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c# - 为什么这个拆分/合并程序在 .txt 中表现良好但在 .jpg 中表现不佳

问题描述

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace Homework
{
    class Program
    {
        static void Main(string[] args)
        {
            string mode = args[0];
            string name = args[1];

            if(mode == "split")
            {
                FileInfo fileinfo = new FileInfo(name);
                int fileSize = (int)fileinfo.Length;
                int partSize = 1024;
                int numberOfPart = (int)Math.Ceiling((double)fileSize / partSize);

                string chunkName = "";
                int byteRemaining = fileSize;

                FileStream list = File.OpenWrite(name + "_list");
                StreamWriter list_write = new StreamWriter(list, System.Text.Encoding.UTF8);

                list_write.WriteLine(name);         //list 파일 첫 줄에 원본 파일 이름 저장
                Console.WriteLine(name + "_list");


                for(int count = 1; count <= numberOfPart; count++)
                {
                    byte[] buffer = new byte[partSize];
                    chunkName = string.Format("{0}_{1}", name, count);
                    int chunkSize;

                    FileStream origin = File.OpenRead(name);
                    BinaryReader origin_read = new BinaryReader(origin);

                    if(byteRemaining >= partSize)
                    {
                        chunkSize = partSize;
                    }
                    else
                    {
                        chunkSize = byteRemaining;
                    }

                    buffer = origin_read.ReadBytes(chunkSize);      //원본 읽기

                    FileStream chunk = File.OpenWrite(chunkName);
                    BinaryWriter chunk_write = new BinaryWriter(chunk);

                    chunk_write.Write(buffer);                      //chunk에 쓰기

                    byteRemaining -= chunkSize;

                    list_write.WriteLine(chunkName);                //chunkName도 list 파일에 저장
                    Console.WriteLine(chunkName);

                    origin_read.Close();
                    chunk_write.Close();

                }
                list_write.Close();




            }
            else if(mode == "merge")
            {
                FileStream list = File.OpenRead(name);          //list 파일 읽는 스트림
                StreamReader list_read = new StreamReader(list, Encoding.Default, true);
                string originName = list_read.ReadLine();

                FileStream origin = File.OpenWrite(originName); //origin 파일 다시 만드는 스트림     
                BinaryWriter origin_write = new BinaryWriter(origin);

                int partSize = 1024;


                while(list_read.EndOfStream == false)           //list 파일이 끝날때까지 읽어들임
                {
                    string chunkName = list_read.ReadLine();
                    byte[] buffer = new byte[partSize];

                    FileStream chunk = File.OpenRead(chunkName);        //각 chunk 읽는 스트림
                    BinaryReader chunk_read = new BinaryReader(chunk);
                    FileInfo fileinfo = new FileInfo(chunkName);

                    buffer = chunk_read.ReadBytes((int)fileinfo.Length);    //파일 크기만큼 buffer로 읽어옴

                    origin_write.Write(buffer);                             //buffer로 옮긴 내용 원본파일에 쓰기

                      
                }
                 
                



            }

            Console.ReadKey();
        }
    }
}

*预期的

*问题

标签： c#

解决方案

问题：

您的代码的问题是，当您将文件拆分为部分/部分时，而不是将文件拆分为单独的文件，每个文件都包含下一个字节的部分，您每次都从头开始拆分文件，导致错误合并文件（演示问题的图像）

解决方案：

因此，您只需移出for loop3 行特定的代码，使您的代码如下所示：

FileStream origin = File.OpenRead(name); // 1st line
BinaryReader origin_read = new BinaryReader(origin); // 2nd line

for (int count = 1; count <= numberOfPart; count++)
{
 ...
}
origin_read.Close(); //3rd line
list_write.Close();

推荐解决方案：

虽然，这里也是推荐的解决方案。

using System;
using System.IO;
using System.Linq;

namespace Homework
{
    class Program
    {
        static void Main(string[] args)
        {
            string mode = args[0];
            string file = args[1]; // sourcefile or sourcefile_list

            try{
                switch (mode){
                    case "split":

                        byte[] buffer = File.ReadAllBytes(file);
                        int partSize = 1024;
                        int numberOfPart = (int)Math.Ceiling((double)buffer.Length / partSize);
                        string chunkPathName; // The path-and-name of the chunk-file

                        // go through all parts
                        for (int count = 0; count < numberOfPart; count++)
                        {
                            chunkPathName = file + "_" + (count + 1);

                            //write all bytes to the destination-chunk file from a specific point and on.... and then "pass"/write the chuck's path-name into the _list file
                            File.WriteAllBytes(chunkPathName, buffer.Skip(count * partSize).Take(partSize).ToArray());
                            File.AppendAllText(file + "_list", chunkPathName + "\n");
                            Console.WriteLine("Splitting: " + chunkPathName);
                        }

                        break; // exit switch
                    case "merge":

                        // create a stream pointing to your desired-destination/origin-file
                        var originstream = new FileStream(file.Remove(file.Length - "_list".Length, "_list".Length), FileMode.Create);
                        Console.WriteLine("destination path = " + file.Remove(file.Length - "_list".Length) + "\n");

                        // go through each line of the file (_list)
                        foreach (string _chunkPathName in File.ReadAllLines(file))
                        {
                            Console.WriteLine("Merging: " + _chunkPathName);

                            // read all bytes from chunk and append them into the origin-file
                            byte[] chunk = File.ReadAllBytes(_chunkPathName);
                            originstream.Write(chunk, 0, chunk.Length);
                        }

                        // close the stream
                        originstream.Close();

                        break; // exit switch
                }

                Console.WriteLine("\n" + mode + " is done!");
            }catch (Exception ex){
                //code for any other type of exception
            }

            Console.ReadKey(); 
        }
    }
}

我也试图用评论说得足够清楚..

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