public static UserRow DeSerialize(byte[] bytes)
{
UserRow user = new UserRow();
user.id = BitConverter.ToInt32(bytes, 0);
user.username = Encoding.ASCII.GetString(bytes, 4, 32).Trim('\0');
user.email = Encoding.ASCII.GetString(bytes, 36, 255).Trim('\0');
return(user);
}
public static UserTable Open(string filePath)
{
var pager = Pager.PagerOpen(filePath);
UserTable table = new UserTable();
UserRow row = new UserRow();
table.Pager = pager;
table.MaxRowNumber = (int)pager.FileLength / row.RowSize;
return(table);
}
/// <summary>
/// 保存到磁盘
/// </summary>
public void Save()
{
UserRow userRow = new UserRow();
var pageNumber = MaxRowNumber / userRow.RowPerPage;
for (int i = 0; i < pageNumber; i++)
{
Pager.Flush(i, Pager.PageSize);
}
var additionRowsNumber = MaxRowNumber % userRow.RowPerPage;
if (additionRowsNumber > 0)
{
Pager.Flush(pageNumber, additionRowsNumber * userRow.RowSize);
}
}
public void Insert(UserRow row)
{
var tableMaxRows = Pager.TableMaxPages * row.RowPerPage;
if (MaxRowNumber >= tableMaxRows)
{
Console.WriteLine("Table Full");
return;
}
var bytes = row.Serialize();
Cursor cursor = Cursor.TableEnd(this);
cursor.CursorValue(out var page, out var offset);
Array.Copy(bytes, 0, page, offset, row.RowSize);
MaxRowNumber++;
}
public void Select()
{
UserRow userRow = new UserRow();
Console.WriteLine("Count:" + (MaxRowNumber));
Console.WriteLine("id\tusername\temail");
Cursor cursor = Cursor.TableStart(this);
while (!cursor.IsEndOfTable)
{
cursor.CursorValue(out var page, out var offset);
byte[] rowData = new byte[userRow.RowSize];
Array.Copy(page, offset, rowData, 0, userRow.RowSize);
var row = UserRow.DeSerialize(rowData);
Console.WriteLine($"{row.id}\t{row.username}\t{row.email}");
cursor.CursorAdvance();
}
}
