c# - StreamWriter 错误字符

Question

遇到一个问题，streamwriter 在我正在生成的 csv 中生成错误的字符。字符  只出现在文件的开头:

5,"GEN",555555555,,"Evan","Smith",,,,,,,,,,,,,,,,,,,,,,,,,"email@someplace.com"
5,"GEN",555555555,,"Dorathy","Smith",,,,,,,,,,,,,,,,,,,,,,,,,"email@someplace.com"
5,"GEN",555555555,,"Marvin","Smith",,,,,,,,,,,,,,,,,,,,,,,,,"email@someplace.com"
....

在我看来像是编码问题。我尝试过不同的编码和正则表达式来清理字符串，但运气不佳。这是预览代码(虽然并不复杂)。它还作为网络进程运行。

string fileName = includeEmail == false ? "attachment; filename=stuacct_batch.txt" : "attachment; filename=rentals.csv";
Context.Response.Clear();
Context.Response.AddHeader("content-disposition", fileName);
Context.Response.ContentType = includeEmail == false ? "text/plain" : "text/csv";

using (StreamWriter sw = new StreamWriter(Response.OutputStream, Encoding.UTF8))
{   
    string line = "";
    foreach (Student s in students)
    {
        // ... some logic above that that's misc. to this problem 
        line = "5,\"GEN\"," + s.StudentNumber + ",,\"" + s.FirstName + "\",\"" + s.LastName + "\",,,,,,,,,,,,,,,,,,,,,,,,,\"" + s.Email + "\"";
        sw.WriteLine(line);
    }
}

Context.Response.End();
Context.Response.Flush();
Context.ApplicationInstance.CompleteRequest();

Answer 1

您已指定要对流使用 UTF-8 编码，并且这些初始字节是有效的 UTF-8 字节顺序标记 (BOM)。问题显然是您的查看器/编辑器无法正确解码 UTF-8 流。如果仅 BOM 是问题所在，并且您想要创建没有 BOM 的流，则可以创建您自己的 UTF8Encoding 实例。类:

var encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
using (StreamWriter sw = new StreamWriter(Response.OutputStream, encoding)) ...

如果您确实想使用 ASCII 数据，您应该使用该编码:

using (StreamWriter sw = new StreamWriter(Response.OutputStream, Encoding.ASCII)) ...