.net MemoryStream、StreamWriter、FileStream 组合在组合时导致特殊字符

Question

您好，我有以下代码，我从我正在处理的一项更大的任务中缩减了这些代码。本质上，尽管我发现将内存流组合在一起时，我在连接位置上得到了一个特殊字符。以下是显示问题的运行应用程序的完整代码。在 Visual Studio 代码中打开生成的 export.csv 文件，代码在第 3 行的开头显示一个特殊字符。如果您在 excel 中打开 CSV，您会注意到第 3 行的开头与其他行的外观不同。

using System;
using System.IO;
using System.Text;

namespace testingMemory
{
    class Program
    {
        static void Main(string[] args)
        {
            var stream1 = GetMemoryStream("section1");
            var stream2 = GetMemoryStream("section2");

            var fileStream = new FileStream("export.csv", FileMode.Truncate, FileAccess.Write);

            stream1.WriteTo(fileStream);
            stream2.WriteTo(fileStream);
        }

        public static MemoryStream GetMemoryStream(string section)
        {
            var wrapper = "\"";

            var memoryStream = new MemoryStream();

            var streamWriter = new StreamWriter(memoryStream, Encoding.UTF8);

            streamWriter.WriteLine($"{wrapper}{section}{wrapper},{wrapper}1{wrapper}");
            streamWriter.Flush();

            streamWriter.WriteLine($"{wrapper}{section}{wrapper},{wrapper}2{wrapper}");
            streamWriter.Flush();

            return memoryStream;
        }
    }
}

Answer 1

每个流都包含一个 byte order mark。当您同时复制两者时，第一个流中的字节顺序标记用作文件的 BOM，而第二个只是中间的垃圾。您的内存流不应包含 BOM：

using System;
using System.IO;
using System.Text;

namespace testingMemory
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var stream1 = GetMemoryStream("section1"))
            using (var stream2 = GetMemoryStream("section2"))
            {
                using (var fileStream = new FileStream("d:\export.csv", FileMode.Truncate, FileAccess.Write))
                {
                    stream1.WriteTo(fileStream);
                    stream2.WriteTo(fileStream);
                }
            }
        }

        public static MemoryStream GetMemoryStream(string section)
        {
            var wrapper = "\"";

            var memoryStream = new MemoryStream();

            // Using a non-default UTF-8 encoding with BOM not used: 
            var streamWriter = new StreamWriter(memoryStream, new UTF8Encoding(false));

            streamWriter.WriteLine($"{wrapper}{section}{wrapper},{wrapper}1{wrapper}");
            streamWriter.Flush();

            streamWriter.WriteLine($"{wrapper}{section}{wrapper},{wrapper}2{wrapper}");
            streamWriter.Flush();

            return memoryStream;
        }
    }
}

.net MemoryStream、StreamWriter、FileStream 组合在组合时导致特殊字符

.net MemoryStream, StreamWriter, FileStream combo causes special character when combining

.net

csv

memorystream