java - 将 PDF 评论提取为 HTML

Question

输入带注释的PDF文档

我有一个 PDF 文档，其中包含突出显示和突出显示的评论(“我的评论”)(downlload)。

期望的输出

我想将 PDF 转换为文本，注释位于 标签中，如下所示:

ONE TWO THREE    
FOUR <b id="my comment">FIVE</b> SIX SEVEN

问题

谁能帮我实现方法:

private double getDistance(PDAnnotation ann, TextPosition firstProsition) {...}

或方法

private boolean isTextAnnotated()

判断注解ann是否在正文的位置？如果可能的话，也可以很好地确定评论的文本位置。

JAVA代码

无论如何，我迷失了如何确定注释是否与当前处理的文本相关。我也不知道是否可以识别文本的确切部分。

                PDFParser parser = new PDFParser(new FileInputStream(file));
                parser.parse();
                cosDoc = parser.getDocument();

                pdfStripper = new PDFTextStripper()
                {
                    List<PDAnnotation> la;
                    private boolean closeWithEnd;
                    @Override
                    protected void startPage(PDPage page) throws IOException
                    {
                        la = page.getAnnotations(); // init pages
                        startOfLine = true;
                        super.startPage(page);
                    }

                    @Override
                    protected void writeLineSeparator() throws IOException
                    {
                        startOfLine = true;
                        super.writeLineSeparator();
                        if(closeWithEnd) {
                            writeString(" </b> ");
                        }
                    }

                    @Override
                    protected void writeString(String text, List<TextPosition> textPositions) throws IOException
                    {
                        if (startOfLine)
                        {
                            TextPosition firstProsition = textPositions.get(0);
                            PDAnnotation ann;
                            if((ann = isTextAnnotated(firstProsition, text)) != null) {
                                writeString(" <b id='"+ann.getAnnotationName()+"'> ");
                                closeWithEnd = true;
                            } else {
                                closeWithEnd = false;
                            }
                            startOfLine = false;
                        }
                        super.writeString(text+" ", textPositions);
                    }
                    private PDAnnotation isTextAnnotated(TextPosition firstProsition, String text) {
                        for (PDAnnotation ann : la) {
                            System.out.println(text+" ------------- "+getDistance(ann, firstProsition));
                        }
                        return null;
                    }
                    private double getDistance(PDAnnotation ann, TextPosition firstProsition) {
                        TODO - how to get distance
                        return 0.0;
                    }
                    boolean startOfLine = true;
                };

                pdDoc = new PDDocument(cosDoc);
                pdfStripper.setStartPage(0);
                pdfStripper.setEndPage(pdDoc.getNumberOfPages());
                String parsedText = pdfStripper.getText(pdDoc);

Maven 依赖项

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>3.8.1</version>
  <scope>test</scope>
</dependency>

<!-- http://mvnrepository.com/artifact/org.apache.pdfbox/pdfbox -->
<dependency>
    <groupId>org.apache.pdfbox</groupId>
    <artifactId>pdfbox</artifactId>
    <version>1.8.10</version>
</dependency>

<!-- http://mvnrepository.com/artifact/org.apache.tika/tika-core -->
<dependency>
    <groupId>org.apache.tika</groupId>
    <artifactId>tika-core</artifactId>
    <version>1.13</version>
</dependency>

<!-- http://mvnrepository.com/artifact/commons-io/commons-io -->
<dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.4</version>
</dependency>


<!-- http://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

<dependency>
    <groupId>info.debatty</groupId>
    <artifactId>java-string-similarity</artifactId>
    <version>RELEASE</version>
</dependency>

<dependency>
  <groupId>org.apache.opennlp</groupId>
  <artifactId>opennlp-tools</artifactId>
  <version>1.6.0</version>
</dependency>

Answer 1

可以得到注解矩形，看看它是否同时包含每个文本位置的左上角和右下角。由于 writeString 包含多个字符，您需要单独检查每个字符，因为注释可能只覆盖字符的一个子集。注释也可以换行，因此如果需要关闭 html 标记，您需要在页面末尾(而不是每行末尾)进行检查。请注意，您从注释中获得的矩形位于 PDF 空间中。但是您从 TextPosition 获得的坐标是在 java 空间中。因此，当您选中 Rectangle.contains 时，您需要将文本位置坐标转换为 PDF 空间。

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.List;

import org.apache.pdfbox.cos.COSDocument;
import org.apache.pdfbox.pdfparser.PDFParser;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDPage;
import org.apache.pdfbox.pdmodel.interactive.annotation.PDAnnotation;
import org.apache.pdfbox.util.PDFTextStripper;
import org.apache.pdfbox.util.TextPosition;

public class MyPDFTextStripper extends PDFTextStripper
{
    public MyPDFTextStripper() throws IOException
    {
        super();
        // TODO Auto-generated constructor stub
    }

    PDPage currentPage;
    List<PDAnnotation> pageAnnotations;
    private boolean needsEndTag;
    boolean startOfLine = true;

    @Override
    protected void startPage(PDPage page) throws IOException
    {
        currentPage = page;
        pageAnnotations = currentPage.getAnnotations();
        super.startPage(page);
    }

    @Override
    protected void writeString(String text, List<TextPosition> textPositions) throws IOException
    {
        StringBuilder newText = new StringBuilder();
        PDAnnotation currentAnnot = null;
        for (TextPosition textPosition : textPositions)
        {
            PDAnnotation annotation = getAnnotation(textPosition);
            if (annotation != null)
            {
                if (currentAnnot == null)
                {
                    // if the currentAnnot is null, start a new annotation
                    newText.append("<b id='" + annotation.getAnnotationName() + "'>");
                }
                else if (!currentAnnot.getAnnotationName().equals(annotation.getAnnotationName()))
                {
                    // if the current Annot is different, end it and start a new
                    // one
                    newText.append("</b><b id='" + annotation.getAnnotationName() + "'>");
                }
                // remember this in case the annotation wraps lines
                needsEndTag = true;
                currentAnnot = annotation;
            }
            else if (currentAnnot != null)
            {
                // if no new annotation is associated with the text, but there used to be, close the tag
                newText.append("</b>");
                currentAnnot = null;
                needsEndTag = false;
            }
            newText.append(textPosition.getCharacter());
        }
        super.writeString(newText.toString(), textPositions);
    }

    private PDAnnotation getAnnotation(TextPosition textPosition)
    {
        float textX1 = textPosition.getX();
        // Translate the y coordinate to PDF Space
        float textY1 = currentPage.findMediaBox().getHeight() - textPosition.getY();
        float textX2 = textX1 + textPosition.getWidth();
        float textY2 = textY1 + textPosition.getHeight();

        for (PDAnnotation annotation : pageAnnotations)
        {
            if (annotation.getRectangle().contains(textX1, textY1) && annotation.getRectangle().contains(textX2, textY2))
            {
                return annotation;
            }
        }
        return null;
    }

    @Override
    public String getPageEnd()
    {
        // if the annotation wraps lines and extends to the end of the document, need to add the end tag
        if (needsEndTag)
        {
            return "</b>" + super.getPageEnd();
        }
        return super.getPageEnd();
    }

    public static void main(String[] args) throws Exception
    {
        File file = new File(args[0]);
        PDFParser parser = new PDFParser(new FileInputStream(file));
        parser.parse();
        COSDocument cosDoc = parser.getDocument();

        MyPDFTextStripper pdfStripper = new MyPDFTextStripper();

        PDDocument pdDoc = new PDDocument(cosDoc);
        pdfStripper.setStartPage(0);
        pdfStripper.setEndPage(pdDoc.getNumberOfPages());
        String parsedText = pdfStripper.getText(pdDoc);
        System.out.println(parsedText);
    }
}