C# 在 .Net 中阅读 PDF 文档
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Reading PDF documents in .Net
提问by JRoppert
Is there an open source library that will help me with reading/parsing PDF documents in .Net/C#?
是否有一个开源库可以帮助我阅读/解析 .Net/C# 中的 PDF 文档？
采纳答案by Brock Nusser
Since this question was last answered in 2008, iTextSharp has improved their api dramatically. If you download the latest version of their api from http://sourceforge.net/projects/itextsharp/, you can use the following snippet of code to extract all text from a pdf into a string.
自从上次回答这个问题是在 2008 年，iTextSharp 极大地改进了他们的 api。如果您从http://sourceforge.net/projects/itextsharp/下载最新版本的 api ，您可以使用以下代码片段将 pdf 中的所有文本提取为字符串。
using iTextSharp.text.pdf;
using iTextSharp.text.pdf.parser;
namespace PdfParser
{
public static class PdfTextExtractor
{
public static string pdfText(string path)
{
PdfReader reader = new PdfReader(path);
string text = string.Empty;
for(int page = 1; page <= reader.NumberOfPages; page++)
{
text += PdfTextExtractor.GetTextFromPage(reader,page);
}
reader.Close();
return text;
}
}
}
回答by Alex Fort
You could look into this: http://www.codeproject.com/KB/showcase/pdfrasterizer.aspxIt's not completely free, but it looks very nice.
你可以看看这个： http://www.codeproject.com/KB/showcase/pdfrasterizer.aspx这不是完全免费的，但它看起来很不错。
Alex
亚历克斯
回答by Ilya Kochetov
回答by Cetra
回答by Cetra
iText is the best library I know. Originally written in Java, there is a .NET port as well.
iText 是我所知道的最好的图书馆。最初是用 Java 编写的，还有一个 .NET 端口。
回答by Ben McEvoy
http://www.c-sharpcorner.com/UploadFile/psingh/PDFFileGenerator12062005235236PM/PDFFileGenerator.aspxis open source and may be a good starting point for you.
http://www.c-sharpcorner.com/UploadFile/psingh/PDFFileGenerator12062005235236PM/PDFFileGenerator.aspx是开源的，可能是您一个很好的起点。
回答by ceetheman
iTextSharpis the best bet. Used it to make a spider for lucene.Net so that it could crawl PDF.
iTextSharp是最好的选择。用它为 lucene.Net 制作蜘蛛，以便它可以抓取 PDF。
using System;
using System.IO;
using iTextSharp.text.pdf;
using System.Text.RegularExpressions;
namespace Spider.Utils
{
/// <summary>
/// Parses a PDF file and extracts the text from it.
/// </summary>
public class PDFParser
{
/// BT = Beginning of a text object operator
/// ET = End of a text object operator
/// Td move to the start of next line
/// 5 Ts = superscript
/// -5 Ts = subscript
#region Fields
#region _numberOfCharsToKeep
/// <summary>
/// The number of characters to keep, when extracting text.
/// </summary>
private static int _numberOfCharsToKeep = 15;
#endregion
#endregion
#region ExtractText
/// <summary>
/// Extracts a text from a PDF file.
/// </summary>
/// <param name="inFileName">the full path to the pdf file.</param>
/// <param name="outFileName">the output file name.</param>
/// <returns>the extracted text</returns>
public bool ExtractText(string inFileName, string outFileName)
{
StreamWriter outFile = null;
try
{
// Create a reader for the given PDF file
PdfReader reader = new PdfReader(inFileName);
//outFile = File.CreateText(outFileName);
outFile = new StreamWriter(outFileName, false, System.Text.Encoding.UTF8);
Console.Write("Processing: ");
int totalLen = 68;
float charUnit = ((float)totalLen) / (float)reader.NumberOfPages;
int totalWritten = 0;
float curUnit = 0;
for (int page = 1; page <= reader.NumberOfPages; page++)
{
outFile.Write(ExtractTextFromPDFBytes(reader.GetPageContent(page)) + " ");
// Write the progress.
if (charUnit >= 1.0f)
{
for (int i = 0; i < (int)charUnit; i++)
{
Console.Write("#");
totalWritten++;
}
}
else
{
curUnit += charUnit;
if (curUnit >= 1.0f)
{
for (int i = 0; i < (int)curUnit; i++)
{
Console.Write("#");
totalWritten++;
}
curUnit = 0;
}
}
}
if (totalWritten < totalLen)
{
for (int i = 0; i < (totalLen - totalWritten); i++)
{
Console.Write("#");
}
}
return true;
}
catch
{
return false;
}
finally
{
if (outFile != null) outFile.Close();
}
}
#endregion
#region ExtractTextFromPDFBytes
/// <summary>
/// This method processes an uncompressed Adobe (text) object
/// and extracts text.
/// </summary>
/// <param name="input">uncompressed</param>
/// <returns></returns>
public string ExtractTextFromPDFBytes(byte[] input)
{
if (input == null || input.Length == 0) return "";
try
{
string resultString = "";
// Flag showing if we are we currently inside a text object
bool inTextObject = false;
// Flag showing if the next character is literal
// e.g. '\' to get a '\' character or '\(' to get '('
bool nextLiteral = false;
// () Bracket nesting level. Text appears inside ()
int bracketDepth = 0;
// Keep previous chars to get extract numbers etc.:
char[] previousCharacters = new char[_numberOfCharsToKeep];
for (int j = 0; j < _numberOfCharsToKeep; j++) previousCharacters[j] = ' ';
for (int i = 0; i < input.Length; i++)
{
char c = (char)input[i];
if (input[i] == 213)
c = "'".ToCharArray()[0];
if (inTextObject)
{
// Position the text
if (bracketDepth == 0)
{
if (CheckToken(new string[] { "TD", "Td" }, previousCharacters))
{
resultString += "\n\r";
}
else
{
if (CheckToken(new string[] { "'", "T*", "\"" }, previousCharacters))
{
resultString += "\n";
}
else
{
if (CheckToken(new string[] { "Tj" }, previousCharacters))
{
resultString += " ";
}
}
}
}
// End of a text object, also go to a new line.
if (bracketDepth == 0 &&
CheckToken(new string[] { "ET" }, previousCharacters))
{
inTextObject = false;
resultString += " ";
}
else
{
// Start outputting text
if ((c == '(') && (bracketDepth == 0) && (!nextLiteral))
{
bracketDepth = 1;
}
else
{
// Stop outputting text
if ((c == ')') && (bracketDepth == 1) && (!nextLiteral))
{
bracketDepth = 0;
}
else
{
// Just a normal text character:
if (bracketDepth == 1)
{
// Only print out next character no matter what.
// Do not interpret.
if (c == '\' && !nextLiteral)
{
resultString += c.ToString();
nextLiteral = true;
}
else
{
if (((c >= ' ') && (c <= '~')) ||
((c >= 128) && (c < 255)))
{
resultString += c.ToString();
}
nextLiteral = false;
}
}
}
}
}
}
// Store the recent characters for
// when we have to go back for a checking
for (int j = 0; j < _numberOfCharsToKeep - 1; j++)
{
previousCharacters[j] = previousCharacters[j + 1];
}
previousCharacters[_numberOfCharsToKeep - 1] = c;
// Start of a text object
if (!inTextObject && CheckToken(new string[] { "BT" }, previousCharacters))
{
inTextObject = true;
}
}
return CleanupContent(resultString);
}
catch
{
return "";
}
}
private string CleanupContent(string text)
{
string[] patterns = { @"\\(", @"\\)", @"\226", @"\222", @"\223", @"\224", @"\340", @"\342", @"\344", @"\300", @"\302", @"\304", @"\351", @"\350", @"\352", @"\353", @"\311", @"\310", @"\312", @"\313", @"\362", @"\364", @"\366", @"\322", @"\324", @"\326", @"\354", @"\356", @"\357", @"\314", @"\316", @"\317", @"\347", @"\307", @"\371", @"\373", @"\374", @"\331", @"\333", @"\334", @"\256", @"\231", @"\253", @"\273", @"\251", @"\221"};
string[] replace = { "(", ")", "-", "'", "\"", "\"", "à", "a", "?", "à", "?", "?", "é", "è", "ê", "?", "é", "è", "ê", "?", "ò", "?", "?", "ò", "?", "?", "ì", "?", "?", "ì", "?", "?", "?", "?", "ù", "?", "ü", "ù", "?", "ü", "?", "?", "?", "?", "?", "'" };
for (int i = 0; i < patterns.Length; i++)
{
string regExPattern = patterns[i];
Regex regex = new Regex(regExPattern, RegexOptions.IgnoreCase);
text = regex.Replace(text, replace[i]);
}
return text;
}
#endregion
#region CheckToken
/// <summary>
/// Check if a certain 2 character token just came along (e.g. BT)
/// </summary>
/// <param name="tokens">the searched token</param>
/// <param name="recent">the recent character array</param>
/// <returns></returns>
private bool CheckToken(string[] tokens, char[] recent)
{
foreach (string token in tokens)
{
if ((recent[_numberOfCharsToKeep - 3] == token[0]) &&
(recent[_numberOfCharsToKeep - 2] == token[1]) &&
((recent[_numberOfCharsToKeep - 1] == ' ') ||
(recent[_numberOfCharsToKeep - 1] == 0x0d) ||
(recent[_numberOfCharsToKeep - 1] == 0x0a)) &&
((recent[_numberOfCharsToKeep - 4] == ' ') ||
(recent[_numberOfCharsToKeep - 4] == 0x0d) ||
(recent[_numberOfCharsToKeep - 4] == 0x0a))
)
{
return true;
}
}
return false;
}
#endregion
}
}
回答by Kuvo
aspose pdfworks pretty well. then again, you have to pay for it
aspose pdf效果很好。再说一次，你必须为此付出代价
回答by ShravankumarKumar
public string ReadPdfFile(object Filename, DataTable ReadLibray)
{
PdfReader reader2 = new PdfReader((string)Filename);
string strText = string.Empty;
for (int page = 1; page <= reader2.NumberOfPages; page++)
{
ITextExtractionStrategy its = new iTextSharp.text.pdf.parser.SimpleTextExtractionStrategy();
PdfReader reader = new PdfReader((string)Filename);
String s = PdfTextExtractor.GetTextFromPage(reader, page, its);
s = Encoding.UTF8.GetString(ASCIIEncoding.Convert(Encoding.Default, Encoding.UTF8, Encoding.Default.GetBytes(s)));
strText = strText + s;
reader.Close();
}
return strText;
}
回答by Bobrovsky
Have a look at Docotic.Pdf library. It does not require you to make source code of your application open (like iTextSharp with viral AGPL 3 license, for example).
看看Docotic.Pdf 库。它不需要您打开应用程序的源代码（例如 iTextSharp 与病毒式 AGPL 3 许可证）。
Docotic.Pdf can be used to read PDF files and extract text with or without formatting. Please have a look at the sample that shows how to extract text from PDFs.
Docotic.Pdf 可用于阅读 PDF 文件并提取带或不带格式的文本。请查看显示如何从 PDF 中提取文本的示例。
Disclaimer: I work for Bit Miracle, vendor of the library.
免责声明：我为该库的供应商 Bit Miracle 工作。
