电子邮件格式转换器
如何在 .NET 中将 EML 和 MSG 电子邮件文件转换为 HTML

如何在 .NET 中将 EML 和 MSG 电子邮件文件转换为 HTML

将电子邮件文件转换为HTML格式,对于基于Web的应用程序、Email存档系统和现代文档管理解决方案至关重要。HTML提供了一个多元化的形式,允许易于查看、风格化和整合以Web为基础的内容。The Aspose.email LowCode Converter简化了这个过程,使开发人员能够转型 EML 和 MSG 将文件输入到 HTML 以最小代码复杂性.

原則

在实施电子邮件转换到HTML之前,确保您的开发环境包括:

  • Visual Studio 2019 或更高版本 (或任何兼容的 .NET IDE)
  • .NET 6.0 SDK 或更高
  • Aspose.Email NuGet 包
  • C#和文件处理的基本知识

步骤 1: 通过 NuGet 安装 Aspose.Email

安装 Aspose.Email 包,使用其中一个方法:

包装管理器:

Install-Package Aspose.Email

包装管理员:

  • 在 Solution Explorer 中右键单击您的项目
  • 选择“管理 NuGet 包"
  • 搜索“Aspose.Email"
  • 点击“安装"

包装在 .csproj 中参考:

<PackageReference Include="Aspose.Email" Version="24.3.0" />

步骤2:编写转换代码

下面是一个完整的例子,表明单个文件从EML/MSG转换为HTML:

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

namespace EmailToHtmlConverter
{
    class Program
    {
        static async Task Main(string[] args)
        {
            try
            {
                // Define input and output paths
                string inputFilePath = @"C:\Emails\sample.eml";
                string outputDirectory = @"C:\ConvertedEmails";
                
                // Create output directory if it doesn't exist
                Directory.CreateDirectory(outputDirectory);
                
                // Create input stream from the email file
                using var inputStream = File.OpenRead(inputFilePath);
                
                // Set up the output handler to save converted files
                var outputHandler = new FolderOutputHandler(outputDirectory);
                
                // Get the filename for processing
                string fileName = Path.GetFileName(inputFilePath);
                
                // Convert the email file to HTML
                await Converter.ConvertToHtml(inputStream, fileName, outputHandler);
                
                Console.WriteLine($"Successfully converted {fileName} to HTML format");
                Console.WriteLine($"Output saved to: {outputDirectory}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Conversion failed: {ex.Message}");
            }
        }
    }
}

代码破解:

  • 输入流创建: File.OpenRead() 创建源电子邮件文件的流
  • 输出处理器设置: FolderOutputHandler 管理已转换的 HTML 文件存储的地方
  • 转换执行: Converter.ConvertToHtml() 实现真正的转型
  • 资源管理: using 声明确保文件流的适当处理

步骤3:处理多个文件(Batch Conversion)

要同时处理多个电子邮件文件,执行包转换:

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

public class BatchEmailConverter
{
    public static async Task ConvertMultipleEmailsToHtml()
    {
        try
        {
            // Define directories
            string inputDirectory = @"C:\EmailFiles";
            string outputDirectory = @"C:\ConvertedEmails";
            
            // Create output directory
            Directory.CreateDirectory(outputDirectory);
            
            // Get all EML and MSG files from input directory
            var emailFiles = Directory.GetFiles(inputDirectory, "*.*")
                .Where(file => file.EndsWith(".eml", StringComparison.OrdinalIgnoreCase) || 
                              file.EndsWith(".msg", StringComparison.OrdinalIgnoreCase))
                .ToArray();
            
            Console.WriteLine($"Found {emailFiles.Length} email files to convert");
            
            // Set up output handler
            var outputHandler = new FolderOutputHandler(outputDirectory);
            
            // Process each file
            var conversionTasks = emailFiles.Select(async filePath =>
            {
                try
                {
                    using var inputStream = File.OpenRead(filePath);
                    string fileName = Path.GetFileName(filePath);
                    
                    await Converter.ConvertToHtml(inputStream, fileName, outputHandler);
                    
                    Console.WriteLine($"✓ Converted: {fileName}");
                }
                catch (Exception ex)
                {
                    Console.WriteLine($"✗ Failed to convert {Path.GetFileName(filePath)}: {ex.Message}");
                }
            });
            
            // Execute all conversions concurrently
            await Task.WhenAll(conversionTasks);
            
            Console.WriteLine("Batch conversion completed!");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Batch conversion failed: {ex.Message}");
        }
    }
}

先进主题

定制输出名称

创建一个自定义输出处理器来控制文件名称:

public class TimestampOutputHandler : IOutputHandler
{
    private readonly string _basePath;
    
    public TimestampOutputHandler(string basePath)
    {
        _basePath = basePath;
        Directory.CreateDirectory(_basePath);
    }
    
    public async Task AddOutputStream(string name, Func<Stream, Task> writeAction)
    {
        // Add timestamp prefix to the filename
        var timestamp = DateTime.Now.ToString("yyyyMMdd_HHmmss");
        var nameWithoutExtension = Path.GetFileNameWithoutExtension(name);
        var extension = ".html"; // Force HTML extension
        var newFileName = $"{timestamp}_{nameWithoutExtension}{extension}";
        var outputPath = Path.Combine(_basePath, newFileName);
        
        using var fileStream = File.Create(outputPath);
        await writeAction(fileStream);
        
        Console.WriteLine($"Created: {newFileName}");
    }
    
    public void AddOutputStream(string name, Action<Stream> writeAction)
    {
        // Synchronous version
        var timestamp = DateTime.Now.ToString("yyyyMMdd_HHmmss");
        var nameWithoutExtension = Path.GetFileNameWithoutExtension(name);
        var extension = ".html";
        var newFileName = $"{timestamp}_{nameWithoutExtension}{extension}";
        var outputPath = Path.Combine(_basePath, newFileName);
        
        using var fileStream = File.Create(outputPath);
        writeAction(fileStream);
    }
}

// Usage example:
var customHandler = new TimestampOutputHandler(@"C:\ConvertedEmails");
await Converter.ConvertToHtml(inputStream, fileName, customHandler);

全面错误处理

为生产环境实施强大的错误处理:

public class RobustEmailConverter
{
    public static async Task<ConversionResult> ConvertEmailToHtml(string inputPath, string outputDirectory)
    {
        var result = new ConversionResult();
        
        try
        {
            // Validate input file exists
            if (!File.Exists(inputPath))
            {
                throw new FileNotFoundException($"Input file not found: {inputPath}");
            }
            
            // Validate file extension
            var extension = Path.GetExtension(inputPath).ToLower();
            if (extension != ".eml" && extension != ".msg")
            {
                throw new ArgumentException($"Unsupported file format: {extension}");
            }
            
            // Create output directory
            Directory.CreateDirectory(outputDirectory);
            
            // Perform conversion
            using var inputStream = File.OpenRead(inputPath);
            var outputHandler = new FolderOutputHandler(outputDirectory);
            string fileName = Path.GetFileName(inputPath);
            
            await Converter.ConvertToHtml(inputStream, fileName, outputHandler);
            
            result.Success = true;
            result.OutputPath = Path.Combine(outputDirectory, Path.ChangeExtension(fileName, ".html"));
            result.Message = "Conversion completed successfully";
        }
        catch (FileNotFoundException ex)
        {
            result.Success = false;
            result.ErrorType = "FileNotFound";
            result.Message = ex.Message;
        }
        catch (UnauthorizedAccessException ex)
        {
            result.Success = false;
            result.ErrorType = "AccessDenied";
            result.Message = $"Access denied: {ex.Message}";
        }
        catch (ArgumentException ex)
        {
            result.Success = false;
            result.ErrorType = "InvalidArgument";
            result.Message = ex.Message;
        }
        catch (Exception ex)
        {
            result.Success = false;
            result.ErrorType = "UnknownError";
            result.Message = $"Unexpected error: {ex.Message}";
        }
        
        return result;
    }
}

public class ConversionResult
{
    public bool Success { get; set; }
    public string Message { get; set; }
    public string ErrorType { get; set; }
    public string OutputPath { get; set; }
}

结论

Aspose.Email LowCode Converter 提供一个精致的解决方案,将 EML 和 MSG 文件转换为 HTML 格式:

  • 简化API :复杂转换所需的最小代码
  • Batch Processing :有效地处理多个文件与当前操作
  • 灵活输出 :专门命名和存储要求的自定义处理器
  • Robust Error Handling :生产使用的全面例外管理
  • 无同步支持 :非封锁操作,以提高应用性能

这种方法使开发人员能够无缝地将电子邮件转换为HTML集成到网页应用程序、文档管理系统和电子文件存档解决方案中.

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