在c#中无法正常工作的文本文件拆分
在c#中无法正常工作的文本文件拆分
提问于 2017-04-25 19:29:30
我有写到文本文件的要求。如果文件大小超过700MB，则创建新文件并写入。我目前正在用“|”从数据库写数据到文件&然后检查文件大小&拆分成多个文件，但文件splits在行的中间。它应该写入到行尾或新文件中特定行开始。
我需要在新拆分的文件的第一行中写入列名。
我是c#的新手，你能用示例代码给我推荐解决方案吗？
请找到下面的代码来拆分文件
private static void ReadWriteToFile(string fileNames)
{
string sourceFileName = fileNames;
string destFileLocation = Path.GetDirectoryName(fileNames);
int index = 0;
long maxFileSize = 700 * 1024 * 1024;
byte[] buffer = new byte[65536];
using (Stream source = File.OpenRead(sourceFileName))
{
while (source.Position < source.Length)
{
index++;
string newFileName = Path.Combine(destFileLocation, Path.GetFileNameWithoutExtension(sourceFileName));
newFileName += index.ToString() + Path.GetExtension(sourceFileName);
using (Stream destination = File.OpenWrite(newFileName))
{
while (destination.Position < maxFileSize)
{
int bytes = source.Read(buffer, 0, (int)Math.Min(maxFileSize, buffer.Length));
destination.Write(buffer, 0, bytes);
if (bytes < Math.Min(maxFileSize, buffer.Length))
{
break;
}
}
}
}
}
}提前谢谢。
你能告诉我有没有其他最好的办法吗？
回答 1
Stack Overflow用户
发布于 2017-04-25 21:49:22
试试这个，重写我在刚开始的c#时代写的行文件拆分器。(您只需将列标题作为字符串添加到新文件的开头。)
private static void SplitAfterMBytes(int splitAfterMBytes, string filename)
{
// Variable for max. file size.
var maxFileSize = splitAfterMBytes * 1048576;
int fileCount = 0;
long byteCount = 0;
StreamWriter writer = null;
try
{
var inputFile = new FileInfo(filename);
var index = filename.LastIndexOf('.');
//get only the name of the file.
var fileStart = filename.Substring(0, index);
// get the file extension
var fileExtension = inputFile.Extension;
// generate a new file name.
var outputFile = fileStart + '_' + fileCount++ + fileExtension;
// file format is like: QS_201101_321.txt.
writer = new StreamWriter(outputFile);
using (var reader = new StreamReader(filename))
{
for (string str; (str = reader.ReadLine()) != null;)
{
byteCount = byteCount + System.Text.Encoding.Unicode.GetByteCount(str);
if (byteCount >= maxFileSize)
{
// max number of bytes reached
// write into the old file, without Newline,
// so that no extra line is written.
writer.Write(str);
// 1. close the actual file.
writer.Close();
// 2. open a new file with number incresed by 1.
outputFile = fileStart + '_' + fileCount++ + fileExtension;
writer = new StreamWriter(outputFile);
byteCount = 0; //reset the counter.
}
else
{
// Write into the old file.
// Use a Linefeed, because Write works without LF.
// like Java ;)
writer.Write(str);
writer.Write(writer.NewLine);
}
}
}
}
catch (Exception ex)
{
// do something useful, like: Console.WriteLine(ex.Message);
}
finally
{
writer.Dispose();
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/43609457
复制相关文章
相似问题
腾讯云开发者
