FileStream读写文件【StreamWriter 和 StreamReader】
Posted on 2007-11-16 17:25 停留的风 阅读(32306) 评论(11) 编辑 收藏 举报
FileStream对象表示在磁盘或网络路径上指向文件的流。这个类提供了在文件中读写字节的方法,但经常使用StreamReader或StreamWriter执行这些功能。这是因为FileStream类操作的是字节和字节数组,而Stream类操作的是字符数据。字符数据易于使用,但是有些操作,比如随机文件访问(访问文件中间某点的数据),就必须由FileStream对象执行.
其中创建FileStream对象最简单的构造函数如下:
FileStream类操作的是字节和字节数组,而Stream类操作的是字符数据
StreamWriter允许将字符和字符串写入文件,它处理底层的转换,向FileStream对象写入数据。StreamReader也类似。
实例:
其中创建FileStream对象最简单的构造函数如下:
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FileStream file = new FileStream(fileName,FileMode.Member);
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FileStream file = new FileStream(fileName, FileMode.Member, FileAccess.Member);
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而FileAccess的成员:
成 员 |
说 明 |
Read |
打开文件,用于只读 |
Write |
打开文件,用于只写 |
ReadWrite |
打开文件,用于读写 |
对文件进行不是FileAccess枚举成员指定的操作会导致抛出异常。此属性的作用是,基于用户的身份验证级别改变用户对文件的访问权限。
在FileStream构造函数不使用FileAccess枚举参数的版本中,使用默认值FileAccess. ReadWrite。
FileMode枚举成员,使用每个值会发生什么,取决于指定的文件名是否表示已有的文件。
成 员 |
文 件 存 在 |
文件不存在 |
Append |
打开文件,流指向文件的末尾,只能与枚举FileAccess.Write联合使用 |
创建一个新文件。只能与枚举FileAccess.Write联合使用 |
Create |
删除该文件,然后创建新文件 |
创建新文件 |
CreateNew |
抛出异常 |
创建新文件 |
Open |
打开现有的文件,流指向文件的开头 |
抛出异常 |
OpenOrCreate |
打开文件,流指向文件的开头 |
创建新文件 |
Truncate |
打开现有文件,清除其内容。流指向文件的开头,保留文件的初始创建日期 |
抛出异常 |
StreamWriter允许将字符和字符串写入文件,它处理底层的转换,向FileStream对象写入数据。StreamReader也类似。
实例:
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using System;
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using System.Data;
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using System.IO;
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using System.Text;
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/// <summary>
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/// Summary description for FileReadAndWrite
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/// </summary>
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public class FileReadAndWrite
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{
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public FileReadAndWrite()
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{
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//
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// TODO: Add constructor logic here
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//
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}
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/// <summary>
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/// 用FileStream写文件
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/// </summary>
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/// <param name="str"></param>
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/// <returns></returns>
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public void FileStreamWriteFile(string str)
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{
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byte[] byData;
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char[] charData;
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try
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{
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FileStream nFile = new FileStream("love.txt", FileMode.Create);
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//获得字符数组
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charData = str.ToCharArray();
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//初始化字节数组
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byData = new byte[charData.Length];
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//将字符数组转换为正确的字节格式
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Encoder enc = Encoding.UTF8.GetEncoder();
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enc.GetBytes(charData, 0, charData.Length,byData,0,true);
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nFile.Seek(0, SeekOrigin.Begin);
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nFile.Write(byData, 0, byData.Length);
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}
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catch (Exception ex)
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{
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throw ex;
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}
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}
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/// <summary>
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/// FileStream读取文件
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/// </summary>
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/// <param name="filePath"></param>
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/// <returns></returns>
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public string FileStreamReadFile(string filePath)
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{
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byte[] data = new byte[100];
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char[] charData = new char[100];
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try
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{
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FileStream file = new FileStream(filePath, FileMode.Open);
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//文件指针指向0位置
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file.Seek(0, SeekOrigin.Begin);
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//读入两百个字节
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file.Read(data, 0, 200);
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//提取字节数组
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Decoder dec = Encoding.UTF8.GetDecoder();
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dec.GetChars(data, 0, data.Length, charData, 0);
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}
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catch (Exception ex)
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{
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throw ex;
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}
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return Convert.ToString(charData);
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}
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/// <summary>
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/// StreamWriter写文件
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/// </summary>
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public void StreamWriterWriteFile()
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{
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try
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{
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FileStream nFile = new FileStream("love.txt", FileMode.CreateNew);
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StreamWriter writer = new StreamWriter(nFile);
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writer.WriteLine("I love You!");
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writer.WriteLine("Do you love me!");
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writer.Close();
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}
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catch
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{ }
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}
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/// <summary>
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/// StreamReader读取文件
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/// </summary>
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/// <returns></returns>
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public string StreamReaderReadFile()
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{
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string str="";
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try
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{
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FileStream file = new FileStream("love.txt", FileMode.Open);
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StreamReader sr = new StreamReader(file);
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while (sr.ReadLine()!=null)
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{
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str += sr.ReadLine();
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}
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//或者str = sr.ReadToEnd();
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sr.Close();
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}
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catch
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{ }
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return str;
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}
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}
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