使用itextsharp（或任何c＃pdf库），我需要打开一个PDF，用实际值替换一些占位符文本，并将其作为byte []返回。
有人可以建议怎么做吗？我已经看了一下itext文档，无法弄清楚从哪里开始。到目前为止，我仍然坚持如何将源PDF文件从PDFReader获取到Document对象，我认为我可能以错误的方式接近它。
非常感谢
答案 0 :(得分：5)
最后，我使用PDFescape打开现有的PDF文件，并将一些表单字段放在我需要放置字段的位置，然后再次保存以创建我的PDF文件。
然后我找到了关于如何替换表单字段的博客文章：
一切都很好用！这是代码：
public static byte[] Generate()
{
var templatePath = HttpContext.Current.Server.MapPath("~/my_template.pdf");
// Based on:
// http://www.johnnycode.com/blog/2010/03/05/using-a-template-to-programmatically-create-pdfs-with-c-and-itextsharp/
var reader = new PdfReader(templatePath);
var outStream = new MemoryStream();
var stamper = new PdfStamper(reader, outStream);
var form = stamper.AcroFields;
var fieldKeys = form.Fields.Keys;
foreach (string fieldKey in fieldKeys)
{
if (form.GetField(fieldKey) == "MyTemplatesOriginalTextFieldA")
form.SetField(fieldKey, "1234");
if (form.GetField(fieldKey) == "MyTemplatesOriginalTextFieldB")
form.SetField(fieldKey, "5678");
}
// "Flatten" the form so it wont be editable/usable anymore
stamper.FormFlattening = true;
stamper.Close();
reader.Close();
return outStream.ToArray();
}
答案 1 :(得分：1)
不幸的是，我一直在寻找类似的东西，但无法弄明白。以下是关于我得到的，也许你可以用这个作为起点。问题是PDF实际上并没有保存文本，而是使用查找表和其他一些神秘的魔法。这个方法读取页面的字节值并尝试转换为字符串，但据我所知，它只能做英文并且会遗漏一些特殊字符，所以我放弃了我的项目并继续前进。
string contents = string.Empty();
Document doc = new Document();
PdfReader reader = new PdfReader("pathToPdf.pdf");
using (MemoryStream memoryStream = new MemoryStream())
{
PdfWriter writer = PdfWriter.GetInstance(doc, memoryStream);
doc.Open();
PdfContentByte cb = writer.DirectContent;
for (int p = 1; p <= reader.NumberOfPages; p++)
{
// add page from reader
doc.SetPageSize(reader.GetPageSize(p));
doc.NewPage();
// pickup here something like this:
byte[] bt = reader.GetPageContent(p);
contents = ExtractTextFromPDFBytes(bt);
if (contents.IndexOf("something")!=-1)
{
// make your own pdf page and add to cb (contentbyte)
}
else
{
PdfImportedPage page = writer.GetImportedPage(reader, p);
int rot = reader.GetPageRotation(p);
if (rot == 90 || rot == 270)
cb.AddTemplate(page, 0, -1.0F, 1.0F, 0, 0, reader.GetPageSizeWithRotation(p).Height);
else
cb.AddTemplate(page, 1.0F, 0, 0, 1.0F, 0, 0);
}
}
reader.Close();
doc.Close();
File.WriteAllBytes("pathToOutputOrSamePathToOverwrite.pdf", memoryStream.ToArray());
这取自this site。
private 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 (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)
{
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 resultString;
}
catch
{
return "";
}
}
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;
}
答案 2 :(得分：0)
我这里有一个python脚本，可替换PDF中的某些文本：
import re
import sys
import zlib
# Module to find and replace text in PDF files
#
# Usage:
# python pdf_replace.py <input_filename> <text_to_find> <text_to_replace> <output_filename>
#
# @author Ionox0
input_filename = sys.argv[1]
text_to_find = sys.argv[2]
text_to_replace = sys.argv[3]
output_filename sys.argv[4]
pdf = open(input_filename, "rb").read()
# Create a copy of the PDF content to make edits to
pdf_copy = pdf[0:]
# Search for stream objects with text to replace
stream = re.compile(r'.*?FlateDecode.*?stream(.*?)endstream', re.S)
for s in stream.findall(pdf):
s = s.strip('\r\n')
try:
text = zlib.decompress(s)
if text_to_find in text:
print('Found match:')
print(text)
text = text.replace(text_to_find, text_to_replace)
pdf_copy = pdf_copy.replace(s, zlib.compress(text))
except:
pass
with open(output_filename, 'wb') as out:
out.write(pdf_copy)