A leaf

        最近因为编程对二进制文件的读写，需要遍历所有字节，有把文件字节码转为文本进行操作的想法（即对16进制代码的可视化编辑，如UltraEdit等）。一直都担心速度问题而没有去尝试。在网上搜索了一下相关的内容，据说以下是把文件字节的16进制代码转换成字符串的比较快速的方法。

大概步骤是:
        将整个文件读成字节数组(对数组操作速度肯定比文件操作要快)；
        然后逐字节（数组每一元素）转换成表示16进制的字符串（这里用位运算，如果用系统函数那简直就是恶梦）；
        最后以返回合并后的字符串（不知文件太大了转换的字符串会不会影响操作？）。

static char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

public static string ToHexString(byte[] bytes) 
{
    char[] chars = new char[bytes.Length * 2];
    for (int i = 0; i < bytes.Length; i++) 
    {
        int b = bytes[i];
        chars[i * 2] = hexDigits[b >> 4];
        chars[i * 2 + 1] = hexDigits[b & 0xF];
    }
    return new string(chars);
}

目的是研究飞信聊天记录文件(SQLite数据库)的操作,顺便学习一下SQLite知识.

以下是摘自某网站文章的部分代码,可以看出SQLite数据库的一般操作和该数据库的大致结构关系: 

        string connString = "Data Source={0};Version=3;Password={1};";
        SQLiteConnection conn = null;
        SQLiteConnection connHis = null;
        string USERPROFILE = "";
        string folderURL=string.Empty; 

        private void btImport_Click(object sender, EventArgs e)
        {
            folderURL = USERPROFILE + @"\Application Data\Fetion\" + txtFetionId.Text;            try
            {
                conn = new SQLiteConnection(string.Format(connString, folderURL + "\\history.dat", txtFetionId.Text));
                connHis = new SQLiteConnection(string.Format(connString,txtImpPath.Text, txtFetionId.Text));                SQLiteDataAdapter sda = new SQLiteDataAdapter();
                DataSet ds = new DataSet();
                connHis.Open();

                sda.SelectCommand = new SQLiteCommand("select * from Player", connHis);
                sda.Fill(ds, "Player");
                sda.SelectCommand = new SQLiteCommand("select * from Message", connHis);
                sda.Fill(ds, "Message");
                sda.SelectCommand = new SQLiteCommand("select * from MessageBody", connHis);
                sda.Fill(ds, "MessageBody");
                sda.Dispose();
                connHis.Close();
                             conn.Open();
                SQLiteCommand cmd = new SQLiteCommand();
                cmd.Connection = conn;
                                   
                DbTransaction dt = conn.BeginTransaction();
                               
                                //向表内插入数据
                for (int n = 0; n < ds.Tables["

MessageBody"].Rows.Count; n++)
                {
                    DataRow dr = ds.Tables["MessageBody"].Rows[n];
                    cmd.CommandText = "INSERT OR IGNORE INTO [MessageBody] ([ID], [SenderUri], [SenderName], [Body], [Extend], [MessageType], [Time]) VALUES ($ID, $SenderUri, $SenderName, $Body, $Extend, $MessageType, $Time)";
                    cmd.Parameters.Add("$ID", DbType.String).Value = dr[0].ToString();
                    cmd.Parameters.Add("$SenderUri", DbType.String).Value = dr[1].ToString();
                    cmd.Parameters.Add("$SenderName", DbType.String).Value = dr[2].ToString();
                    cmd.Parameters.Add("$Body", DbType.String).Value = dr[3].ToString();
                    cmd.Parameters.Add("$Extend", DbType.String).Value = dr[4].ToString();
                    cmd.Parameters.Add("$MessageType", DbType.Int32).Value = int.Parse(dr[5].ToString());
                    cmd.Parameters.Add("$Time", DbType.Time).Value = DateTime.Parse( dr[6].ToString());
                    cmd.ExecuteNonQuery();
                }                for (int n = 0; n < ds.Tables["Message"].Rows.Count; n++)
                {
                    DataRow dr = ds.Tables["Message"].Rows[n];
                    cmd.CommandText = "INSERT OR IGNORE INTO [Message] ([MessageID], [ReceiverUri], [ReceiverName], [Status]) VALUES ($MessageID, $ReceiverUri, $ReceiverName, $Status)";
                    cmd.Parameters.Add("$MessageID", DbType.String).Value = dr[0].ToString();
                    cmd.Parameters.Add("$ReceiverUri", DbType.String).Value = dr[1].ToString();
                    cmd.Parameters.Add("$ReceiverName", DbType.String).Value = dr[2].ToString();
                    cmd.Parameters.Add("$Status", DbType.Int32).Value = int.Parse(dr[3].ToString());
                    // Console.WriteLine(cmd.CommandText);
                    cmd.ExecuteNonQuery();
                }                for (int n = 0; n < ds.Tables["

Player"].Rows.Count; n++)
                {
                    DataRow dr = ds.Tables["Player"].Rows[n];
                    cmd.CommandText = "INSERT OR IGNORE INTO [Player] ([Uri], [Name], [Type]) VALUES  ($Uri, $Name, $Type)";
                    cmd.Parameters.Add("$Uri", DbType.String).Value = dr[0].ToString();
                    cmd.Parameters.Add("$Name", DbType.String).Value = dr[1].ToString();
                    cmd.Parameters.Add("$Type", DbType.Int32).Value = int.Parse(dr[2].ToString());
                    // Console.WriteLine(cmd.CommandText);
                    cmd.ExecuteNonQuery();
                }                dt.Commit();

                conn.Close();
               
                rtbLog.Text += "记录导入成功！\n";            }
            catch (Exception ex)
            {
                rtbLog.Text += ex.Message + ‘\n‘;
                //throw;
            }
        }

(本文代码来源：http://www.dotnetthink.com)

飞信聊天记录存储路径:
 C:\Documents and Settings\%user%\Application Data\Fetion 下对应飞信号为文件夹的history.dat

该文件是SQLite数据库，密码为对应的飞信号。下面是存储数据库文件的表及视图的基本结构。

===========================================================
table：Player

CREATE TABLE Player(
Uri VARCHAR(256) PRIMARY KEY,
Name VARCHAR(256),
Type INTEGER)

===========================================================
table:MessageBody

CREATE TABLE MessageBody(
ID VARCHAR(64) PRIMARY KEY,
SenderUri VARCHAR(256),
SenderName VARCHAR(256),
Body VARCHAR(1000),
Extend VARCHAR(1000),
MessageType INTEGER,
Time DATETIME)

============================================================
table:Message

CREATE TABLE Message(
MessageID VARCHAR(64),
ReceiverUri VARCHAR(256),
ReceiverName VARCHAR(256),
STATUS INTEGER,
PRIMARY KEY (MessageID, ReceiverUri))

============================================================
view:vMessage

CREATE VIEW vMessage AS
SELECT MessageBody.ID AS ID, MessageBody.SenderUri AS SenderUri , MessageBody.SenderName AS SenderName , Message.ReceiverUri AS ReceiverUri , Message.ReceiverName AS ReceiverName , MessageBody.Body AS Body , MessageBody.Extend AS Extend,
MessageBody.MessageType AS MessageType , Message.STATUS AS STATUS , MessageBody.[Time] AS [Time] , P2.[Type] AS SenderType , P1.[Type] AS ReceiverType
FROM Message INNER JOIN
MessageBody ON Message.MessageID = MessageBody.ID
INNER JOIN Player P1 ON Message.ReceiverUri = P1.Uri
INNER JOIN Player P2 ON MessageBody.SenderUri = P2.Uri

============================================================ 
view:vPlayerRef

CREATE VIEW vPlayerRef AS
SELECT COUNT(MessageBody.SenderUri) + COUNT(Message.ReceiverUri) AS RefCount, Player.Uri AS Uri
FROM Player LEFT OUTER JOIN MessageBody ON Player.Uri = MessageBody.SenderUri LEFT OUTER JOIN Message ON Player.Uri = Message.ReceiverUri
GROUP BY Player.Uri

============================================================

 这样就可以对该数据库进行读写操作，实现对聊天记录的查看、导出、导入等功能了！

 (本文资料来源：http://www.dotnetthink.com)