怎样用 C# 快速比较 2 个文件是否是相同的文件？
2024-09-01 11:36:40
方案1：
直接贴代码了：
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks; namespace FileCompareDemo
{
public class FileHelper
{
const int BYTES_TO_READ = sizeof(Int64); public static bool FilesAreEqual(FileInfo first, FileInfo second)
{
if (first.Length != second.Length)
return false; if (string.Equals(first.FullName, second.FullName, StringComparison.OrdinalIgnoreCase))
return true; int iterations = (int)Math.Ceiling((double)first.Length / BYTES_TO_READ); using (FileStream fs1 = first.OpenRead())
using (FileStream fs2 = second.OpenRead())
{
byte[] one = new byte[BYTES_TO_READ];
byte[] two = new byte[BYTES_TO_READ]; for (int i = ; i < iterations; i++)
{
fs1.Read(one, , BYTES_TO_READ);
fs2.Read(two, , BYTES_TO_READ); if (BitConverter.ToInt64(one, ) != BitConverter.ToInt64(two, ))
return false;
}
} return true;
} public static bool FilesAreEqual_OneByte(FileInfo first, FileInfo second)
{
if (first.Length != second.Length)
return false; if (string.Equals(first.FullName, second.FullName, StringComparison.OrdinalIgnoreCase))
return true; using (FileStream fs1 = first.OpenRead())
using (FileStream fs2 = second.OpenRead())
{
for (int i = ; i < first.Length; i++)
{
if (fs1.ReadByte() != fs2.ReadByte())
return false;
}
} return true;
} public static bool FilesAreEqual_Hash(FileInfo first, FileInfo second)
{
byte[] firstHash = MD5.Create().ComputeHash(first.OpenRead());
byte[] secondHash = MD5.Create().ComputeHash(second.OpenRead()); for (int i = ; i < firstHash.Length; i++)
{
if (firstHash[i] != secondHash[i])
return false;
}
return true;
}
}
}
方案2：
直接贴代码了：
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace FileCompareDemo
{
public static class FileHelper2
{
public static bool FilesContentsAreEqual(FileInfo fileInfo1, FileInfo fileInfo2)
{
if (fileInfo1 == null)
{
throw new ArgumentNullException(nameof(fileInfo1));
} if (fileInfo2 == null)
{
throw new ArgumentNullException(nameof(fileInfo2));
} if (string.Equals(fileInfo1.FullName, fileInfo2.FullName, StringComparison.OrdinalIgnoreCase))
{
return true;
} if (fileInfo1.Length != fileInfo2.Length)
{
return false;
}
else
{
using (var file1 = fileInfo1.OpenRead())
{
using (var file2 = fileInfo2.OpenRead())
{
return StreamsContentsAreEqual(file1, file2);
}
}
}
} private static int ReadFullBuffer(Stream stream, byte[] buffer)
{
int bytesRead = ;
while (bytesRead < buffer.Length)
{
int read = stream.Read(buffer, bytesRead, buffer.Length - bytesRead);
if (read == )
{
// Reached end of stream.
return bytesRead;
} bytesRead += read;
} return bytesRead;
} private static bool StreamsContentsAreEqual(Stream stream1, Stream stream2)
{
const int bufferSize = * sizeof(Int64);
var buffer1 = new byte[bufferSize];
var buffer2 = new byte[bufferSize]; while (true)
{
int count1 = ReadFullBuffer(stream1, buffer1);
int count2 = ReadFullBuffer(stream2, buffer2); if (count1 != count2)
{
return false;
} if (count1 == )
{
return true;
} int iterations = (int)Math.Ceiling((double)count1 / sizeof(Int64));
for (int i = ; i < iterations; i++)
{
if (BitConverter.ToInt64(buffer1, i * sizeof(Int64)) != BitConverter.ToInt64(buffer2, i * sizeof(Int64)))
{
return false;
}
}
}
}
}
}
方案3（异步版本）：
直接贴代码了：
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks; namespace FileCompareDemo
{
public static class FileCompareAsyncHelper
{
static void test(string filePath1, string filePath2)
{
var fi1 = new FileInfo(filePath1);
var fi2 = new FileInfo(filePath2);
Console.WriteLine(FilesContentsAreEqualAsync(fi1, fi2).GetAwaiter().GetResult());
} public static async Task<bool> FilesContentsAreEqualAsync(FileInfo fileInfo1, FileInfo fileInfo2)
{
if (fileInfo1 == null)
{
throw new ArgumentNullException(nameof(fileInfo1));
} if (fileInfo2 == null)
{
throw new ArgumentNullException(nameof(fileInfo2));
} if (string.Equals(fileInfo1.FullName, fileInfo2.FullName, StringComparison.OrdinalIgnoreCase))
{
return true;
} if (fileInfo1.Length != fileInfo2.Length)
{
return false;
}
else
{
using (var file1 = fileInfo1.OpenRead())
{
using (var file2 = fileInfo2.OpenRead())
{
return await StreamsContentsAreEqualAsync(file1, file2).ConfigureAwait(false);
}
}
}
} private static async Task<int> ReadFullBufferAsync(Stream stream, byte[] buffer)
{
int bytesRead = ;
while (bytesRead < buffer.Length)
{
int read = await stream.ReadAsync(buffer, bytesRead, buffer.Length - bytesRead).ConfigureAwait(false);
if (read == )
{
// Reached end of stream.
return bytesRead;
} bytesRead += read;
} return bytesRead;
} private static async Task<bool> StreamsContentsAreEqualAsync(Stream stream1, Stream stream2)
{
const int bufferSize = * sizeof(Int64);
var buffer1 = new byte[bufferSize];
var buffer2 = new byte[bufferSize]; while (true)
{
int count1 = await ReadFullBufferAsync(stream1, buffer1).ConfigureAwait(false);
int count2 = await ReadFullBufferAsync(stream2, buffer2).ConfigureAwait(false); if (count1 != count2)
{
return false;
} if (count1 == )
{
return true;
} int iterations = (int)Math.Ceiling((double)count1 / sizeof(Int64));
for (int i = ; i < iterations; i++)
{
if (BitConverter.ToInt64(buffer1, i * sizeof(Int64)) != BitConverter.ToInt64(buffer2, i * sizeof(Int64)))
{
return false;
}
}
}
}
}
}
谢谢浏览！
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