跟踪一个StreamReader的线的位置(Tracking the position of the

嗨，大家好我需要做的就是跟踪我从流读取器读取线的位置，当我说reader.ReadLine()我需要知道该行的文件中的位置，我也希望能够然后读取从我以前跟踪的位置文件。

这可能吗？ 如果是这样，请协助。

帮助是非常赞赏

提前致谢。

Answer 1:

你可以做的三种方式这一个：

1）写自己的StreamReader。 这里有一个良好的开端： 如何知道一个文本文件一个StreamReader的位置（行号）？

2）StreamReader类有两个非常重要的，但私有变量称为charPos和charLen中所需的定位实际的“读”的位置，而不仅仅是流的基本位置。 你可以使用反射来获取值的建议在这里

 Int32 charpos = (Int32) s.GetType().InvokeMember("charPos", BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.GetField ,null, s, null); Int32 charlen= (Int32) s.GetType().InvokeMember("charLen", BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.GetField ,null, s, null); return (Int32)s.BaseStream.Position-charlen+charpos; 

3）简单地读取整个文件转换成字符串数组。 事情是这样的：

 char[] CRLF = new char[2] { '\n', '\r' }; TextReader tr = File.OpenText("some path to file"); string[] fileLines = tr.ReadToEnd().Split(CRLF); 

另一种可能性（沿SAMES线作为＃3）处于所述行读取和存储线在阵列中。 当你想阅读之前的线，需要使用数组。

Answer 2:

也许这可以帮助你

  public class StreamLineReader : IDisposable
    {
        const int BufferLength = 1024;

        Stream _Base;
        int _Read = 0, _Index = 0;
        byte[] _Bff = new byte[BufferLength];

        long _CurrentPosition = 0;
        int _CurrentLine = 0;

        /// <summary>
        /// CurrentLine number
        /// </summary>
        public long CurrentPosition { get { return _CurrentPosition; } }
        /// <summary>
        /// CurrentLine number
        /// </summary>
        public int CurrentLine { get { return _CurrentLine; } }
        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="stream">Stream</param>
        public StreamLineReader(Stream stream) { _Base = stream; }
        /// <summary>
        /// Count lines and goto line number
        /// </summary>
        /// <param name="goToLine">Goto Line number</param>
        /// <returns>Return true if goTo sucessfully</returns>
        public bool GoToLine(int goToLine) { return IGetCount(goToLine, true) == goToLine; }
        /// <summary>
        /// Count lines and goto line number
        /// </summary>
        /// <param name="goToLine">Goto Line number</param>
        /// <returns>Return the Count of lines</returns>
        public int GetCount(int goToLine) { return IGetCount(goToLine, false); }
        /// <summary>
        /// Internal method for goto&Count
        /// </summary>
        /// <param name="goToLine">Goto Line number</param>
        /// <param name="stopWhenLine">Stop when found the selected line number</param>
        /// <returns>Return the Count of lines</returns>
        int IGetCount(int goToLine, bool stopWhenLine)
        {
            _Base.Seek(0, SeekOrigin.Begin);
            _CurrentPosition = 0;
            _CurrentLine = 0;
            _Index = 0;
            _Read = 0;

            long savePosition = _Base.Length;

            do
            {
                if (_CurrentLine == goToLine)
                {
                    savePosition = _CurrentPosition;
                    if (stopWhenLine) return _CurrentLine;
                }
            }
            while (ReadLine() != null);

            // GoToPosition

            int count = _CurrentLine;

            _CurrentLine = goToLine;
            _Base.Seek(savePosition, SeekOrigin.Begin);

            return count;
        }
        /// <summary>
        /// Read Line
        /// </summary>
        /// <returns></returns>
        public string ReadLine()
        {
            bool found = false;

            StringBuilder sb = new StringBuilder();
            while (!found)
            {
                if (_Read <= 0)
                {
                    // Read next block
                    _Index = 0;
                    _Read = _Base.Read(_Bff, 0, BufferLength);
                    if (_Read == 0)
                    {
                        if (sb.Length > 0) break;
                        return null;
                    }
                }

                for (int max = _Index + _Read; _Index < max; )
                {
                    char ch = (char)_Bff[_Index];
                    _Read--; _Index++;
                    _CurrentPosition++;

                    if (ch == '\0' || ch == '\n')
                    {
                        found = true;
                        break;
                    }
                    else if (ch == '\r') continue;
                    else sb.Append(ch);
                }
            }

            _CurrentLine++;
            return sb.ToString();
        }
        /// <summary>
        /// Free resources
        /// </summary>
        public void Dispose()
        {
            if (_Base != null)
            {
                _Base.Close();
                _Base.Dispose();
                _Base = null;
            }
        }
    }

使用：

 using (StreamLineReader st = new StreamLineReader(File.OpenRead("E:\\log.txt")))
        {
            bool ok = st.GoToLine(1);
            int count= st.GetCount(0);

            string w0 = st.ReadLine();
            string w1 = st.ReadLine();
            string w2 = st.ReadLine();
            string w3 = st.ReadLine();
        }

文章来源: Tracking the position of the line of a streamreader