如何锁定文件，读取其内容并覆盖它？

Question

我需要读取文件的内容并在文件锁定时覆盖它。我不希望文件在读取和写入操作之间解锁。

using (var file = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None)) 
{ 
    using (var reader = new StreamReader(file, Encoding.Unicode)) 
    using (var writer = new StreamWriter(file, Encoding.Unicode)) 
    { 
    // read 
    // calculate new content 
    // overwrite - how do I do this??? 
    } 
} 

如果我用两个FileStream S，实例作家当文件被清除，但该文件将读者和作家之间的实例进行简要解锁。

using (var reader = new StreamReader(new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Read, FileShare.None))) 
{ 
    // read 
    // calculate new content 
} 

using (var writer = new StreamWriter(new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None))) 
{ 
    // write 
} 

Answer 1

如果你把开原的FileStream你可以做到这一点：

using (var file = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None)) 
{ 
    // This overload will leave the underlying stream open 
    using (var reader = new StreamReader(file, Encoding.Unicode, true, 4096, true)) 
    { 
     //Read 
    } 

    file.SetLength(0); //Truncate the file and seek to 0 

    using (var writer = new StreamWriter(file, Encoding.Unicode)) 
    { 
     //Write the new data 
    } 
}