http://hi.baidu.com/br_yan/item/ddacbefd568d8157c9f337d4
HTML轉PDF(C#---itextsharp)
一、 需求:將HTML轉PDF列印。Web項目中總是有這樣的需求,很是讓人苦惱。
二、 分析:如何完成這個工作?
1、 需要解析HTML,然後利用itextsharp繪製pdf文檔。解析HTML是一個很難完成的任務,各個瀏覽器對HTML的解析五花八門就知道這不好解決。這條路不好走,但也是可以完成的,通過webbrowser類可以解析HTML擷取各對象的位置,然後繪製到pdf中。方法是可行,其中的複雜度不小。
2、 將HTML儲存為圖片,然後插入到pdf文檔中,這裡將介紹這種方法。隨之而來的問題:如何將HTML儲存為圖片呢?
三、 解決辦法:
1、 將HTML儲存為圖片:需要用到webbrower類,將指定的HTML載入webbrower,然後調用其DrawToBitmap方法擷取圖片。代碼如下:
private System.Drawing.Bitmap bitmap;
private string url;
private int w = 760, h = 900;//A4紙張對應的解析度大概就是760*900
public void setBitmap()
{
using (WebBrowser wb = new WebBrowser())
{
wb.Width = w;
wb.Height = h;
wb.ScrollBarsEnabled = false;
wb.Navigate(url);
//確保頁面被解析完全
while (wb.ReadyState != WebBrowserReadyState.Complete)
{
System.Windows.Forms.Application.DoEvents();
}
bitmap = new System.Drawing.Bitmap(w, h);
wb.DrawToBitmap(bitmap, new System.Drawing.Rectangle(0, 0, w, h));
wb.Dispose();
}
}
2、 如何調用WebBrowser?直接在web頁面用的話,會出現錯誤:“當前線程不在單一執行緒 Apartment中,因此無法執行個體化 ActiveX 控制項”。這需要建立一個單一執行緒 Apartment,在此單元內調用,方法如下while迴圈確保線程執行完成,也就是確保bitmap已經被初始化了:
url = Server.MapPath("s.html");
Thread thread = new Thread(new ThreadStart(setBitmap));
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
while (thread.IsAlive)
Thread.Sleep(100);
bitmap.Save(Server.MapPath("t.bmp"));
3、 插入圖片到PDF:
iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(bitmap, System.Drawing.Imaging.ImageFormat.Bmp);
img.ScalePercent(75);//pdf解析度要大一些,需要縮小以恢複正常PDF是96DPI,IE是72DPI
doc.Add(img);
四、 完整代碼如下:
using System;
using System.Data;
using System.Web;
using iTextSharp.text.pdf;
using iTextSharp.text;
using System.IO;
using System.Windows.Forms;
using System.Threading;
public partial class HTML2PDF : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
CreatPdf();
}
private System.Drawing.Bitmap bitmap;
private string url;
private int w = 760, h = 900;
public void setBitmap()
{
using (WebBrowser wb = new WebBrowser())
{
wb.Width = w;
wb.Height = h;
wb.ScrollBarsEnabled = false;
wb.Navigate(url);
//確保頁面被解析完全
while (wb.ReadyState != WebBrowserReadyState.Complete)
{
System.Windows.Forms.Application.DoEvents();
}
bitmap = new System.Drawing.Bitmap(w, h);
wb.DrawToBitmap(bitmap, new System.Drawing.Rectangle(0, 0, w, h));
wb.Dispose();
}
}
private void CreatPdf()
{
Document doc = new Document(PageSize.A4, 9, 18, 36, 36);//左右上下
MemoryStream ms = new MemoryStream();
try
{
PdfWriter writer = PdfWriter.GetInstance(doc, ms);
writer.CloseStream = false;
doc.Open();
url = Server.MapPath("s.html");
Thread thread = new Thread(new ThreadStart(setBitmap));
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
while (thread.IsAlive)
Thread.Sleep(100);
bitmap.Save(Server.MapPath("t.bmp"));
iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(bitmap, System.Drawing.Imaging.ImageFormat.Bmp);
img.ScalePercent(75);//560 630
doc.Add(img);
}
catch (Exception err)
{
throw new Exception(err.Message);
}
finally
{
doc.Close();
using (FileStream fs = new FileStream(Server.MapPath("out.pdf"), FileMode.Create))
{
ms.Position = 0;
byte[] bit = new byte[ms.Length];
ms.Read(bit, 0, (int)ms.Length);
fs.Write(bit, 0, bit.Length);
}
ViewPdf(ms);
}
}
private void ViewPdf(Stream fs)
{
Response.Clear();
//中文名的話
//Response.AppendHeader("Content-Disposition", "attachment;filename=" +
// HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8) + ";charset=GB2312");
Response.AddHeader("Content-Disposition", "attachment;FileName=out.pdf");
Response.AddHeader("Content-Length", fs.Length.ToString());
Response.ContentType = "application/pdf";
long fileLength = fs.Length;
int size = 10240;//10K一--分塊下載,10K為1塊
byte[] readData = new byte[size];
if (size > fileLength)
size = Convert.ToInt32(fileLength);
long fPos = 0;
bool isEnd = false;
while (!isEnd)
{
if ((fPos + size) >= fileLength)
{
size = Convert.ToInt32(fileLength - fPos);
isEnd = true;
}
readData = new byte[size];
fs.Position = fPos;
fs.Read(readData, 0, size);
Response.BinaryWrite(readData);
Response.OutputStream.Flush();
fPos += size;
}
fs.Close();
Response.OutputStream.Close();
Response.End();//非常重要,沒有這句的話,頁面的HTML代碼將會儲存到檔案中
Response.Close();
}
}
五、至此工作完成,轉載註明出處,謝謝。
六、2009-12-23補充說明:增加pdf列印清晰度,對於圖片,要想在pdf上列印的更清晰需要產生大圖,然後等比例縮放存放在pdf裡面,這樣pdf列印出來的圖會很清晰,基本是縮放比例越大越清晰,對於圖形報表特別有效。對於本文介紹的方法,也可以產生大圖縮放到pdf裡面。