Email Format Converter untuk .NET

Aspose.Email LowCode Converter menyediakan API yang disederhanakan, peringkat tinggi untuk menukar mesej e-mel antara format yang berbeza dengan kerumitan kod minimum. panduan pemaju ini meliputi fungsi teras, corak pelaksanaan, dan amalan terbaik untuk menggunakan penukar dalam aplikasi .NET.

Perbincangan:EmailLowCode

The Aspose.Email.LowCode namespace mengandungi kelas yang direka untuk menyempurnakan operasi penukaran format e-mel. komponen utama ialah Converter kelas, yang menawarkan kaedah statik untuk menukar mesej e-mel antara format popular termasuk EML, MSG, HTML, MHT, dan MHTML.

Komponen Utama

  • Converter : kaedah penukaran statik untuk transformasi format e-mel
  • IoutputHandler : Antara muka untuk mengendalikan aliran output yang ditukar
  • FolderOutputHandler : Pelaksanaan terbina dalam untuk penyimpanan output berasaskan folder

Memulakan

Installation

Pemasangan paket Aspose.Email melalui NuGet Package Manager:

Install-Package Aspose.Email

Pernyataan Namespace 

using Aspose.Email.LowCode;
using System.IO;
using System.Threading.Tasks;

Kaedah Konversi Utama

Format Penukaran Generik

The Convert kaedah menyediakan penukaran format yang fleksibel dengan spesifikasi jenis output yang jelas:

public static Task Convert(Stream input, string nameWithExtension, IOutputHandler handler, string outputType)

Pelaksanaan contoh:

using var inputStream = File.OpenRead("email.eml");
var outputHandler = new FolderOutputHandler(@"C:\ConvertedEmails");

await Converter.Convert(inputStream, "email.eml", outputHandler, "html");

Kaedah Konversi Khas

Penukar menyediakan kaedah khusus untuk senario penukaran biasa:

Menukar kepada format HTML 

await Converter.ConvertToHtml(inputStream, "email.eml", outputHandler);

Menukar kepada format MSG 

await Converter.ConvertToMsg(inputStream, "email.eml", outputHandler);

Menukar kepada format EML 

await Converter.ConvertToEml(inputStream, "email.msg", outputHandler);

Menukar kepada format MHTML/MHT 

await Converter.ConvertToMhtml(inputStream, "email.eml", outputHandler);
await Converter.ConvertToMht(inputStream, "email.eml", outputHandler);

EML/MSG Konversi spesifik

Untuk pengesanan format automatik antara Perbezaan EML dan MSG Format yang:

await Converter.ConvertEmlOrMsg(inputStream, "email.eml", outputHandler, "html");

Pelaksanaan pengendali output

Penggunaan FolderoutputHandler

yang dibina dalam FolderOutputHandler Kelas secara automatik menyimpan fail yang ditukar ke direktori tertentu:

public class FolderOutputHandler : IOutputHandler
{
    public FolderOutputHandler(string path)
    public string Path { get; set; }
}

Penggunaan contoh:

var outputHandler = new FolderOutputHandler(@"C:\OutputDirectory");

Pengedar output disesuaikan

Pelaksanaan yang IOutputHandler antara muka untuk pemprosesan output tersuai:

public class CustomOutputHandler : IOutputHandler
{
    public async Task AddOutputStream(string name, Func<Stream, Task> writeAction)
    {
        // Custom async implementation
        using var customStream = CreateCustomStream(name);
        await writeAction(customStream);
    }
    
    public void AddOutputStream(string name, Action<Stream> writeAction)
    {
        // Custom synchronous implementation
        using var customStream = CreateCustomStream(name);
        writeAction(customStream);
    }
}

Format Matriks yang disokong

Pengenalan FormatFormat outputMethod
Perbezaan EMLPerbezaan antara HTML, MSG, MHTML dan MHTConvertToHtml(), ConvertToMsg(), dan sebagainya.
MSGPerbezaan antara HTML, EML, MHTML dan MHTConvertToHtml(), ConvertToEml(), dan sebagainya.
Semua format e-melPengguna spesifikConvert() dengan parameter jenis output

Model Pelaksanaan Lanjutan

Pelaksanaan Batch Processing 

public class EmailBatchConverter
{
    private readonly IOutputHandler _outputHandler;
    
    public EmailBatchConverter(IOutputHandler outputHandler)
    {
        _outputHandler = outputHandler;
    }
    
    public async Task ConvertBatch(IEnumerable<string> emailFiles, string outputFormat)
    {
        var conversionTasks = emailFiles.Select(async file =>
        {
            using var stream = File.OpenRead(file);
            var fileName = Path.GetFileName(file);
            
            await Converter.Convert(stream, fileName, _outputHandler, outputFormat);
        });
        
        await Task.WhenAll(conversionTasks);
    }
}

Kesilapan pengendalian pattern 

public async Task<ConversionResult> SafeConvert(string inputFile, string outputFormat)
{
    try
    {
        using var inputStream = File.OpenRead(inputFile);
        var outputHandler = new FolderOutputHandler(@"C:\Output");
        var fileName = Path.GetFileName(inputFile);
        
        await Converter.Convert(inputStream, fileName, outputHandler, outputFormat);
        
        return new ConversionResult { Success = true };
    }
    catch (Exception ex)
    {
        return new ConversionResult 
        { 
            Success = false, 
            ErrorMessage = ex.Message 
        };
    }
}

Memori-optimum pemprosesan aliran 

public async Task ConvertWithMemoryOptimization(string inputFile)
{
    using var inputStream = new FileStream(inputFile, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, useAsync: true);
    var outputHandler = new FolderOutputHandler(@"C:\Output");
    
    await Converter.ConvertToHtml(inputStream, Path.GetFileName(inputFile), outputHandler);
}

Konfigurasi dan Customization

Struktur direktori output

Apabila menggunakan FolderOutputHandler, penukar mengekalkan struktur fail asal:

var outputHandler = new FolderOutputHandler(@"C:\ConvertedEmails");
// Original: sample.eml → Output: C:\ConvertedEmails\sample.html

Strategi nama tersuai

Mengimplementasikan nama fail tersuai melalui pengedar output khusus:

public class TimestampOutputHandler : IOutputHandler
{
    private readonly string _basePath;
    
    public TimestampOutputHandler(string basePath)
    {
        _basePath = basePath;
    }
    
    public async Task AddOutputStream(string name, Func<Stream, Task> writeAction)
    {
        var timestamp = DateTime.Now.ToString("yyyyMMdd_HHmmss");
        var newName = $"{timestamp}_{name}";
        var filePath = Path.Combine(_basePath, newName);
        
        using var fileStream = File.Create(filePath);
        await writeAction(fileStream);
    }
    
    // Synchronous implementation omitted for brevity
}

Pertimbangan prestasi

Operasi Asynchronous

Semua kaedah penukaran kembali Task objek, yang membolehkan pemprosesan asynchronous yang cekap:

public async Task ProcessMultipleEmailsAsync()
{
    var tasks = new[]
    {
        ConvertEmailAsync("email1.eml"),
        ConvertEmailAsync("email2.msg"),
        ConvertEmailAsync("email3.eml")
    };
    
    await Task.WhenAll(tasks);
}

Pengurusan Sumber

Penyelesaian aliran yang betul adalah penting untuk prestasi yang optimum:

// Correct pattern
using (var inputStream = File.OpenRead("email.eml"))
{
    await Converter.ConvertToHtml(inputStream, "email.eml", outputHandler);
}

// Alternative using statement
using var inputStream = File.OpenRead("email.eml");
await Converter.ConvertToHtml(inputStream, "email.eml", outputHandler);

Mengoptimumkan penggunaan memori

Untuk fail e-mel yang besar, pertimbangkan pendekatan streaming:

public async Task ConvertLargeEmail(string inputPath)
{
    const int bufferSize = 65536; // 64KB buffer
    
    using var inputStream = new FileStream(inputPath, FileMode.Open, FileAccess.Read, FileShare.Read, bufferSize, true);
    var outputHandler = new FolderOutputHandler(@"C:\Output");
    
    await Converter.ConvertToHtml(inputStream, Path.GetFileName(inputPath), outputHandler);
}

Contoh Integrasi

ASP.NET Integrasi API Web Core 

[ApiController]
[Route("api/[controller]")]
public class EmailConverterController : ControllerBase
{
    [HttpPost("convert")]
    public async Task<IActionResult> ConvertEmail(IFormFile emailFile, [FromQuery] string format = "html")
    {
        if (emailFile == null || emailFile.Length == 0)
            return BadRequest("No file provided");
        
        try
        {
            using var inputStream = emailFile.OpenReadStream();
            var outputHandler = new MemoryOutputHandler();
            
            await Converter.Convert(inputStream, emailFile.FileName, outputHandler, format);
            
            return File(outputHandler.GetContent(), GetContentType(format), $"converted.{format}");
        }
        catch (Exception ex)
        {
            return StatusCode(500, $"Conversion failed: {ex.Message}");
        }
    }
    
    private string GetContentType(string format) => format.ToLower() switch
    {
        "html" => "text/html",
        "mhtml" => "message/rfc822",
        "eml" => "message/rfc822",
        _ => "application/octet-stream"
    };
}

Pengenalan Perkhidmatan Windows 

public class EmailConverterService : BackgroundService
{
    private readonly string _watchFolder;
    private readonly string _outputFolder;
    
    public EmailConverterService(IConfiguration config)
    {
        _watchFolder = config["EmailConverter:WatchFolder"];
        _outputFolder = config["EmailConverter:OutputFolder"];
    }
    
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        var watcher = new FileSystemWatcher(_watchFolder, "*.eml");
        watcher.Created += async (sender, e) => await ProcessEmailFile(e.FullPath);
        watcher.EnableRaisingEvents = true;
        
        while (!stoppingToken.IsCancellationRequested)
        {
            await Task.Delay(1000, stoppingToken);
        }
    }
    
    private async Task ProcessEmailFile(string filePath)
    {
        using var inputStream = File.OpenRead(filePath);
        var outputHandler = new FolderOutputHandler(_outputFolder);
        
        await Converter.ConvertToHtml(inputStream, Path.GetFileName(filePath), outputHandler);
    }
}

Troubleshooting

Masalah dan Penyelesaian Bersama

IssueSolution
FileNotFoundExceptionSemak laluan fail input dan keizinan
UnauthorizedAccessExceptionSemak direktori output menulis keizinan
OutOfMemoryExceptionMenggunakan pendekatan streaming untuk fail besar
InvalidOperationExceptionMemastikan format e-mel yang sah untuk fail input

Tag: tips debugging

Membolehkan log terperinci untuk penyelesaian masalah:

public async Task ConvertWithLogging(string inputFile)
{
    var logger = LoggerFactory.Create(builder => builder.AddConsole()).CreateLogger<EmailConverter>();
    
    try
    {
        logger.LogInformation($"Starting conversion of {inputFile}");
        
        using var inputStream = File.OpenRead(inputFile);
        var outputHandler = new FolderOutputHandler(@"C:\Output");
        
        await Converter.ConvertToHtml(inputStream, Path.GetFileName(inputFile), outputHandler);
        
        logger.LogInformation($"Successfully converted {inputFile}");
    }
    catch (Exception ex)
    {
        logger.LogError(ex, $"Failed to convert {inputFile}");
        throw;
    }
}
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