In the past two days, the company needs to add a specific picture to the PDF, which is similar to the effect of an electronic seal. I have tried many online methods. After testing, PDF can only insert pictures or achieve exclusive signatures through RSA. I think it is easier to insert pictures. The effect is as follows :
This is the position where "Stamp" last appeared
After zooming in, you can find that the stamp is below the black line. This is because the picture is inserted here. The picture is placed on the bottom layer by layering. The background of the picture must be white, otherwise the background of the picture will also appear, like this :
If your project does not need to consider the possibility of changing the background color of the PDF (most PDF files have a white background color), but simply add a picture at the specified position, then your picture can be arbitrary; if you make an electronic seal like me , and you need to consider the background color, then the background color of your picture must be white. This is a picture I randomly found on Baidu, for reference only:
Tip: If you consider the background color, when the opacity is 100% under non-white, the image will be covered because the color is too heavy; I have been searching for a long time, but I have not yet found a way to modify the transparency of the PDF background color.
If the above effect is consistent with your project's expectations, then start pasting the code below.
1. Depends on:
<dependency>
<groupId>com.itextpdf</groupId>
<artifactId>itextpdf</artifactId>
<version>5.5.13</version>
</dependency>2. Java code:
@Slf4j
public class ImageUtil {
/**
* pdf插入电子印章水印
* @param templatePath 原pdf文件路径
* @param targetPath 生成文件输出路径
* @param imagePath 图片文件路径
* @param keyword 关键字
*/
public static void imageWaterMark(String templatePath,String targetPath,String imagePath,String keyword) {
try {
File pdfFile = new File(templatePath);
byte[] pdfData = new byte[(int) pdfFile.length()];
FileInputStream inputStream = null;
try {
inputStream = new FileInputStream(pdfFile);
inputStream.read(pdfData);
} catch (IOException e) {
log.error("PDF读流异常：" + e);
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
log.error("IO流关闭发生异常：" + e);
}
}
}
//指定关键字
// String keyword = "计算机";
List<float[]> positions = findKeywordPostions(pdfData, keyword);
InputStream input = new FileInputStream(templatePath);
if (positions != null && positions.size() > 0) {
log.info("发现关键字总条数：" + positions.size());
log.info("最后一次出现关键字的位置信息：页码=" + (int)positions.get(positions.size()-1)[0] +
"，X轴=" + positions.get(positions.size()-1)[1] + "，Y轴=" + positions.get(positions.size()-1)[2]);
PdfImage(targetPath,input,imagePath,(int)positions.get(positions.size()-1)[1],
(int)positions.get(positions.size()-1)[2],(int) positions.get(positions.size()-1)[0]);
}else {
log.info("未发现关键字信息");
}
} catch (Exception e) {
log.error("PDF插入图片发生意外异常：" + e);
}
}
/**
* 添加电子签章水印
* @param newPdfPath
* @param srcPdfPath
* @param imagePath
* @param width
* @param height
* @param page
*/
private static void PdfImage(String newPdfPath,InputStream srcPdfPath,String imagePath, int width, int height, int page) {
PdfReader pdfReader = null;
PdfStamper pdfStamper = null;
try {
pdfReader = new PdfReader(srcPdfPath);
//获取最后一页（计算页面插入）
// System.out.println("页数"+pdfReader.getNumberOfPages());
FileOutputStream out = new FileOutputStream(newPdfPath);
pdfStamper = new PdfStamper(pdfReader, out);
//设置最后一页
PdfContentByte pdfContentByte = pdfStamper.getUnderContent(page);
//压缩图片
float qrWidth = 42.75f / 35.4f * 72;
Image qrcodeImage = Image.getInstance(imagePath);
//设置图片宽高
qrcodeImage.scaleToFit(qrWidth, qrWidth);
//水印图片位置坐标
qrcodeImage.setAbsolutePosition(width + 40, height - 45);
//插入图片
pdfContentByte.addImage(qrcodeImage);
pdfStamper.close();
}catch (Exception e) {
log.error("PDF插入图片发生未知异常：" + e);
}finally {
if (pdfReader != null) {
pdfReader.close();
}
}
}
/**
* 查找关键字集合
* @param pdfData
* @param keyword
* @return
* @throws IOException
*/
public static List<float[]> findKeywordPostions(byte[] pdfData, String keyword) {
List<float[]> result = new ArrayList<>();
List<PdfPageContentPositions> pdfPageContentPositions = getPdfContentPostionsList(pdfData);
for (PdfPageContentPositions pdfPageContentPosition : pdfPageContentPositions) {
List<float[]> charPositions = findPositions(keyword, pdfPageContentPosition);
if (charPositions == null || charPositions.size() < 1) {
continue;
}
result.addAll(charPositions);
}
return result;
}
/**
* 读取文件内容
* @param pdfData
* @return
*/
private static List<PdfPageContentPositions> getPdfContentPostionsList(byte[] pdfData) {
try {
PdfReader reader = new PdfReader(pdfData);
List<PdfPageContentPositions> result = new ArrayList<>();
int pages = reader.getNumberOfPages();
for (int pageNum = 1; pageNum <= pages; pageNum++) {
PdfRenderListener pdfRenderListener = new PdfRenderListener(pageNum);
//解析pdf，定位位置
PdfContentStreamProcessor processor = new PdfContentStreamProcessor(pdfRenderListener);
PdfDictionary pageDic = reader.getPageN(pageNum);
PdfDictionary resourcesDic = pageDic.getAsDict(PdfName.RESOURCES);
try {
processor.processContent(ContentByteUtils.getContentBytesForPage(reader, pageNum), resourcesDic);
} catch (Exception e) {
reader.close();
log.error("读取文件内容发生未知异常：" + e);
}
String content = pdfRenderListener.getContent();
List<CharPosition> charPositions = pdfRenderListener.getcharPositions();
List<float[]> positionsList = new ArrayList<>();
for (CharPosition charPosition : charPositions) {
float[] positions = new float[]{charPosition.getPageNum(), charPosition.getX(), charPosition.getY()};
positionsList.add(positions);
}
PdfPageContentPositions pdfPageContentPositions = new PdfPageContentPositions();
pdfPageContentPositions.setContent(content);
pdfPageContentPositions.setPostions(positionsList);
result.add(pdfPageContentPositions);
}
reader.close();
return result;
} catch (Exception e) {
log.error("查找关键字发生未知异常：" + e);
}
}
/**
* 定位关键字位置
* @param keyword
* @param pdfPageContentPositions
* @return
*/
private static List<float[]> findPositions(String keyword, PdfPageContentPositions pdfPageContentPositions) {
List<float[]> result = new ArrayList<>();
String content = pdfPageContentPositions.getContent();
List<float[]> charPositions = pdfPageContentPositions.getPositions();
for (int pos = 0; pos < content.length(); ) {
int positionIndex = content.indexOf(keyword, pos);
if (positionIndex == -1) {
break;
}
float[] postions = charPositions.get(positionIndex);
result.add(postions);
pos = positionIndex + 1;
}
return result;
}
static class CharPosition{
private int pageNum = 0;
private float x = 0;
private float y = 0;
public CharPosition(int pageNum, float x, float y) {
this.pageNum = pageNum;
this.x = x;
this.y = y;
}
public int getPageNum() {
return pageNum;
}
public float getX() {
return x;
}
public float getY() {
return y;
}
@Override
public String toString() {
return "[pageNum=" + this.pageNum + ",x=" + this.x + ",y=" + this.y + "]";
}
}
private static class PdfPageContentPositions {
private String content;
private List<float[]> positions;
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
public List<float[]> getPositions() {
return positions;
}
public void setPostions(List<float[]> positions) {
this.positions = positions;
}
}
private static class PdfRenderListener implements RenderListener {
private int pageNum;
private StringBuilder contentBuilder = new StringBuilder();
private List<CharPosition> charPositions = new ArrayList<>();
public PdfRenderListener(int pageNum) {
this.pageNum = pageNum;
}
public void beginTextBlock() {
}
public void renderText(TextRenderInfo renderInfo) {
List<TextRenderInfo> characterRenderInfos = renderInfo.getCharacterRenderInfos();
for (TextRenderInfo textRenderInfo : characterRenderInfos) {
String word = textRenderInfo.getText();
if (word.length() > 1) {
word = word.substring(word.length() - 1, word.length());
}
Float rectangle = textRenderInfo.getAscentLine().getBoundingRectange();
float x = (float)rectangle.getX();
float y = (float)rectangle.getY();
CharPosition charPosition = new CharPosition(pageNum, (float)x, (float)y);
charPositions.add(charPosition);
contentBuilder.append(word);
}
}
public void endTextBlock() {
}
public void renderImage(ImageRenderInfo renderInfo) {
}
public String getContent() {
return contentBuilder.toString();
}
public List<CharPosition> getcharPositions() {
return charPositions;
}
}
}Paste the above code into your project, download the package and call it, method name: imageWaterMark(); key reminder : If the PDF has been printed using Kingsoft WPS, such PDF cannot recognize text (after opening the PDF, hover the mouse If it turns into a small hand on the PDF, it has been printed).
The above content is the whole content of this sharing, I hope it will be helpful to you who are watching, *★,°*:.☆(￣▽￣)/$:*.°★*.