itext实现合同尾部签章部分自动添加，定位签名

使用的pom

<!-- pdf处理 start-->

<dependency>

    <groupId>com.itextpdf</groupId>

    <artifactId>itext-asian</artifactId>

    <version>5.2.0</version>

</dependency>

<dependency>

    <groupId>com.itextpdf</groupId>

    <artifactId>itextpdf</artifactId>

    <version>5.5.4</version>

</dependency>

<!-- https://mvnrepository.com/artifact/com.itextpdf/kernel -->

<dependency>

    <groupId>com.itextpdf</groupId>

    <artifactId>kernel</artifactId>

    <version>7.1.2</version>

</dependency>

<!-- https://mvnrepository.com/artifact/com.itextpdf/layout -->

<dependency>

    <groupId>com.itextpdf</groupId>

    <artifactId>layout</artifactId>

    <version>7.1.2</version>

</dependency>

<dependency>

    <groupId>org.bouncycastle</groupId>

    <artifactId>bcprov-jdk15on</artifactId>

    <version>1.49</version>

</dependency>

<!-- https://mvnrepository.com/artifact/com.itextpdf/forms -->

<dependency>

    <groupId>com.itextpdf</groupId>

    <artifactId>forms</artifactId>

    <version>7.1.4</version>

</dependency>

<dependency>

    <groupId>org.bouncycastle</groupId>

    <artifactId>bcpkix-jdk15on</artifactId>

    <version>1.49</version>

</dependency>

<!-- pdf处理 end-->

效果图

原理

1. 通过itext中List添加固定文本
2. 添加指定标记比如★☆用以之后替换成其他文本或图片
3. 可以不用标记，反正就是算好位置
4. 至于签章这块位置的选定，根据文档最后一行位置判定，我的判定方法就是文档最后一页最后一行离尾部距离小于一定值，签章的整块内容移到新的一页

过程

1. 核心利用了com.itextpdf.text.pdf.parser.RenderListener这个类，它会遍历这个文档的内容
2. 写个继承这个类的方法，实现方法如下

@Override

public void renderText(TextRenderInfo textInfo) {

    Float bound = textInfo.getBaseline().getBoundingRectange();

    String text = textInfo.getText();

    float y = bound.y - this.fixHeight;

    for (String keyWord : findText) {

        if (null != text && text.contains(keyWord)) {

            ReplaceRegion region = new ReplaceRegion(keyWord);

            region.setH(bound.height == 0 ? defaultH : bound.height);

            if ((text.contains("☆") && keyWord.equals("☆"))) {

                region.setW(20f);

                int i = text.indexOf("☆");

                region.setX(bound.x + 13 * i);

            } else if (text.contains("★") && keyWord.equals("★")) {

                region.setW(15f);

                region.setX(bound.x);

            } else if ((text.contains("△") && keyWord.equals("△"))) {

                region.setW(15f);

                int i = text.indexOf("△");

                region.setX(bound.x + 11 * i);

            } else if ((text.contains("▲") && keyWord.equals("▲"))) {

                region.setW(15f);

                region.setX(bound.width + 15 * 4.5f);

            } else {

                region.setW(bound.width);

                region.setX(bound.x);

            }

            region.setY(y);

            result.put(keyWord, region);

        }

    }

    //判断最后一行是否小于某个值

    if (y < heightSign) {

        signY.put("endY", 0f);

    } else {

        signY.put("endY", y);

    }

}

1. 这里我进行了很多微调，此方法肯定存在很多改进的地方，由于时间紧急，我对itext的研究也不深，勉强实现需求

...

PdfReader reader = new PdfReader(pdfBytes);

//内容解析器

PdfReaderContentParser parser = new PdfReaderContentParser(reader);

for (int i = 1; i <= numberOfPages; i++) {

    parser.processContent(i, listener);

    Map<String, ReplaceRegion> res = listener.getResult(i);

    if (res.size() > 0) {

        pdfReplacer.setPageNum(i);

        result = res;

    }

}

...

1. 通过上面的步骤找到最后一行位置，找到指定特殊字符的位置
2. 添加尾部签章部分通过

PdfReader reader = new PdfReader(basePath + "_temp2.pdf");

PdfWriter writer = new PdfWriter(basePath + "_temp3.pdf");

PdfDocument pdf = new PdfDocument(reader, writer);

int numberOfPages = pdf.getNumberOfPages();

float height = pdf.getDefaultPageSize().getHeight();

if (endY == 0f) {

    numberOfPages++;

    endY = height - 140f;

    pdf.addNewPage();

}else{

    endY = endY - 60f;

}

Document doc = new Document(pdf);

PdfFont font = PdfFontFactory.createFont("C:/Windows/Fonts/simsun.ttc,1", PdfEncodings.IDENTITY_H,true);

com.itextpdf.layout.element.List list = new com.itextpdf.layout.element.List().setPageNumber(numberOfPages).setFixedPosition(80,endY,400f).setListSymbol("").setSymbolIndent(22f).setFont(font).setFontSize(14);

list.add(new ListItem("甲方法定代表人：☆            乙方法定代表人： △"))

    .add(new ListItem("联系电话：                    联系电话："))

    .add(new ListItem("身份证号码：                  身份证号码："))

    .add(new ListItem("★                            ▲"));

doc.add(list);

pdf.close();

1. 整个过程会出现很多中间临时文件，所以说还是可以有很多改进的地方。

2. 替换方法，用来替换日期，和覆盖特殊符号

textReplacer = new PdfReplacer(basePath + "_temp3.pdf");

textReplacer.replaceText(replaceStr, destStr.toString());

replaceRegion = textReplacer.toPdf(basePath + "_temp4.pdf");

PdfReplacer textReplacer2 = new PdfReplacer(basePath + "_temp4.pdf");

String dateRecord = sysconfig.getProperties().getProperty(dateSign);

String text = DateUtil.format2str("yyyy 年  MM 月  dd 日");

textReplacer2.setFont(14);

String dateFontPath = sysconfig.getProperties().getProperty("date_font_path");

if (dateFontPath.lastIndexOf("ttf") > 0) {

    textReplacer2.setFont(new com.itextpdf.text.Font(BaseFont.createFont(dateFontPath, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED)));

} else {

    dateFontPath = dateFontPath + ",1";

    textReplacer2.setFont(new com.itextpdf.text.Font(BaseFont.createFont(dateFontPath, BaseFont.IDENTITY_H, BaseFont.NOT_EMBEDDED)));

}

log.info("字体路径{}", dateFontPath);

textReplacer2.replaceText(dateRecord, text);

1. 签章方法

public static byte[] sign(String password, InputStream inputStream, String signPdfSrc, String signImage,

                          float x, float y,int page) {

    File signPdfSrcFile = new File(signPdfSrc);

    PdfReader reader = null;

    ByteArrayOutputStream signPDFData = null;

    PdfStamper stp = null;

    try {

        BouncyCastleProvider provider = new BouncyCastleProvider();

        Security.addProvider(provider);

        KeyStore ks = KeyStore.getInstance("PKCS12", new BouncyCastleProvider());

        // 私钥密码 为Pkcs生成证书是的私钥密码 123456

        ks.load(inputStream, password.toCharArray());

        String alias = (String) ks.aliases().nextElement();

        PrivateKey key = (PrivateKey) ks.getKey(alias, password.toCharArray());

        Certificate[] chain = ks.getCertificateChain(alias);

        reader = new PdfReader(signPdfSrc);

        signPDFData = new ByteArrayOutputStream();

        // 临时pdf文件

        File temp = new File(signPdfSrcFile.getParent(), System.currentTimeMillis() + ".pdf");

        stp = PdfStamper.createSignature(reader, signPDFData, '\0', temp, true);

        stp.setFullCompression();

        PdfSignatureAppearance sap = stp.getSignatureAppearance();

        sap.setReason("数字签名，不可改变");

        // 使用png格式透明图片

        Image image = Image.getInstance(signImage);

        sap.setImageScale(0);

        sap.setSignatureGraphic(image);

        sap.setRenderingMode(RenderingMode.GRAPHIC);

        int size = 120;

        // 是对应x轴和y轴坐标

        float lly = y - 50;

        sap.setVisibleSignature(new Rectangle(x, lly, x + size, lly+size), page,

                UUID.randomUUID().toString().replaceAll("-", ""));

        stp.getWriter().setCompressionLevel(5);

        ExternalDigest digest = new BouncyCastleDigest();

        ExternalSignature signature = new PrivateKeySignature(key, DigestAlgorithms.SHA512, provider.getName());

        MakeSignature.signDetached(sap, digest, signature, chain, null, null, null, 0, CryptoStandard.CADES);

        stp.close();

        reader.close();

        return signPDFData.toByteArray();

    } catch (Exception e) {

        e.printStackTrace();

    } finally {

        if (signPDFData != null) {

            try {

                signPDFData.close();

            } catch (IOException e) {

            }

        }

        if (inputStream != null) {

            try {

                inputStream.close();

            } catch (IOException e) {

            }

        }

    }

    return null;

}