itext实现pdf自动定位合同签订

需求

  1. 需要实现如下效果(最终效果)

思考

  1. 需求方的要求就是实现签订合同,实现方法不限,但过程中又提出需要在签章的过程中把签订日期的文字也打上去,这就有点坑了~
  2. 一开始的想法是想办法定位需要签名的位置,事实上同类app实现方式就是这样,在前端实现签名位置定位,把位置信息发给后端,后端就可以很方便把印章放上去。
  3. 但现实是现在前端不靠谱,暂时不能提供这样的功能;而且日期信息的填写也需要定位,这怎么办?用户不会手动去定位日期的位置,最多会调整下签名的位置才合理
  4. 然后我研究了下itext的api,并讨论决定尾部签名部分我们自己做。也就是上图中的下半部分的所有内容,包括甲方乙方,日期,签章等都通过程序自动定位上去
  5. 这样的想法遇到的难点,首先是y轴的定位问题。首先要找到文档的尾行在哪,在适当的距离进行文字的填写。我没有找到可以直接在文档末尾添加文字的api,如果各位知道麻烦指教一下

步骤

  1. 因为有上述的问题,我首先考虑要找到尾行的文字才会考虑写代码。通过api研究,可以通过itext的监听器遍历文本拿到尾行文字等信息
  2. x周位置根据页面宽度调整
  3. 文字大小和字体类型问题。字体类型是我现在也没解决的,我没找到获取pdf文档字体类型和大小的api,请指教
  4. 因为没找到api所以我用的最笨的方法,通过获取字体的高度来确定字体大小,这样的文字写出来差别不会太大。至于字体,只能认为规定,合同字体统一宋体。
  5. 过程中还遇到的问题就是字体左边距对齐问题,很明显甲乙方在一行上,中间用空格来分割的话会很不标准。所以我最终决定用table,且左右边签名和文字分开进行写入。也就是甲签的时候写左半部分,乙签的时候写右半部分。当签完后就是上图的效果
  6. 说了这么多接下来直接上工具代码吧,如果要使用,直接把几个类代码复制过去,把字体路径换成自己的,文件路径改下就可以在main方法运行测试了

上代码

  1. PdfParser类,主要实现类,包含了main方法
package com.zhiyis.framework.util.itext;

import com.itextpdf.io.font.PdfEncodings;
import com.itextpdf.kernel.font.PdfFont;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.geom.Rectangle;
import com.itextpdf.kernel.geom.Vector;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.parser.EventType;
import com.itextpdf.kernel.pdf.canvas.parser.PdfDocumentContentParser;
import com.itextpdf.kernel.pdf.canvas.parser.data.IEventData;
import com.itextpdf.kernel.pdf.canvas.parser.data.TextRenderInfo;
import com.itextpdf.kernel.pdf.canvas.parser.listener.IEventListener;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.borders.Border;
import com.itextpdf.layout.element.Cell;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.element.Table;
import com.zhiyis.common.utils.DateUtil;
import com.zhiyis.common.utils.Sysconfig;
import com.zhiyis.framework.util.FileUtil;
import com.zhiyis.framework.util.SignPdf;
import lombok.extern.slf4j.Slf4j;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;


/**
 * @author laoliangliang
 * @date 2018/11/23 15:03
 */
@Slf4j
public class PdfParser {

    private Sysconfig sysconfig;

    public PdfParser() {
    }

    public PdfParser(Sysconfig sysconfig) {
        this.sysconfig = sysconfig;
    }

    public enum SignType {
        //甲签
        SIGN_A(1),
        //乙签
        SIGN_B(2);
        private Integer type;

        SignType(Integer type) {
            this.type = type;
        }

        public Integer getType() {
            return type;
        }
    }

    public static void main(String[] args) {
        List<String> contents = new ArrayList<>();
        contents.add("甲方法定代表人:");
        contents.add("联系电话:");
        contents.add("身份证号码:");
        contents.add(DateUtil.format2str("yyyy 年  MM 月  dd 日"));
        String input = "/Users/laoliangliang/Downloads/合同模板 (1).pdf";
        String tempPath = "/Users/laoliangliang/Downloads/合同模板_signed.pdf";

        String filePath = "/Users/laoliangliang/Downloads/31.png";
        String fileOut = "/Users/laoliangliang/Downloads/合同模板_signed_signed_signed.pdf";
        PdfParser pdfParser = new PdfParser();
//        pdfParser.startSign(input, input, fileOut, filePath, SignType.SIGN_A, contents, false);
        pdfParser.startSign(input, fileOut, tempPath, filePath, SignType.SIGN_B, contents, true);
    }

    /**
     * 甲乙方签名方法
     *
     * @param rootPath 初始合同pdf路径
     * @param tempPath 基于哪份合同签章,比如甲方先签,这里填的就是初始合同地址;若是乙方签,这里填的就是甲方签过生成的合同地址
     * @param outPath  输出的合同地址,包含文件名
     * @param imgPath  签章图片地址
     * @param signType 甲方签章还是乙方签章,输入枚举类型
     * @param contents 签章处文本内容
     * @param already  理论上甲签的时候是false,表示没有签过,乙签的时候是true,表示甲已经签过,就算下面高度不够也不会新增页面
     *                 若需求改动,可以乙先签,那逻辑控制,先签的false,后签的true;
     *                 该项错误可能导致第二方签章时新启一页签章
     */
    public void startSign(String rootPath, String tempPath, String outPath, String imgPath, SignType signType, List<String> contents, boolean already) {
        String tempRootPath = "";
        try {
            //读取文章尾部位置
            MyRectangle myRectangle = getLastWordRectangle(rootPath);
            //还没签印的,临时文件路径
            tempRootPath = rootPath.substring(0, rootPath.length() - 4) + "_temp.pdf";
            //添加尾部内容
            SignPosition signPosition = addTailSign(myRectangle, tempPath, tempRootPath, signType.getType(), contents, already);
            InputStream in = PdfParser.class.getClassLoader().getResourceAsStream("keystore.p12");
            byte[] fileData = SignPdf.sign("123456", in, tempRootPath, imgPath, signPosition.getX(), signPosition.getY(), signPosition.getPageNum());
            FileUtil.uploadFile(fileData, outPath);
        } catch (Exception e) {
            log.error("签名出错", e);
        } finally {
            File file = new File(tempRootPath);
            if (file.exists()) {
                boolean flag = file.delete();
                if (flag) {
                    log.debug("临时文件删除成功");
                }
            }
        }
    }

    /**
     * 添加尾部签名部分(不含签名或印章)
     *
     * @param myRectangle 文档末尾位置和大致信息
     * @param input       输入文档路径
     * @param output      输出文档路径
     * @param type        1-甲签 2-乙签
     * @param content     填写内容
     * @param already     理论上甲签的时候是false,表示没有签过,乙签的时候是true,表示甲已经签过,就算下面高度不够也不会新增页面
     *                    若需求改动,可以乙先签,那逻辑控制,先签的false,后签的true
     * @throws Exception
     */
    private SignPosition addTailSign(MyRectangle myRectangle, String input, String output, Integer type, List<String> content, boolean already) throws Exception {

        PdfReader reader = new PdfReader(input);
        PdfWriter writer = new PdfWriter(output);
        PdfDocument pdf = new PdfDocument(reader, writer);
        int numberOfPages = pdf.getNumberOfPages();

        Document doc = new Document(pdf);
        String dateFontPath;
        if (sysconfig == null) {
            dateFontPath = "/Library/Fonts/simsun.ttc";
        }else{
            dateFontPath = sysconfig.getProperties().getProperty("date_font_path");
        }
        PdfFont font = PdfFontFactory.createFont(dateFontPath + ",1", PdfEncodings.IDENTITY_H, true);
        //判断签名高度是否够
        int size = content.size();
        float maxRecHeight = myRectangle.getMinlineHeight() * size;
        float v = myRectangle.getBottom() - maxRecHeight;
        boolean isNewPage = false;
        if (v <= myRectangle.getMinlineHeight() * 3) {
            isNewPage = true;
            if (!already) {
                pdf.addNewPage();
                numberOfPages++;
            }
            myRectangle.setBottom(myRectangle.getTop() * 2 - maxRecHeight * 2);
        }
        Table table = new Table(1);
        table.setPageNumber(numberOfPages);
        float bottom = (myRectangle.getBottom() - maxRecHeight) / 2;
        float left1;
        left1 = myRectangle.getLeft() + 30f;
        if (type == 2) {
            left1 = left1 + myRectangle.getWidth() / 2 - 15;
        }
        myRectangle.setLeft(left1);
        table.setFixedPosition(left1, bottom, 200);
        table.setBorder(Border.NO_BORDER);


        for (String text : content) {
            Paragraph paragraph = new Paragraph();
            paragraph.add(text).setFont(font).setFontSize(myRectangle.getHeight());
            Cell cell = new Cell();
            cell.add(paragraph);
            cell.setBorder(Border.NO_BORDER);
            table.addCell(cell);
        }

        doc.add(table);
        doc.flush();
        pdf.close();
        return getSignPosition(myRectangle, content, bottom, numberOfPages, isNewPage);
    }

    private SignPosition getSignPosition(MyRectangle myRectangle, List<String> content, float bottom, int numberOfPages, boolean isNewPage) {
        SignPosition signPosition = new SignPosition();
        //y轴位置,底部
        if (isNewPage) {
            signPosition.setY(bottom + (content.size() - 2) * myRectangle.getMinlineHeight());
        } else {
            signPosition.setY(bottom + (content.size() - 3) * myRectangle.getMinlineHeight());
        }
        //x轴位置,文字宽度+偏移量
        signPosition.setX(myRectangle.getLeft() + content.get(0).length() * myRectangle.getHeight() - 15f);
        signPosition.setPageNum(numberOfPages);
        return signPosition;
    }

    /**
     * 拿到文章末尾参数
     */
    private MyRectangle getLastWordRectangle(String input) throws IOException {
        PdfDocument pdfDocument = new PdfDocument(new PdfReader(input));
        MyEventListener myEventListener = new MyEventListener();
        PdfDocumentContentParser parser = new PdfDocumentContentParser(pdfDocument);
        parser.processContent(pdfDocument.getNumberOfPages(), myEventListener);
        List<Rectangle> rectangles = myEventListener.getRectangles();
        float left = 100000;
        float right = 0;
        float bottom = 100000;
        boolean isTop = true;
        Rectangle tempRec = null;
        float minV = 1000;
        MyRectangle myRectangle = new MyRectangle();
        //拿到文本最左最下和最右位置
        for (Rectangle rectangle : rectangles) {
            if (isTop) {
                myRectangle.setTop(rectangle.getY());
                isTop = false;
            }
            if (tempRec != null) {
                float v = tempRec.getY() - rectangle.getY();
                if (v < minV && v > 5f) {
                    minV = v;
                }
            }
            tempRec = rectangle;
            float lt = rectangle.getLeft();
            float rt = rectangle.getRight();
            float y = rectangle.getBottom();
            if (lt < left) {
                left = lt;
            }
            if (rt > right) {
                right = rt;
            }
            if (y < bottom) {
                bottom = y;
            }

        }
        Rectangle rectangle = rectangles.get(rectangles.size() - 1);
        float height = rectangle.getHeight();
        myRectangle.setHeight(height);
        myRectangle.setLeft(left);
        myRectangle.setRight(right);
        myRectangle.setBottom(bottom);
        myRectangle.setMinlineHeight(minV);
        myRectangle.setLineSpace(minV - height);
        myRectangle.setWidth(right - left);
        pdfDocument.close();
        return myRectangle;
    }


    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;
                if ("".equals(renderInfo.getText().trim())) {
                    return;
                }
                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();
        }
    }

}
  1. MyRectangle 用来存文档尾部数据的实体类
package com.zhiyis.framework.util.itext;

/**
 * @author laoliangliang
 * @date 2018/11/23 16:11
 */
public class MyRectangle {

    private float width;
    private float left;
    private float right;
    private float bottom;
    private float top;
    private float height;
    /**
     * 行间间隔
     */
    private float lineSpace;
    /**
     * 最小行间距,从上一行底部到下一行底部的距离
     */
    private float minlineHeight;
    public float getWidth() {
        return width;
    }

    public void setWidth(float width) {
        this.width = width;
    }
    public float getLeft() {
        return left;
    }

    public void setLeft(float left) {
        this.left = left;
    }

    public float getRight() {
        return right;
    }

    public void setRight(float right) {
        this.right = right;
    }

    public float getBottom() {
        return bottom;
    }

    public void setBottom(float bottom) {
        this.bottom = bottom;
    }

    public float getHeight() {
        return height;
    }

    public void setHeight(float height) {
        this.height = height;
    }

    public float getLineSpace() {
        return lineSpace;
    }

    public void setLineSpace(float lineSpace) {
        this.lineSpace = lineSpace;
    }

    public float getMinlineHeight() {
        return minlineHeight;
    }

    public void setMinlineHeight(float minlineHeight) {
        this.minlineHeight = minlineHeight;
    }

    public float getTop() {
        return top;
    }

    public void setTop(float top) {
        this.top = top;
    }
}
  1. SignPosition 签章位置类
package com.zhiyis.framework.util.itext;

/**
 * 签章位置类
 * @author laoliangliang
 * @date 18/11/24 下午1:43
 */
public class SignPosition {

    private float x;

    private float y;

    private float width;

    private float height;

    private Integer pageNum;

    public Integer getPageNum() {
        return pageNum;
    }

    public void setPageNum(Integer pageNum) {
        this.pageNum = pageNum;
    }

    public float getX() {
        return x;
    }

    public void setX(float x) {
        this.x = x;
    }

    public float getY() {
        return y;
    }

    public void setY(float y) {
        this.y = y;
    }

    public float getWidth() {
        return width;
    }

    public void setWidth(float width) {
        this.width = width;
    }

    public float getHeight() {
        return height;
    }

    public void setHeight(float height) {
        this.height = height;
    }
}
  1. SignPdf 签章类
package com.zhiyis.framework.util;

import com.itextpdf.text.Image;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfSignatureAppearance;
import com.itextpdf.text.pdf.PdfSignatureAppearance.RenderingMode;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.security.*;
import com.itextpdf.text.pdf.security.MakeSignature.CryptoStandard;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

import java.io.*;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Security;
import java.security.cert.Certificate;
import java.util.UUID;

/**
 * 签印
 */
public class SignPdf {
    /**
     * @param password     秘钥密码
     * @param inputStream  秘钥文件
     * @param signPdfSrc   签名的PDF文件
     * @param signImage    签名图片文件
     * @param x            x坐标
     * @param y            y坐标
     * @return
     */
    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;
            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;
    }

}
  1. 工具方法
public static boolean uploadFile(byte[] file, String filePath) throws Exception {
    String tempPath = filePath.substring(0,filePath.lastIndexOf("/"));
    File targetFile = new File(tempPath);
    if(!targetFile.exists()) {
        boolean out = targetFile.mkdirs();
        if(out) {
            log.info(filePath + " create success");
        } else {
            log.info(filePath + " create fail");
        }
    }

    FileOutputStream out1 = new FileOutputStream(filePath);
    out1.write(file);
    out1.flush();
    out1.close();
    File f = new File(filePath);
    return f.exists();
}

总结

  1. 公私钥的生成网上很多就自己去生成吧
  2. 如果想要测试效果的可以把签章部分先去掉也可以运行
  3. 我觉得这篇博客是我最有含金量的一篇了~我找了很多博客定位pdf签章的没有靠谱的,很多技术实现都很复杂,我最初版本,也就是前面有一篇博客实现就是改编自网上一篇博客的,但是有很多问题,代码也过于复杂难懂,弯弯绕绕且难以修改增强。
  4. 我研究了官方最新代码结合自己脑洞大开的思路,精简出了很简单的三个类,其实排除实体类,真正实现功能就一个PdfParser
  5. **如果觉得有用给我点个赞哦^_^**