用 C# 将 HTML 转换为 PDF - 库选项的现实意义

using PuppeteerSharp;
using System.Collections.Concurrent;

public class PdfBrowserPool : IAsyncDisposable
{
    private readonly ConcurrentBag<IBrowser> _available = new();
    private readonly SemaphoreSlim _semaphore;
    private readonly int _maxBrowsers;

    public PdfBrowserPool(int maxBrowsers = 4)
    {
        _maxBrowsers = maxBrowsers;
        _semaphore = new SemaphoreSlim(maxBrowsers, maxBrowsers);
    }

    public async Task InitializeAsync()
    {
        await new BrowserFetcher().DownloadAsync(); // ~280MB download
        for (int i = 0; i < _maxBrowsers; i++)
        {
            var browser = await Puppeteer.LaunchAsync(new LaunchOptions
            {
                Headless = true,
                Args = new[] { "--no-sandbox", "--disable-setuid-sandbox",
                               "--disable-dev-shm-usage" }
            });
            _available.Add(browser);
        }
    }

    public async Task<byte[]> ConvertHtmlToPdf(string html)
    {
        await _semaphore.WaitAsync();
        IBrowser browser = null;
        try
        {
            if (!_available.TryTake(out browser))
                throw new InvalidOperationException("No browser available");

            await using var page = await browser.NewPageAsync();
            await page.SetContentAsync(html, new NavigationOptions
            {
                WaitUntil = new[] { WaitUntilNavigation.Networkidle0 }
            });
            var result = await page.PdfAsync(new PdfOptions
            {
                Format = PaperFormat.A4,
                PrintBackground = true
            });
            return result;
        }
        catch (Exception ex) when (ex is NavigationException or TargetClosedException)
        {
            // Browser crashed — replace it
            browser?.Dispose();
            browser = await Puppeteer.LaunchAsync(new LaunchOptions
            {
                Headless = true,
                Args = new[] { "--no-sandbox", "--disable-setuid-sandbox" }
            });
            throw; // Re-throw after recovery
        }
        finally
        {
            if (browser != null) _available.Add(browser);
            _semaphore.Release();
        }
    }

    public async ValueTask DisposeAsync()
    {
        foreach (var browser in _available)
        {
            await browser.CloseAsync();
            browser.Dispose();
        }
    }
}

Imports PuppeteerSharp
Imports System.Collections.Concurrent
Imports System.Threading

Public Class PdfBrowserPool
    Implements IAsyncDisposable

    Private ReadOnly _available As New ConcurrentBag(Of IBrowser)()
    Private ReadOnly _semaphore As SemaphoreSlim
    Private ReadOnly _maxBrowsers As Integer

    Public Sub New(Optional maxBrowsers As Integer = 4)
        _maxBrowsers = maxBrowsers
        _semaphore = New SemaphoreSlim(maxBrowsers, maxBrowsers)
    End Sub

    Public Async Function InitializeAsync() As Task
        Await (New BrowserFetcher()).DownloadAsync() ' ~280MB download
        For i As Integer = 0 To _maxBrowsers - 1
            Dim browser = Await Puppeteer.LaunchAsync(New LaunchOptions With {
                .Headless = True,
                .Args = New String() {"--no-sandbox", "--disable-setuid-sandbox", "--disable-dev-shm-usage"}
            })
            _available.Add(browser)
        Next
    End Function

    Public Async Function ConvertHtmlToPdf(html As String) As Task(Of Byte())
        Await _semaphore.WaitAsync()
        Dim browser As IBrowser = Nothing
        Try
            If Not _available.TryTake(browser) Then
                Throw New InvalidOperationException("No browser available")
            End If

            Await Using page = Await browser.NewPageAsync()
                Await page.SetContentAsync(html, New NavigationOptions With {
                    .WaitUntil = New WaitUntilNavigation() {WaitUntilNavigation.Networkidle0}
                })
                Dim result = Await page.PdfAsync(New PdfOptions With {
                    .Format = PaperFormat.A4,
                    .PrintBackground = True
                })
                Return result
            End Using
        Catch ex As Exception When TypeOf ex Is NavigationException OrElse TypeOf ex Is TargetClosedException
            ' Browser crashed — replace it
            browser?.Dispose()
            browser = Await Puppeteer.LaunchAsync(New LaunchOptions With {
                .Headless = True,
                .Args = New String() {"--no-sandbox", "--disable-setuid-sandbox"}
            })
            Throw ' Re-throw after recovery
        Finally
            If browser IsNot Nothing Then _available.Add(browser)
            _semaphore.Release()
        End Try
    End Function

    Public Async Function DisposeAsync() As ValueTask Implements IAsyncDisposable.DisposeAsync
        For Each browser In _available
            Await browser.CloseAsync()
            browser.Dispose()
        Next
    End Function
End Class

using IronPdf;

var renderer = new ChromePdfRenderer();
var pdf = renderer.RenderHtmlAsPdf(html);
// Browser pooling, process management, crash recovery — handled internally

Imports IronPdf

Dim renderer As New ChromePdfRenderer()
Dim pdf = renderer.RenderHtmlAsPdf(html)
' Browser pooling, process management, crash recovery — handled internally

using IronPdf;

var renderer = new ChromePdfRenderer();

// Convert from URL — useful when migrating fromwkhtmltopdfURL-based workflows
var pdf = renderer.RenderUrlAsPdf("https://localhost:5001/reports/quarterly");
pdf.SaveAs("report.pdf");

// Convert from local HTML file
var pdfFromFile = renderer.RenderHtmlFileAsPdf("templates/invoice.html");
pdfFromFile.SaveAs("invoice.pdf");

Imports IronPdf

Dim renderer As New ChromePdfRenderer()

' Convert from URL — useful when migrating from wkhtmltopdf URL-based workflows
Dim pdf = renderer.RenderUrlAsPdf("https://localhost:5001/reports/quarterly")
pdf.SaveAs("report.pdf")

' Convert from local HTML file
Dim pdfFromFile = renderer.RenderHtmlFileAsPdf("templates/invoice.html")
pdfFromFile.SaveAs("invoice.pdf")