C# byte及char FileStream 与StreamReader的区别(转)
1. FileStream是一个较为底层的类,只能简单地读文件到缓存区,而StreamReader封装了一些高级方法如ReadLine()
2. FileStream可读可写,而StreamReader只能读不能写
3. FileStream不能指定编码(因为它看到的只是文件的二进制形式,当然无所谓编码),而StreamReader可以指定编码,一旦指定就不允许再更改,因此编码指定是放在它的构造方法里的。默认编码为System.Text.UTF8Encoding,实际上,在StreamReader的构造方法里,它会对文件进行编码检查,当然也可以不让它检查。
4. 若对是对二进制文件进行操作,最好使用BinaryReader,若要进行写操作,则用StreamWriter,同样StreamWriter也能按指定的编码进行读写
5. StreamReader的构造方法不一定需要FileStream,只需要文件名即可
6. StreamReader关闭后,与之相关的FileStream没有关闭,(通过FileStream的CanRead的测试)
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。这是这两种类的一个重要区别,如果你是准备读取byte数据的话,用StreamReader读取然后用 System.Text.Encoding.Default.GetBytes转化的话,如下,则可能出现数据丢失的情况,如byte数据的个数不对等。因此操作byte数据时要用FileStream。
string textContent = fileStream.ReadToEnd();byte[] bytes = System.Text.Encoding.Default.GetBytes(textContent);
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:
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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 |
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:
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