Pdf

# PDF Processing Guide

## 概述

本指南介绍了使用 Python 库和命令行工具进行基本 PDF 处理的操作。有关高级功能、JavaScript 库和详细示例，请参阅 reference.md。如果您需要填写 PDF 表单，请阅读 forms.md 并按照其说明操作。

## 快速开始

```python from pypdf import PdfReader, PdfWriter

# Read a PDF reader = PdfReader("document.pdf") print(f"Pages: {len(reader.pages)}")

# Extract text text = "" for page in reader.pages: text += page.extract_text() ```

## Python 库

### pypdf - 基本操作

#### 合并 PDF ```python from pypdf import PdfWriter, PdfReader

writer = PdfWriter() for pdf_file in ["doc1.pdf", "doc2.pdf", "doc3.pdf"]: reader = PdfReader(pdf_file) for page in reader.pages: writer.add_page(page)

with open("merged.pdf", "wb") as output: writer.write(output) ```

#### 拆分 PDF ```python reader = PdfReader("input.pdf") for i, page in enumerate(reader.pages): writer = PdfWriter() writer.add_page(page) with open(f"page_{i+1}.pdf", "wb") as output: writer.write(output) ```

#### 提取元数据 ```python reader = PdfReader("document.pdf") meta = reader.metadata print(f"Title: {meta.title}") print(f"Author: {meta.author}") print(f"Subject: {meta.subject}") print(f"Creator: {meta.creator}") ```

#### 旋转页面 ```python reader = PdfReader("input.pdf") writer = PdfWriter()

page = reader.pages[0] page.rotate(90) # Rotate 90 degrees clockwise writer.add_page(page)

with open("rotated.pdf", "wb") as output: writer.write(output) ```

### pdfplumber - 文本和表格提取

#### 提取带布局的文本 ```python import pdfplumber

with pdfplumber.open("document.pdf") as pdf: for page in pdf.pages: text = page.extract_text() print(text) ```

#### 提取表格 ```python with pdfplumber.open("document.pdf") as pdf: for i, page in enumerate(pdf.pages): tables = page.extract_tables() for j, table in enumerate(tables): print(f"Table {j+1} on page {i+1}:") for row in table: print(row) ```

#### 高级表格提取 ```python import pandas as pd

with pdfplumber.open("document.pdf") as pdf: all_tables = [] for page in pdf.pages: tables = page.extract_tables() for table in tables: if table: # Check if table is not empty df = pd.DataFrame(table[1:], columns=table[0]) all_tables.append(df)

# Combine all tables if all_tables: combined_df = pd.concat(all_tables, ignore_index=True) combined_df.to_excel("extracted_tables.xlsx", index=False) ```

### reportlab - 创建 PDF

#### 基本 PDF 创建 ```python from reportlab.lib.pagesizes import letter from reportlab.pdfgen import canvas

c = canvas.Canvas("hello.pdf", pagesize=letter) width, height = letter

# Add text c.drawString(100, height - 100, "Hello World!") c.drawString(100, height - 120, "This is a PDF created with reportlab")

# Add a line c.line(100, height - 140, 400, height - 140)

# Save c.save() ```

#### 创建多页 PDF ```python from reportlab.lib.pagesizes import letter from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer, PageBreak from reportlab.lib.styles import getSampleStyleSheet

doc = SimpleDocTemplate("report.pdf", pagesize=letter) styles = getSampleStyleSheet() story = []

# Add content title = Paragraph("Report Title", styles['Title']) story.append(title) story.append(Spacer(1, 12))

body = Paragraph("This is the body of the report. " * 20, styles['Normal']) story.append(body) story.append(PageBreak())

# Page 2 story.append(Paragraph("Page 2", styles['Heading1'])) story.append(Paragraph("Content for page 2", styles['Normal']))

# Build PDF doc.build(story) ```

## 命令行工具

### pdftotext (poppler-utils) ```bash # Extract text pdftotext input.pdf output.txt

# Extract text preserving layout pdftotext -layout input.pdf output.txt

# Extract specific pages pdftotext -f 1 -l 5 input.pdf output.txt # Pages 1-5 ```

### qpdf ```bash # Merge PDFs qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf

# Split pages qpdf input.pdf --pages . 1-5 -- pages1-5.pdf qpdf input.pdf --pages . 6-10 -- pages6-10.pdf

# Rotate pages qpdf input.pdf output.pdf --rotate=+90:1 # Rotate page 1 by 90 degrees

# Remove password qpdf --password=mypassword --decrypt encrypted.pdf decrypted.pdf ```

### pdftk (如果可用) ```bash # Merge pdftk file1.pdf file2.pdf cat output merged.pdf

# Split pdftk input.pdf burst

# Rotate pdftk input.pdf rotate 1east output rotated.pdf ```

## 常见任务

### 从扫描的 PDF 中提取文本 ```python # Requires: pip install pytesseract pdf2image import pytesseract from pdf2image import convert_from_path

# Convert PDF to images images = convert_from_path('scanned.pdf')

# OCR each page text = "" for i, image in enumerate(images): text += f"Page {i+1}:\n" text += pytesseract.image_to_string(image) text += "\n\n"

print(text) ```

### 添加水印 ```python from pypdf import PdfReader, PdfWriter

# Create watermark (or load existing) watermark = PdfReader("watermark.pdf").pages[0]

# Apply to all pages reader = PdfReader("document.pdf") writer = PdfWriter()

for page in reader.pages: page.merge_page(watermark) writer.add_page(page)

with open("watermarked.pdf", "wb") as output: writer.write(output) ```

### 提取图像 ```bash # Using pdfimages (poppler-utils) pdfimages -j input.pdf output_prefix

# This extracts all images as output_prefix-000.jpg, output_prefix-001.jpg, etc. ```

### 密码保护 ```python from pypdf import PdfReader, PdfWriter

reader = PdfReader("input.pdf") writer = PdfWriter()

for page in reader.pages: writer.add_page(page)

# Add password writer.encrypt("userpassword", "ownerpassword")

with open("encrypted.pdf", "wb") as output: writer.write(output) ```

## 快速参考

| 任务 | 推荐工具 | 命令/代码 | |------|-----------|--------------| | 合并 PDF | pypdf | `writer.add_page(page)` | | 拆分 PDF | pypdf | 每个文件一页 | | 提取文本 | pdfplumber | `page.extract_text()` | | 提取表格 | pdfplumber | `page.extract_tables()` | | 创建 PDF | reportlab | Canvas 或 Platypus | | 命令行合并 | qpdf | `qpdf --empty --pages ...` | | 扫描 PDF OCR | pytesseract | 先转换为图像 | | 填写 PDF 表单 | pdf-lib 或 pypdf (参见 forms.md) | 参见 forms.md |

## 后续步骤

- 有关高级 pypdfium2 用法，请参阅 reference.md - 有关 JavaScript 库 (pdf-lib)，请参阅 reference.md - 如果您需要填写 PDF 表单，请遵循 forms.md 中的说明 - 有关故障排除指南，请参阅 reference.md