itext7 获取pdf关键字坐标并进行替换

你的名字 2021-03-26 13:28 1757阅读 2赞

最近项目中有个需求，那就是对pdf文档中的关键字内容进行随意替换，百度跟谷歌上面查了一些资料，已经有大佬给出了该需求的解决方案，目前市面上操作pdf文件使用的比较多的就是`itext`和`pdfbox`，而且解决的方案都是一样的。

说什么itext本身不提供内容替换功能，其实itext7是提供了内容替换功能的，只是我在做的时候遇到了一些问题，就是文档上面没有的字符替换后会以空格的方式展现出来，有兴趣的同学可以去看看。下面这个就是itext7内容替换的例子。

[https://itextpdf.com/en/resources/examples/itext-7/replacing-pdf-objects][https_itextpdf.com_en_resources_examples_itext-7_replacing-pdf-objects]

需要用到背景遮盖，然后再背景上面继续填写要替换的内容，具体解决方案分为下面这几步

*  找到关键字的坐标位置
 *  将关键字坐标设置白色的背景，因为pdf的背景都是白色的
 *  将需要替换的关键字填充到白色背景上面

通过上面这几步我们就达到了所谓的替换功能。下面给个效果图

##### 源文件 #####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MDgyMzA0_size_16_color_FFFFFF_t_70]

#### 替换后的文件 ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MDgyMzA0_size_16_color_FFFFFF_t_70 1]

### 核心代码 ###

public class ReplaceUtils { 
    
        public static void doOverText(OverTextDTO overTextDTO) throws IOException { 
    
            Map<String,String> keyMap = new HashMap<String, String>();
    
            //为key自动加上占位符并转义
            for(String key : overTextDTO.getReplaceMap().keySet()) { 
                keyMap.put(key,"\\$\\{" + key + "\\}");
            }
            List<List<OverAreaDTO>> lists =
                    getTextPosition(overTextDTO.getSourceFilePath(),overTextDTO.getFinishFilePath(),keyMap,overTextDTO.getReplaceMap());
    
            overText(overTextDTO.getSourceFilePath(),overTextDTO.getFinishFilePath(),lists,overTextDTO.getFont());
        }
    
        /** * 获取关键字的坐标 * @param keyMap * @return */
        public static  List<List<OverAreaDTO>> getTextPosition(String sourcePath,String finishPath, Map<String,String> keyMap,Map<String,String> replaceMap) throws IOException { 
    
            PdfReader reader = new PdfReader(sourcePath);
            PdfDocument pdfDocument = new PdfDocument(reader, new PdfWriter(finishPath));
    
            List<List<OverAreaDTO>> list = new ArrayList<List<OverAreaDTO>>();
    
            for (int i = 1; i <= pdfDocument.getNumberOfPages(); i++) { 
    
    
                List<OverAreaDTO> overAreaDTOS = new ArrayList<OverAreaDTO>();
    
                for (String key  : keyMap.keySet()) { 
    
                    PdfPage page = pdfDocument.getPage(i);
    
                    RegexBasedLocationExtractionStrategy strategy = new RegexBasedLocationExtractionStrategy(keyMap.get(key));
                    PdfCanvasProcessor canvasProcessor = new PdfCanvasProcessor(strategy);
                    canvasProcessor.processPageContent(page);
                    Collection<IPdfTextLocation> resultantLocations = strategy.getResultantLocations();
                    PdfCanvas pdfCanvas = new PdfCanvas(page);
                    pdfCanvas.setLineWidth(0.5f);
    
                    for (IPdfTextLocation location : resultantLocations) { 
                        Rectangle rectangle = location.getRectangle();
                        pdfCanvas.rectangle(rectangle);
                        pdfCanvas.setStrokeColor(ColorConstants.RED);
                        pdfCanvas.stroke();
    
                        OverAreaDTO overAreaDTO = new OverAreaDTO();
                        overAreaDTO.setPageNum(location.getPageNumber());
                        overAreaDTO.setX(rectangle.getX());
                        overAreaDTO.setY(rectangle.getY());
                        overAreaDTO.setWidth(rectangle.getWidth());
                        overAreaDTO.setHeight(rectangle.getHeight());
                        overAreaDTO.setKey(key);
                        overAreaDTO.setValue(replaceMap.get(key));
                        overAreaDTOS.add(overAreaDTO);
                    }
                }
    
                list.add(overAreaDTOS);
            }
            pdfDocument.close();
    
            return list;
        }
    
        /** * 覆盖原有的内容 并填充新内容 * * @param sourcePath 源文件 * @param finishPath 替换后的文件 * @param list */
        public static void overText(String sourcePath,String finishPath,List<List<OverAreaDTO>> list,PdfFont font) throws IOException { 
            PdfDocument pdfDoc = new PdfDocument(new PdfReader(sourcePath), new PdfWriter(finishPath));
            //pdfDoc.getFirstPage().newContentStreamAfter() 会覆盖掉字体
            //pdfDoc.getFirstPage().newContentStreamBefore() 只会在字体的下层添加一个背景色
            for (int i = 1; i <= pdfDoc.getNumberOfPages(); i++) { 
                PdfCanvas canvas = new PdfCanvas(pdfDoc.getPage(i).newContentStreamAfter(),
                        pdfDoc.getPage(i).getResources(), pdfDoc);
    
                canvas.saveState();
                List<OverAreaDTO> overAreaDTOS = list.get(i-1);
                //用白色背景覆盖原本的字体
                for (OverAreaDTO overArea :overAreaDTOS) { 
                    canvas.setFillColor(ColorConstants.WHITE);
                    //覆盖的时候y + 0.35 填充字体的时候 + 1.5 主要就是避免覆盖占位符下面的线
                    canvas.rectangle(overArea.getX(), overArea.getY() + 0.35, overArea.getWidth(), overArea.getHeight());
                }
                canvas.fill();
                canvas.restoreState();
    
                //填充新内容
                canvas.beginText();
                for (OverAreaDTO overArea :overAreaDTOS) { 
                    canvas.setFontAndSize(font,overArea.getHeight());
                    canvas.setTextMatrix(overArea.getX(),overArea.getY() + 1.5f);
                    canvas.newlineShowText(overArea.getValue());
                }
                canvas.endText();
            }
    
            pdfDoc.close();
    
        }
    }

[项目源码:https://github.com/niezhiliang/itext-pdf-replace][https_github.com_niezhiliang_itext-pdf-replace]

[https_itextpdf.com_en_resources_examples_itext-7_replacing-pdf-objects]: https://itextpdf.com/en/resources/examples/itext-7/replacing-pdf-objects
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MDgyMzA0_size_16_color_FFFFFF_t_70]: /images/20210326/1616765293228.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4MDgyMzA0_size_16_color_FFFFFF_t_70 1]: /images/20210326/1616765272249.png
[https_github.com_niezhiliang_itext-pdf-replace]: https://github.com/niezhiliang/itext-pdf-replace