public string GetAddressWithIp(string ipValue)
{
if (!_bFilePathInitialized)
{
return("");
}
Initialize();
var ip = IptoUInt32(ipValue);
while (true)
{
//首先初始化本轮查找的区间
//区间头
_searchSet = IndexInfoAtPos(SearchIndexSet);
//区间尾
_searchEnd = IndexInfoAtPos(SearchIndexEnd);
//判断IP是否在区间头内
if (ip >= _searchSet.IpSet && ip <= _searchSet.IpEnd)
{
return(ReadAddressInfoAtOffset(_searchSet.Offset));
}
//判断IP是否在区间尾内
if (ip >= _searchEnd.IpSet && ip <= _searchEnd.IpEnd)
{
return(ReadAddressInfoAtOffset(_searchEnd.Offset));
}
//计算出区间中点
_searchMid = IndexInfoAtPos((SearchIndexEnd + SearchIndexSet) / 2);
//判断IP是否在中点
if (ip >= _searchMid.IpSet && ip <= _searchMid.IpEnd)
{
return(ReadAddressInfoAtOffset(_searchMid.Offset));
}
//本轮没有找到，准备下一轮
if (ip < _searchMid.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。
SearchIndexEnd = (SearchIndexEnd + SearchIndexSet) / 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。
SearchIndexSet = (SearchIndexEnd + SearchIndexSet) / 2;
}
}
//return "";
}
private CzIndexInfo IndexInfoAtPos(UInt32 indexPos)
{
var indexInfo = new CzIndexInfo();
//根据索引编号计算出在文件中在偏移位置
FileStrm.Seek(IndexSet + 7 * indexPos, SeekOrigin.Begin);
indexInfo.IpSet = GetUInt32();
indexInfo.Offset = GetOffset();
FileStrm.Seek(indexInfo.Offset, SeekOrigin.Begin);
indexInfo.IpEnd = GetUInt32();
return(indexInfo);
}