = new FileStream(dbFilePath, FileMode.Open, FileAccess.Read, FileShare.Read); 
} 
catch 
{ 
return false; 
} 
//检查文件长度 
if (FileStrm.Length < 8) 
{ 
FileStrm.Close(); 
//FileStrm.Dispose(); 
return false; 
} 
//得到第一条索引的绝对偏移和最后一条索引的绝对偏移 
FileStrm.Seek(0, SeekOrigin.Begin); 
Index_Set = GetUInt32(); 
Index_End = GetUInt32(); 

//得到总索引条数 
Index_Count = (Index_End - Index_Set) / 7 + 1; 
bFilePathInitialized = true; 

return true; 

} 

public string GetAddressWithIP(string IPValue) 
{ 
if (!bFilePathInitialized) 
{ 
return ""; 
} 

Initialize(); 

UInt32 ip = IPToUInt32(IPValue); 

while (true) 
{ 

//首先初始化本轮查找的区间 

//区间头 
Search_Set = IndexInfoAtPos(Search_Index_Set); 
//区间尾 
Search_End = IndexInfoAtPos(Search_Index_End); 

//判断IP是否在区间头内 
if (ip >= Search_Set.IpSet && ip <= Search_Set.IpEnd) 
return ReadAddressInfoAtOffset(Search_Set.Offset); 
//判断IP是否在区间尾内 
if (ip >= Search_End.IpSet && ip <= Search_End.IpEnd) 
return ReadAddressInfoAtOffset(Search_End.Offset); 

//计算出区间中点 
Search_Mid = IndexInfoAtPos((Search_Index_End + Search_Index_Set) / 2); 

//判断IP是否在中点 
if (ip >= Search_Mid.IpSet && ip <= Search_Mid.IpEnd) 
return ReadAddressInfoAtOffset(Search_Mid.Offset); 

//本轮没有找到，准备下一轮 
if (ip < Search_Mid.IpSet) 
//IP比区间中点要小，将区间尾设为现在的中点，将区间缩小1倍。 
Search_Index_End = (Search_Index_End + Search_Index_Set) / 2; 
else 
//IP比区间中点要大，将区间头设为现在的中点，将区间缩小1倍。 
Search_Index_Set = (Search_Index_End + Search_Index_Set) / 2; 
} 

//return ""; 

} 

private string ReadAddressInfoAtOffset(UInt32 Offset) 
{ 
string country = ""; 
string area = ""; 
UInt32 country_Offset = 0; 
byte Tag = 0; 
//跳过4字节，因这4个字节是该索引的IP区间上限。 
FileStrm.Seek(Offset + 4, SeekOrigin.Begin); 

//读取一个字节，得到描述国家信息的“寻址方式” 
Tag = GetTag(); 

if (Tag == 0x01) 
{ 

//模式0x01，表示接下来的3个字节是表示偏移位置 
FileStrm.Seek(GetOffset(), SeekOrigin.Begin); 

//继续检查“寻址方式” 
Tag = GetTag(); 
if (Tag == 0x02) 
{ 
//模式0x02，表示接下来的3个字节代表国家信息的偏移位置 
//先将这个偏移位置保存起来，因为我们要读取它后面的地区信息。 
country_Offset = GetOffset(); 
//读取地区信息（注：按照Luma的说明，好像没有这么多种可能性，但在测试过程中好像有些情况没有考虑到， 
//所以写了个ReadArea()来读取。 
area = ReadArea(); 
//读取国家信息 
FileStrm.Seek(country_Offset, SeekOrigin.Begin); 
country = ReadString(); 
} 
else 
{ 
//这种模式说明接下来就是保存的国家和地区信息了，以'\0'代表结束。 
FileStrm.Seek(-1, SeekOrigin.Current); 
country = ReadString(); 
area = ReadArea(); 

} 
} 
else if (Tag == 0x02) 
{ 
//模式0x02，说明国家信息是一个偏移位置 
country_Offset = GetOffset(); 
//先读取地区信息 
area = ReadArea(); 
//读取国家信息 
FileStrm.Seek(country_Offset, SeekOrigin.Begin); 
country = ReadString(); 
} 
else 
{ 
//这种模式最简单了，直接读取国家和地区就OK了 
FileStrm.Seek(-1, SeekOrigin.Current); 
country = ReadString(); 
area = ReadArea(); 

} 
string Address = country + " " + area; 
return Address; 

} 

private UInt32 GetOffset() 
{ 
byte[] TempByte4 = new byte[4]; 
TempByte4[0] = (byte)FileStrm.ReadByte(); 
TempByte4[1] = (byte)FileStrm.ReadByte(); 
TempByte4[2] = (byte)FileStrm.ReadByte(); 
TempByte4[3] = 0; 
return BitConverter.ToUInt32(TempByte4, 0); 
} 

protected string ReadArea() 
{ 
byte Tag = GetTag(); 

if (Tag == 0x01 || Tag == 0x02) 
{ 
FileStrm.Seek(GetOffset(), SeekOrigin.Begin); 
return ReadString(); 
} 
else 
{ 
FileStrm.Seek(-1, SeekOrigin.Current); 
return ReadString(); 
} 
} 

protected string ReadString() 
{ 
UInt32 Offset = 0; 
byte[] TempByteArray = new byte[256]; 
TempByteArray[Offset] = (byte)FileStrm.ReadByte(); 
while (TempByteArray[Offset] != 0x00) 
{ 
Offset += 1; 
TempByteArray[Offset] = (byte)FileStrm.ReadByte(); 
} 
return System.Text.Encoding.Default.GetString(TempByteArray).TrimEnd('\0'); 
} 

protected byte GetTag() 
{ 
return (byte)FileStrm.ReadByte(); 
} 

protected CZ_INDEX_INFO IndexInfoAtPos(UInt32 Index_Pos) 
{ 
CZ_INDEX_INFO Index_Info = new CZ_INDEX_INFO(); 
//根据索引编号计算出在文件中在偏移位置 
FileStrm.Seek(Index_Set + 7 * Index_Pos, SeekOrigin.Begin); 
Index_Info.IpSet = GetUInt32(); 
Index_Info.Offset = GetOffset(); 
FileStrm.Seek(Index_Info.Offset, SeekOrigin.Begin); 
Index_Info.IpEnd = GetUInt32(); 

return Index_Info; 
} 

/// <summary> 
/// 从IP转换为Int32 
/// </summary> 
/// <param name="IpValue"></param> 
/// <returns></returns> 
public UInt32 IPToUInt32(string IpValue) 
{ 
string[] IpByte = IpValue.Split('.'); 
Int32 nUpperBound = IpByte.GetUpperBound(0); 
if (nUpperBound != 3) 
{ 
IpByte = new string[4]; 
for (Int32 i = 1; i <= 3 - nUpperBound; i++) 
IpByte[nUpperBound + i] = "0"; 
} 

byte[] TempByte4 = new byte[4]; 
for (Int32 i = 0; i <= 3; i++) 
{ 
//'如果是.Net 2.0可以支持TryParse。 
//'If Not (Byte.TryParse(IpByte(i), TempByte4(3 - i))) Then 
//' TempByte4(3 - i) = &H0 
//'End If 
if (IsNumeric(IpByte[i])) 
TempByte4[3 - i] = (byte)(Convert.ToInt32(IpByte[i]) & 0xff); 
} 

return BitConverter.ToUInt32(TempByte4, 0); 
} 

/// <summary> 
/// 判断是否为数字 
/// </summary> 
/// <param name="str">待判断字符串</param> 
/// <returns></returns> 
protected bool IsNumeric(string str) 
{ 
if (str != null && System.Text.RegularExpressions.Regex.IsMatch(str, @"^-?\d+$")) 
return true; 
else 
return false; 
} 

protected UInt32 GetUInt32() 
{ 
byte[] TempByte4 = new byte[4]; 
FileStrm.Read(TempByte4, 0, 4); 
return BitConverter.ToUInt32(TempByte4, 0); 
} 
} 

}