按照加载巨大XML文件的进度

我尝试在dotnet（C＃，framework 3.5 SP1）中跟踪大型XML文件（我不是这些文件的提供者）的加载进度：通过网络文件共享从1 MB到300 MB。

我使用XmlReader进行加载而不是直接使用XmlDocument.Load方法来加速加载过程。

顺便说一句，我在互联网/文档上找不到如何遵循这个加载进度：似乎没有代表/事件存在。 有没有办法执行这项任务？ 具有用于XML保存目的的那种function可能是一件好事。

谢谢

Answer 1

假设您正在从流中读取这是一个（非完美的）如何执行的示例…基本上，ProgressStreamWrapper包装文件流并在Position更改时引发事件。

class Program { static void Main(string[] args) { Console.WriteLine("Reading big file..."); FileStream fileStream = File.OpenRead("c:\\temp\\bigfile.xml"); ProgressStreamWrapper progressStreamWrapper = new ProgressStreamWrapper(fileStream); progressStreamWrapper.PositionChanged += (o, ea) => Console.WriteLine((double) progressStreamWrapper.Position / progressStreamWrapper.Length * 100 + "% complete"); XmlReader xmlReader = XmlReader.Create(progressStreamWrapper); while (xmlReader.Read()) { //read the xml document } Console.WriteLine("DONE"); Console.ReadLine(); } } public class ProgressStreamWrapper : Stream, IDisposable { public ProgressStreamWrapper(Stream innerStream) { InnerStream = innerStream; } public Stream InnerStream { get; private set; } public override void Close() { InnerStream.Close(); } void IDisposable.Dispose() { base.Dispose(); InnerStream.Dispose(); } public override void Flush() { InnerStream.Flush(); } public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state) { return InnerStream.BeginRead(buffer, offset, count, callback, state); } public override int EndRead(IAsyncResult asyncResult) { int endRead = InnerStream.EndRead(asyncResult); OnPositionChanged(); return endRead; } public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state) { return InnerStream.BeginWrite(buffer, offset, count, callback, state); } public override void EndWrite(IAsyncResult asyncResult) { InnerStream.EndWrite(asyncResult); OnPositionChanged(); ; } public override long Seek(long offset, SeekOrigin origin) { long seek = InnerStream.Seek(offset, origin); OnPositionChanged(); return seek; } public override void SetLength(long value) { InnerStream.SetLength(value); } public override int Read(byte[] buffer, int offset, int count) { int read = InnerStream.Read(buffer, offset, count); OnPositionChanged(); return read; } public override int ReadByte() { int readByte = InnerStream.ReadByte(); OnPositionChanged(); return readByte; } public override void Write(byte[] buffer, int offset, int count) { InnerStream.Write(buffer, offset, count); OnPositionChanged(); } public override void WriteByte(byte value) { InnerStream.WriteByte(value); OnPositionChanged(); } public override bool CanRead { get { return InnerStream.CanRead; } } public override bool CanSeek { get { return InnerStream.CanSeek; } } public override bool CanTimeout { get { return InnerStream.CanTimeout; } } public override bool CanWrite { get { return InnerStream.CanWrite; } } public override long Length { get { return InnerStream.Length; } } public override long Position { get { return InnerStream.Position; } set { InnerStream.Position = value; OnPositionChanged(); } } public event EventHandler PositionChanged; protected virtual void OnPositionChanged() { if (PositionChanged != null) { PositionChanged(this, EventArgs.Empty); } } public override int ReadTimeout { get { return InnerStream.ReadTimeout; } set { InnerStream.ReadTimeout = value; } } public override int WriteTimeout { get { return InnerStream.WriteTimeout; } set { InnerStream.WriteTimeout = value; } } } 

Answer 2

内置装载机并不多; 但是，您可以编写拦截流 – 从此流加载文档，并通过事件公开Position ？ 即在Read方法中引发事件（间隔）？

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这是一个支持读写期间更新的示例：

 using System; using System.IO; using System.Xml; class ChattyStream : Stream { private Stream baseStream; public ChattyStream(Stream baseStream) { if (baseStream == null) throw new ArgumentNullException("baseStream"); this.baseStream = baseStream; updateInterval = 1000; } public event EventHandler ProgressChanged; protected virtual void OnProgressChanged() { var handler = ProgressChanged; if (handler != null) handler(this, EventArgs.Empty); } private void CheckDisposed() { if (baseStream == null) throw new ObjectDisposedException(GetType().Name); } protected Stream BaseStream { get { CheckDisposed(); return baseStream; } } int pos, updateInterval; public int UpdateInterval { get { return updateInterval; } set { if (value <= 0) throw new ArgumentOutOfRangeException("value"); updateInterval = value; } } protected void Increment(int value) { if (value > 0) { pos += value; if (pos >= updateInterval) { OnProgressChanged(); pos = pos % updateInterval; } } } public override int Read(byte[] buffer, int offset, int count) { int result = BaseStream.Read(buffer, offset, count); Increment(result); return result; } public override void Write(byte[] buffer, int offset, int count) { BaseStream.Write(buffer, offset, count); Increment(count); } public override void SetLength(long value) { BaseStream.SetLength(value); } public override void Flush() { BaseStream.Flush(); } public override long Position { get { return BaseStream.Position; } set { BaseStream.Position = value; } } public override long Seek(long offset, SeekOrigin origin) { return BaseStream.Seek(offset, origin); } public override long Length { get { return BaseStream.Length; } } public override bool CanWrite { get { return BaseStream.CanWrite; } } public override bool CanRead { get { return BaseStream.CanRead; } } public override bool CanSeek { get { return BaseStream.CanSeek; } } protected override void Dispose(bool disposing) { if (disposing && baseStream != null) { baseStream.Dispose(); } baseStream = null; base.Dispose(disposing); } public override void Close() { if (baseStream != null) baseStream.Close(); base.Close(); } public override int ReadByte() { int val = BaseStream.ReadByte(); if (val >= 0) Increment(1); return val; } public override void WriteByte(byte value) { BaseStream.WriteByte(value); Increment(1); } } static class Program { static void Main() { /* invent some big data */ const string path = "bigfile"; if (File.Exists(path)) File.Delete(path); using (var chatty = new ChattyStream(File.Create(path))) { chatty.ProgressChanged += delegate { Console.WriteLine("Writing: " + chatty.Position); }; using (var writer = XmlWriter.Create(chatty)) { writer.WriteStartDocument(); writer.WriteStartElement("xml"); for (int i = 0; i < 50000; i++) { writer.WriteElementString("add", i.ToString()); } writer.WriteEndElement(); writer.WriteEndDocument(); } chatty.Close(); } /* read it */ using (var chatty = new ChattyStream(File.OpenRead("bigfile"))) { chatty.ProgressChanged += delegate { Console.WriteLine("Reading: " + chatty.Position); }; // now read "chatty" with **any** API; XmlReader, XmlDocument, XDocument, etc XmlDocument doc = new XmlDocument(); doc.Load(chatty); } } } 

Answer 3

使用DataSet.Read（）怎么样？

要么，

 // Create the document. XmlDocument doc = new XmlDocument(); doc.Load(file); // Loop through all the nodes, and create the list of Product objects . List products = new List(); foreach (XmlElement element in doc.DocumentElement.ChildNodes) { Product newProduct = new Product(); newProduct.ID = Int32.Parse(element.GetAttribute("ID")); newProduct.Name = element.GetAttribute("Name"); // If there were more than one child node, you would probably use // another For Each loop here and move through the // Element.ChildNodes collection. newProduct.Price = Decimal.Parse(element.ChildNodes[0].InnerText); products.Add(newProduct); }