itext7知识点研究（PDF编辑）

取出pdf文档文字

String sourceFolder2 = "E:\\picture2\\租赁合同2.pdf";
PdfDocument doc = new PdfDocument(new PdfReader(sourceFolder2));
float height = doc.getPage(1).getPageSize().getHeight();
float width = doc.getPage(1).getPageSize().getWidth();
Rectangle rect = new Rectangle(width,height);
FilteredTextEventListener filterListener = new FilteredTextEventListener(new LocationTextExtractionStrategy(), new TextRegionEventFilter(rect));
String extractedText = PdfTextExtractor.getTextFromPage(doc.getPage(1), filterListener);
System.out.println(extractedText);

• 上面的例子就可以取出第一页所有的文字，如果需要取出某些文字需要知道文字的具体方位，画个矩形就可以取出
• 以上代码依赖com.itextpdf.kernel

2. 取出多个位置的文字

@Test
public void testWithMultiFilteredRenderListener() throws IOException {
    PdfDocument pdfDocument = new PdfDocument(new PdfReader(sourceFolder + "test.pdf"));

    float x1, y1, x2, y2;

    FilteredEventListener listener = new FilteredEventListener();
    x1 = 122;
    x2 = 22;
    y1 = 678.9f;
    y2 = 12;
    ITextExtractionStrategy region1Listener = listener.attachEventListener(new LocationTextExtractionStrategy(),
            new TextRegionEventFilter(new Rectangle(x1, y1, x2, y2)));

    x1 = 156;
    x2 = 13;
    y1 = 678.9f;
    y2 = 12;
    ITextExtractionStrategy region2Listener = listener.attachEventListener(new LocationTextExtractionStrategy(),
            new TextRegionEventFilter(new Rectangle(x1, y1, x2, y2)));

    PdfCanvasProcessor parser = new PdfCanvasProcessor(new GlyphEventListener(listener));
    parser.processPageContent(pdfDocument.getPage(1));

    Assert.assertEquals("Your", region1Listener.getResultantText());
    Assert.assertEquals("dju", region2Listener.getResultantText());
}

3. 遍历pdf每个字符

   • 之前一直以为Listen监听遍历pdf文本只能一段一段遍历，现在发现他实际上提供了遍历字符的方法\
   • 两个监听器，一个监听的段落，一个监听每个字符

   static class MyEventListener implements IEventListener {
       private List<Rectangle> rectangles = new ArrayList<>();
   
       @Override
       public void eventOccurred(IEventData data, EventType type) {
           if (type == EventType.RENDER_TEXT) {
               TextRenderInfo renderInfo = (TextRenderInfo) data;
               Vector startPoint = renderInfo.getDescentLine().getStartPoint();
               Vector endPoint = renderInfo.getAscentLine().getEndPoint();
               float x1 = Math.min(startPoint.get(0), endPoint.get(0));
               float x2 = Math.max(startPoint.get(0), endPoint.get(0));
               float y1 = Math.min(startPoint.get(1), endPoint.get(1));
               float y2 = Math.max(startPoint.get(1), endPoint.get(1));
               rectangles.add(new Rectangle(x1, y1, x2 - x1, y2 - y1));
           }
       }
   
       @Override
       public Set<EventType> getSupportedEvents() {
           return new LinkedHashSet<>(Collections.singletonList(EventType.RENDER_TEXT));
       }
   
       public List<Rectangle> getRectangles() {
           return rectangles;
       }
   
       public void clear() {
           rectangles.clear();
       }
   }
   
   static class MyCharacterEventListener extends MyEventListener {
       @Override
       public void eventOccurred(IEventData data, EventType type) {
           if (type == EventType.RENDER_TEXT) {
               TextRenderInfo renderInfo = (TextRenderInfo) data;
               for (TextRenderInfo tri : renderInfo.getCharacterRenderInfos()) {
                   super.eventOccurred(tri, type);
               }
           }
       }
   }
   

   • 标记每个字符，提供了这样的方法，可以发挥想象做更多的事，给个图片更清楚点

   private void parseAndHighlight(String input, String output, boolean singleCharacters) throws IOException {
       PdfDocument pdfDocument = new PdfDocument(new PdfReader(input), new PdfWriter(output));
   
       MyEventListener myEventListener = singleCharacters ? new MyCharacterEventListener() : new MyEventListener();
       PdfDocumentContentParser parser = new PdfDocumentContentParser(pdfDocument);
       for (int pageNum = 1; pageNum <= pdfDocument.getNumberOfPages(); pageNum++) {
           parser.processContent(pageNum, myEventListener);
           List<Rectangle> rectangles = myEventListener.getRectangles();
           PdfCanvas canvas = new PdfCanvas(pdfDocument.getPage(pageNum));
           canvas.setLineWidth(0.5f);
           canvas.setStrokeColor(ColorConstants.RED);
           for (Rectangle rectangle : rectangles) {
               canvas.rectangle(rectangle);
               canvas.stroke();
           }
           myEventListener.clear();
       }
   
       pdfDocument.close();
   }
   

   

   • 要实现上面的效果，只要调用上面的方法即可

   @Test
   public void highlightNotDefTest() throws IOException, InterruptedException {
       String input = sourceFolder + "page229.pdf";
       String output = outputPath + "page229.pdf";
       //false 表示短语单词为单位 true表示每个字符都遍历
       parseAndHighlight(input, output, false);
   }
   

   • false的效果
     

4. 定位某些单词

@Test
public void findPosition() throws Exception {
    String sourceFolder2 = "E:\\picture2\\租赁合同2.pdf";
    String output = "E:\\picture2\\租赁合同2_stroke.pdf";
    PdfReader reader = new PdfReader(sourceFolder2);
    PdfDocument pdfDocument = new PdfDocument(reader, new PdfWriter(output));
    PdfPage lastPage = pdfDocument.getLastPage();
    RegexBasedLocationExtractionStrategy strategy = new RegexBasedLocationExtractionStrategy("甲方");
    PdfCanvasProcessor canvasProcessor = new PdfCanvasProcessor(strategy);
    canvasProcessor.processPageContent(lastPage);
    Collection<IPdfTextLocation> resultantLocations = strategy.getResultantLocations();
    PdfCanvas pdfCanvas = new PdfCanvas(lastPage);
    pdfCanvas.setLineWidth(0.5f);
    List<IPdfTextLocation> sets = new ArrayList<>();
    for (IPdfTextLocation location : resultantLocations) {
        Rectangle rectangle = location.getRectangle();
        pdfCanvas.rectangle(rectangle);
        pdfCanvas.setStrokeColor(ColorConstants.RED);
        pdfCanvas.stroke();
        System.out.println(rectangle.getX() + "," + rectangle.getY() + "," + rectangle.getLeft() + "," +
                rectangle.getRight() + "," + rectangle.getTop() + "," + rectangle.getBottom() + "," +
                rectangle.getWidth() + "," + rectangle.getHeight());
        System.out.println(location.getText());
        sets.add(location);
    }
    Collections.sort(sets, new Comparator<IPdfTextLocation>() {
        @Override
        public int compare(IPdfTextLocation o1, IPdfTextLocation o2) {
            return o1.getRectangle().getY() - o2.getRectangle().getY() > 0 ? 1 : o1.getRectangle().getY() - o2.getRectangle().getY() == 0 ? 0 : -1;
        }
    });
    System.out.println(sets.get(0).getRectangle().getY());
    pdfDocument.close();
}

• 以下是输出

88.0,297.53,88.0,115.72,311.53,297.53,27.720001,14.0
甲方
213.0,674.176,213.0,241.0,688.176,674.176,28.0,14.0
甲方
227.75,767.7765,227.75,254.75,781.2765,767.7765,27.0,13.5
甲方
322.25,767.7765,322.25,349.25,781.2765,767.7765,27.0,13.5
甲方
297.53

• 上面的方法用来合同签章定位上，已经可以做到定位最后某个特定单词

添加文字和图片

@Test
public void imagesWithDifferentDepth() throws IOException, InterruptedException {
    String outFileName = destinationFolder + "transparencyTest01.pdf";
    String cmpFileName = sourceFolder + "cmp_transparencyTest01.pdf";
    PdfDocument pdfDocument = new PdfDocument(new PdfWriter(outFileName, new WriterProperties()
            .setCompressionLevel(CompressionConstants.NO_COMPRESSION)));
    PdfPage page = pdfDocument.addNewPage(PageSize.A3);//默认添加A4
    PdfCanvas canvas = new PdfCanvas(page);
    canvas.setFillColor(ColorConstants.LIGHT_GRAY).fill();//设置填充背景色
    canvas.rectangle(80, 0, 700, 1200).fill();
    //开始添加文字
    canvas
            .saveState()
            .beginText()
            .moveText(116, 1150) //从哪里开始写
            .setFontAndSize(PdfFontFactory.createFont(StandardFonts.HELVETICA), 14) //字体和大小
            .setFillColor(ColorConstants.MAGENTA) //字体颜色
            .showText("8 bit depth PNG") //具体展示的文字
            .endText()
            .restoreState();
    //读取并添加图片到指定位置
    ImageData img = ImageDataFactory.create(sourceFolder + "manualTransparency_8bit.png");
    canvas.addImage(img, 100, 780, 200, false);
    
    //收尾步骤，关闭画布和pdf，否则pdf打开错误
    canvas.release();
    pdfDocument.close();

}

覆盖原来的文字

1. 由于itext没提供替换pdf文字的接口，只能通过覆盖文字的形式完成

public void manipulatePdf(String src, String dest) throws IOException, DocumentException {
        PdfReader reader = new PdfReader(src);
        PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
        PdfContentByte canvas = stamper.getUnderContent(1);
        canvas.saveState();
        canvas.setColorFill(BaseColor.YELLOW);
        canvas.rectangle(36, 786, 66, 16);
        canvas.fill();
        canvas.restoreState();
        
        //开始写入文本 
        canvas.beginText(); 
        for (Entry<String, ReplaceRegion> entry : entrys) {
        	ReplaceRegion val = entry.getValue();
        	//设置字体
        	canvas.setFontAndSize(font.getBaseFont(), getFontSize());  
            canvas.setTextMatrix(val.getX(),val.getY()+2/*修正背景与文本的相对位置*/);
            canvas.showText((String) replaceTextMap.get(value.getAliasName()));
		}
        canvas.endText();
        
        stamper.close();
        reader.close();
    }