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PDFBox:提取文本时保持PDF结构

pdfbox java

Leor · 技术社区 · 9 年前

我试图从一个充满表格的PDF中提取文本。在某些情况下,列为空。当我从PDF中提取文本时,空白列被跳过并替换为空白,因此,我的常规表达式无法判断出在这个位置有一个没有信息的列。

我们可以看到,在提取的文本中不尊重列

我从PDF中提取文本的代码示例:

PDFTextStripper reader = new PDFTextStripper();
            reader.setSortByPosition(true);
            reader.setStartPage(page);
            reader.setEndPage(page);
            String st = reader.getText(document);
            List<String> lines = Arrays.asList(st.split(System.getProperty("line.separator")));

非常感谢。

1 回复 | 直到 9 年前

mkl 9 年前

(这原本是 the answer (dated Feb 6 '15) to another question

在评论中,OP对解决方案表现出兴趣 扩展PDFBox PDFTextStripper 返回试图反映PDF文件布局的文本行 这可能有助于解决眼前的问题。

这一类可以证明这一点:

public class LayoutTextStripper extends PDFTextStripper
{
    public LayoutTextStripper() throws IOException
    {
        super();
    }

    @Override
    protected void startPage(PDPage page) throws IOException
    {
        super.startPage(page);
        cropBox = page.findCropBox();
        pageLeft = cropBox.getLowerLeftX();
        beginLine();
    }

    @Override
    protected void writeString(String text, List<TextPosition> textPositions) throws IOException
    {
        float recentEnd = 0;
        for (TextPosition textPosition: textPositions)
        {
            String textHere = textPosition.getCharacter();
            if (textHere.trim().length() == 0)
                continue;

            float start = textPosition.getTextPos().getXPosition();
            boolean spacePresent = endsWithWS | textHere.startsWith(" ");

            if (needsWS | spacePresent | Math.abs(start - recentEnd) > 1)
            {
                int spacesToInsert = insertSpaces(chars, start, needsWS & !spacePresent);

                for (; spacesToInsert > 0; spacesToInsert--)
                {
                    writeString(" ");
                    chars++;
                }
            }

            writeString(textHere);
            chars += textHere.length();

            needsWS = false;
            endsWithWS = textHere.endsWith(" ");
            try
            {
                recentEnd = getEndX(textPosition);
            }
            catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException | SecurityException e)
            {
                throw new IOException("Failure retrieving endX of TextPosition", e);
            }
        }
    }

    @Override
    protected void writeLineSeparator() throws IOException
    {
        super.writeLineSeparator();
        beginLine();
    }

    @Override
    protected void writeWordSeparator() throws IOException
    {
        needsWS = true;
    }

    void beginLine()
    {
        endsWithWS = true;
        needsWS = false;
        chars = 0;
    }

    int insertSpaces(int charsInLineAlready, float chunkStart, boolean spaceRequired)
    {
        int indexNow = charsInLineAlready;
        int indexToBe = (int)((chunkStart - pageLeft) / fixedCharWidth);
        int spacesToInsert = indexToBe - indexNow;
        if (spacesToInsert < 1 && spaceRequired)
            spacesToInsert = 1;

        return spacesToInsert;
    }

    float getEndX(TextPosition textPosition) throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, SecurityException
    {
        Field field = textPosition.getClass().getDeclaredField("endX");
        field.setAccessible(true);
        return field.getFloat(textPosition);
    }

    public float fixedCharWidth = 3;

    boolean endsWithWS = true;
    boolean needsWS = false;
    int chars = 0;

    PDRectangle cropBox = null;
    float pageLeft = 0;
}

它的用法如下:

PDDocument document = PDDocument.load(PDF);

LayoutTextStripper stripper = new LayoutTextStripper();
stripper.setSortByPosition(true);
stripper.fixedCharWidth = charWidth; // e.g. 5

String text = stripper.getText(document);

fixedCharWidth

它基本上模拟了iText中的类似解决方案 this answer

请注意,这只是概念证明。它特别不考虑任何旋转