C# FileInfo.ReadLines方法代码示例

        public void ReadSpecificFileLines()
        {
            var file = Path.GetTempFileName();
            var info = new FileInfo(file);
            File.AppendAllLines(file, Enumerable.Range(1, 100).Select(i => i.ToString()));

            var lines = info.ReadLines(new[] { 1, 2, 3, 10, 100, 105 });

            lines.Select(l=>l.Number).ShouldAllBeEquivalentTo(new[] { 1, 2, 3, 10, 100 });

            File.Delete(file);
        }

        public void ReadLines()
        {
            // Type
            var @this = new FileInfo(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Examples_System_IO_FileInfo_ReadLines.txt"));

            // Intialization
            using (FileStream stream = @this.Create())
            {
                byte[] byteToWrites = Encoding.Default.GetBytes("Fizz" + Environment.NewLine + "Buzz");
                stream.Write(byteToWrites, 0, byteToWrites.Length);
            }

            // Examples
            List<string> result = @this.ReadLines().ToList(); // return new [] {"Fizz", "Buzz"};

            // Unit Test
            Assert.AreEqual("Fizz", result[0]);
            Assert.AreEqual("Buzz", result[1]);
        }

        public FileTailer(FileInfo file, 
            IObservable<string> textToMatch,
            IObservable<ScrollRequest> scrollRequest,
            IScheduler scheduler=null)
        {
            if (file == null) throw new ArgumentNullException(nameof(file));
            if (textToMatch == null) throw new ArgumentNullException(nameof(textToMatch));

            //create list of lines which contain the observable text
               var matchedLines = textToMatch
                    .Select(searchText =>
                    {
                        Func<string, bool> predicate = null;
                        if (!string.IsNullOrEmpty(searchText))
                            predicate = s => s.Contains(searchText, StringComparison.OrdinalIgnoreCase);

                        return file.WatchFile(scheduler:scheduler ?? Scheduler.Default)
                                    .TakeWhile(notification => notification.Exists)
                                    .Repeat()
                                    .ScanFile(predicate);

                    }).Switch()
                    .Replay(1).RefCount();

            MatchedLines = matchedLines.Select(x => x.MatchingLines.Length);

            TotalLines = matchedLines.Select(x => x.TotalLines);

            //todo: plug in file missing or error into the screen

            var lines = new SourceList<Line>();
            Lines = lines.AsObservableList();

            //this is the beast! Dynamically combine lines requested by the consumer
            //with the lines which exist in the file. This enables proper virtualisation of the file
            var scroller = matchedLines
                .CombineLatest(scrollRequest, (scanResult, request) => new {scanResult , request })
                .Subscribe(x =>
                {
                    var mode = x.request.Mode;
                    var pageSize = x.request.PageSize;
                    var endOfTail = x.scanResult.EndOfTail;
                    var isInitial = x.scanResult.Index==0;
                    var allLines = x.scanResult.MatchingLines;
                    var previousPage = lines.Items.Select(l => new LineIndex(l.Number, l.Index)).ToArray();

                    //Otherwise take the page size and start index from the request
                    var currentPage = (mode == ScrollingMode.Tail
                        ? allLines.Skip(allLines.Length-pageSize).Take(pageSize).ToArray()
                        : allLines.Skip(x.request.FirstIndex).Take(pageSize)).ToArray();

                    var added = currentPage.Except(previousPage).ToArray();
                    var removed = previousPage.Except(currentPage).Select(li=>li.Line).ToArray();

                    if (added.Length + removed.Length == 0) return;

                    try
                    {
                        var addedLines = file.ReadLines(added, (lineIndex, text) =>
                        {
                            var isEndOfTail = !isInitial && lineIndex.Line > endOfTail;
                            return new Line(lineIndex.Line, lineIndex.Index, text, isEndOfTail ? DateTime.Now : (DateTime?)null);
                        }).ToArray();

                        //get old lines from the current collection
                        var removedLines = lines.Items.Where(l => removed.Contains(l.Number)).ToArray();

                        //finally relect changes in the list
                        lines.Edit(innerList =>
                        {
                            innerList.RemoveMany(removedLines);
                            innerList.AddRange(addedLines);
                        });
                    }
                    catch (Exception)
                    {
                        //Very small chance of an error here but if one is causght the next successful read will recify this
                        //TODO: 1. Feedback to user that steaming has stopped
                        //TODO: 2. Place the ReadLines(..) method with the select of an observable
                    }

                });
            _cleanUp = new CompositeDisposable(Lines, scroller, lines);
        }

        public FileTailer(FileInfo file, 
            IObservable<string> textToMatch,
            IObservable<ScrollRequest> scrollRequest,
            IScheduler scheduler=null)
        {
            if (file == null) throw new ArgumentNullException(nameof(file));
            if (textToMatch == null) throw new ArgumentNullException(nameof(textToMatch));

            var lines = new SourceList<Line>();
            Lines = lines.AsObservableList();

            var locker = new object();
            scrollRequest = scrollRequest.Synchronize(locker);

            var metronome = Observable
                    .Interval(TimeSpan.FromMilliseconds(250), scheduler ?? Scheduler.Default)
                    .ToUnit()
                    .Replay().RefCount();

            //temp mess for a few days
            var indexer = file.WatchFile(metronome)
                            .TakeWhile(notification => notification.Exists)
                            .Repeat()
                            .Index()
                            .Synchronize(locker)
                            .Replay(1).RefCount();

            var matcher = textToMatch.Select(searchText =>
            {
                if (string.IsNullOrEmpty(searchText) || searchText.Length < 3)
                    return Observable.Return(LineMatches.None);

                return file.WatchFile(metronome)
                    .TakeWhile(notification => notification.Exists)
                    .Repeat()
                    .Match(s => s.Contains(searchText, StringComparison.OrdinalIgnoreCase));

            }).Switch()
            .Synchronize(locker)
            .Replay(1).RefCount();

            //count matching lines (all if no filter is specified)
            MatchedLines = indexer.CombineLatest(matcher, (indicies, matches) => matches == LineMatches.None ? indicies.Count : matches.Count);

            //count total line
            TotalLines = indexer.Select(x => x.Count);

            FileSize = file.WatchFile(metronome).Select(notification => notification.Size);

            var aggregator = indexer.CombineLatest(matcher, scrollRequest,(idx, mtch, scroll) => new CombinedResult(scroll, mtch, idx))
                .Select(result =>
                {
                    var scroll = result.Scroll;
                    var indicies = result.Incidies;
                    var matched = result.MatchedLines;

                    IEnumerable<LineIndex> indices;
                    if (result.MatchedLines.ChangedReason == LineMatchChangedReason.None)
                    {
                        indices = scroll.Mode == ScrollingMode.Tail
                            ? indicies.GetTail(scroll)
                            : indicies.GetFromIndex(scroll);
                    }
                    else
                    {
                        indices = scroll.Mode == ScrollingMode.Tail
                            ? indicies.GetTail(scroll, matched)
                            : indicies.GetFromIndex(scroll, matched);
                    }

                    var currentPage = indices.ToArray();
                    var previous = lines.Items.Select(l => l.LineIndex).ToArray();
                    var removed = previous.Except(currentPage).ToArray();
                    var removedLines = lines.Items.Where(l=> removed.Contains(l.LineIndex)).ToArray();

                    var added = currentPage.Except(previous).ToArray();
                    //finally we can load the line from the file
                    var newLines =  file.ReadLines(added, (lineIndex, text) =>
                    {
                        var isEndOfTail = indicies.ChangedReason != LinesChangedReason.Loaded && lineIndex.Line > indicies.TailStartsAt;

                        return new Line(lineIndex, text, isEndOfTail ? DateTime.Now : (DateTime?) null);
                    }, indicies.Encoding).ToArray();

                    return new { NewLines = newLines, OldLines = removedLines };
                })
                .RetryWithBackOff((Exception error, int attempts) =>
                {
                    //todo: plug in file missing or error into the screen
                    return TimeSpan.FromSeconds(1);
                 })
                 .Where(fn=> fn.NewLines.Length + fn.OldLines.Length > 0)
                .Subscribe(changes =>
                {
                    //update observable list
                    lines.Edit(innerList =>
                    {
                        if (changes.OldLines.Any()) innerList.RemoveMany(changes.OldLines);
                        if (changes.NewLines.Any())  innerList.AddRange(changes.NewLines);
                    });
//.........这里部分代码省略.........

        /// <summary>
        /// Fetch the files, and if requested, all the include files as well.
        /// </summary>
        /// <param name="ds"></param>
        /// <param name="extractionPath"></param>
        /// <returns></returns>
        private IEnumerable<FileInfo> GetSvnFiles(SvnTarget ds, PathInfo extractionPath)
        {
            // Build the location of this file to write out.
            var outfile = new FileInfo(Path.Combine(extractionPath.Path, ds.FileName));

            WriteVerbose($"Downloading svn file {ds.TargetName}");
            MCJobSVNHelpers.ExtractFile(ds, outfile);
            yield return outfile;

            // Next, we need to dip into all the levels down to see if we can't
            // figure out if there are includes.
            var includeFiles = outfile
                .ReadLines()
                .SelectMany(l => ExtractIncludedFiles(l, extractionPath));

            foreach (var l in includeFiles)
            {
                yield return l;
            }
        }

        public FileTailer(FileInfo file, 
            IObservable<string> textToMatch,
            IObservable<ScrollRequest> scrollRequest,
            IScheduler scheduler=null)
        {
            if (file == null) throw new ArgumentNullException(nameof(file));
            if (textToMatch == null) throw new ArgumentNullException(nameof(textToMatch));

            var lines = new SourceList<Line>();
            Lines = lines.AsObservableList();

            var matcher = textToMatch.Select(searchText =>
            {
                if (string.IsNullOrEmpty(searchText) || searchText.Length < 3)
                    return Observable.Return(LineMatches.None);

                return file.WatchFile(scheduler: scheduler)
                    .TakeWhile(notification => notification.Exists)
                    .Repeat()
                    .Match(s => s.Contains(searchText, StringComparison.OrdinalIgnoreCase));

            }).Switch()
            .Replay(1).RefCount();

            //temp mess for a few days
            var indexer = file.WatchFile(scheduler: scheduler)
                                .TakeWhile(notification => notification.Exists)
                                .Repeat()
                                .Index()
                                .Replay(1).RefCount();

            //count matching lines (all if no filter is specified)
            MatchedLines = indexer.CombineLatest(matcher, (indicies, matches) => matches == LineMatches.None ? indicies.Count : matches.Count);

            //count total line
            TotalLines = indexer.Select(x => x.Count);

            //todo: plug in file missing or error into the screen

            var locker = new object();
            var theBeast = indexer.Synchronize(locker)
                .CombineLatest(matcher.Synchronize(locker), scrollRequest.Synchronize(locker),(idx, mtch, scroll) => new CombinedResult(scroll, mtch, idx))
                .Select(result =>
                {
                    var scroll = result.Scroll;
                    var allLines = result.Incidies;
                    var matched = result.MatchedLines;

                    IEnumerable<LineIndex> indices;
                    if (result.MatchedLines.ChangedReason == LineMatchChangedReason.None)
                    {
                        indices = scroll.Mode == ScrollingMode.Tail
                            ? allLines.GetTail(scroll)
                            : allLines.GetFromIndex(scroll);
                    }
                    else
                    {
                        indices = scroll.Mode == ScrollingMode.Tail
                            ? allLines.GetTail(scroll, matched)
                            : allLines.GetFromIndex(scroll, matched);
                    }

                    return  file.ReadLines(indices, (lineIndex, text) =>
                    {
                        var isEndOfTail = allLines.ChangedReason != LinesChangedReason.Loaded && lineIndex.Line > allLines.TailStartsAt;
                        return new Line(lineIndex.Line, lineIndex.Index, text,isEndOfTail ? DateTime.Now : (DateTime?) null);
                    }).ToArray();
                })
                //.RetryWithBackOff((error, attempts) =>
                //{
                //    //TODO: Log
                //    return TimeSpan.FromSeconds(1);
                //})
                .Subscribe(newPage =>
                {
                    //update observable list
                    lines.Edit(innerList =>
                    {

                        var removed = innerList.Except(newPage).ToArray();
                        var added = newPage.Except(innerList).ToArray();

                        if (removed.Any()) innerList.RemoveMany(removed);
                        if (added.Any())  innerList.AddRange(added);
                    });

                });

            ////this is the beast! Dynamically combine lines requested by the consumer
            ////with the lines which exist in the file. This enables proper virtualisation of the file
            //var scroller = matchedLines
            //    .CombineLatest(scrollRequest, (scanResult, request) => new {scanResult , request })
            //    .Subscribe(x =>
            //    {
            //        var mode = x.request.Mode;
            //        var pageSize = x.request.PageSize;
            //        var endOfTail = x.scanResult.EndOfTail;
            //        var isInitial = x.scanResult.Index==0;
            //        var allLines = x.scanResult.MatchingLines;
            //        var previousPage = lines.Items.Select(l => new LineIndex(l.Number, l.Index, 0, 0)).ToArray();
//.........这里部分代码省略.........