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标题: asp. net下使用foreach简化文本文件的访问。 [打印本页]

作者: ‘為ㄋ袮 时间: 2009-3-16 23:10
标题: asp. net下使用foreach简化文本文件的访问。
很多时候，我们总是按照行的方式访问文本文件，使用foreach语句能够极大地简化访问逻辑：例如：
foreach (string line in new LineReader(”c:\abc.txt”))
  Console.WriteLine(line);
完整代码如下：
using System;
using System.IO;
using System.Text;
using System.Collections;
namespace Forks.Utils.IO
{
public struct LineReader : IDisposable
{
public LineReader(string file, Encoding encoding) : this(file, encoding, false)
      {

}
public LineReader(string file, Encoding encoding, bool ignoreBlankLines) : this(new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read), encoding, ignoreBlankLines)
{
}
public LineReader(Stream stream, Encoding encoding) : this(stream, encoding, false)
{
}
public LineReader(Stream stream, Encoding encoding, bool ignoreBlankLines) : this(new StreamReader(stream, encoding), ignoreBlankLines)
{
}
public LineReader(TextReader reader) : this(reader, false)
{
}
TextReader mReader;
bool mIgnoreBlankLines;
public LineReader(TextReader reader, bool ignoreBlankLines)
{
   mReader = reader;
   mIgnoreBlankLines = ignoreBlankLines;
   mCurrent = null;
}
public LineReader GetEnumerator()
{
   return this;
}
public void Reset()
{
   throw new NotSupportedException("LineReader???ü?áè?ò?′?");
}
string mCurrent;
public string Current
{
   get
   {
      return mCurrent;
   }
}
public bool MoveNext()
{
   do
   {
      mCurrent = mReader.ReadLine();
   }while (mIgnoreBlankLines && mCurrent != null && mCurrent.Length == 0);
   return mCurrent != null;
}
public void Dispose()
{
   mReader.Close();
}
  }
}
测试代码：
using System;
using System.IO;
using System.Text;
using NUnit.Framework;
using Forks.Test;
namespace Forks.Utils.IO
{
  [TestFixture]
public class LineReaderTest
{
const string TestLines = @"abc asd ewr afa e
  start with blanks
end with blanks
oo×?abc123!@#
end of text!";
[Test]
public void ReadFromReader()
{
   doTest(new LineReader(new StringReader(TestLines)));
}
[Test]
public void ReadFromFile()
{
   string file = Path.GetTempFileName();
   try
   {
      StringUtil.SaveToFile(TestLines, file, Encoding.GetEncoding("gb2312"));
      doTest(new LineReader(file, Encoding.GetEncoding("gb2312")));
   }
   finally
   {
      FileUtil.SafeDelete(file);
   }
}
[Test]
public void ReadFromStream()
{
   string file = Path.GetTempFileName();
   try
   {
      StringUtil.SaveToFile(TestLines, file, Encoding.GetEncoding("gb2312"));
      using (Stream stream = new FileStream(file, FileMode.Open))
      doTest(new LineReader(stream, Encoding.GetEncoding("gb2312")));
   }
   finally
   {
      FileUtil.SafeDelete(file);
   }
}
void doTest(LineReader reader)
{
   StringBuilder sb = new StringBuilder();
   foreach (string line in reader)
      sb.Append(line + Environment.NewLine);
   Assert.AreEqual(TestLines + Environment.NewLine, sb.ToString());
}
[Test]
public void IgnoreBlankLine()
{
   foreach (string line in new LineReader(new StringReader(TestLines), true))
      Assert.IsTrue(line.Length != 0);
}
}
}

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