<dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>itextpdf</artifactId>
            <version>5.5.13.2</version>
        </dependency>

        <dependency>
            <groupId>com.itextpdf</groupId>
            <artifactId>itext-asian</artifactId>
            <version>5.2.0</version>
        </dependency>

  // 讀取本地文件，當(dāng)然線上環(huán)境肯定不這么寫
  PdfReader reader = new PdfReader("C:\\Users\\User\\Desktop\\開票預(yù)覽模板.pdf");
  // 線上環(huán)境使用了s3服務(wù)器，會(huì)提前得到字節(jié)流 byte[] bytes
  PdfReader reader = new PdfReader(bytes);

        // 臨時(shí)輸出流-表單
        ByteArrayOutputStream bos1 = new ByteArrayOutputStream();
        PdfStamper stamper = new PdfStamper(reader, bos1);


        // 獲取表單
        AcroFields form = stamper.getAcroFields();
        form.setGenerateAppearances(true);

        // 表單填充
        form.setField("purName","購(gòu)買方對(duì)應(yīng)公司");
        stamper.close();

// 最簡(jiǎn)單的示例
import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfWriter;

import java.io.FileOutputStream;

public class AdjustTablePositionInPdf {
    public static void main(String[] args) {
        try {
            // 創(chuàng)建一個(gè)新的 PDF 文檔
            Document document = new Document(PageSize.A4);
            PdfWriter.getInstance(document, new FileOutputStream("C:\\Users\\User\\Desktop\\adjusted_table_position.pdf"));
            document.open();

            // 添加文本內(nèi)容
            document.add(new Paragraph("Test PDF with Table"));

            // 創(chuàng)建表格
            PdfPTable table = new PdfPTable(2);
            table.addCell("Name");
            table.addCell("Age");
            table.addCell("Alice");
            table.addCell("25");
            table.addCell("Bob");
            table.addCell("30");

            // 設(shè)置表格之前的間距
            table.setSpacingBefore(20f);

            // 設(shè)置表格之后的間距
            table.setSpacingAfter(20f);

            // 設(shè)置表格的總寬度
            table.setTotalWidth(300f);

            // 將表格添加到 PDF
            document.add(table);

            document.close();

            System.out.println("PDF 文件生成成功！");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

/**
*  表頭信息
**/

@Data
@AllArgsConstructor
public class HeadRowMetaInfo {
    // 列中文名
    private String colName;
    // 列key
    private String colKey;
    // 列寬度
    private float width;
}

    /**
     * 自定義頭部信息
     * @return
     */
    public static List<HeadRowMetaInfo> headInfos(){
        List<HeadRowMetaInfo> infos = new ArrayList<>();
        infos.add(new HeadRowMetaInfo("貨物或應(yīng)稅勞務(wù)、服務(wù)名稱","commodityName",80));
        infos.add(new HeadRowMetaInfo("規(guī)格型號(hào)","model",80));
        infos.add(new HeadRowMetaInfo("單位","pushUnitName",80));
        infos.add(new HeadRowMetaInfo("數(shù)量","orderNum",80));
        infos.add(new HeadRowMetaInfo("單價(jià)","orderPriceNoTax",80));
        infos.add(new HeadRowMetaInfo("不含稅金額","orderAmount",80));
        infos.add(new HeadRowMetaInfo("稅額","taxAmt",80));
        infos.add(new HeadRowMetaInfo("含稅金額","orderAmountTax",80));
        infos.add(new HeadRowMetaInfo("稅率","taxRate",80));
        return infos;
    }

        // 臨時(shí)文件流-商品
        ByteArrayOutputStream bos2 = new ByteArrayOutputStream();

        // 獲取原頁(yè)面的尺寸和樣式
        Document document = new Document(reader.getPageSize(1));
        PdfWriter writer = PdfWriter.getInstance(document, bos2);

        document.open();
        //新創(chuàng)建一頁(yè)來(lái)存放后面生成的表格
        document.newPage();

        // 獲取商品導(dǎo)出數(shù)據(jù)
        List<Map<String, Object>> mapData = otherService.getData();
        // 全局統(tǒng)一字體，不設(shè)置無(wú)法顯示中文
        // 創(chuàng)建支持中文的字體
        BaseFont bfChinese = BaseFont.createFont("STSongStd-Light", "UniGB-UCS2-H", false);
        Font font = new Font(bfChinese, 12, Font.NORMAL, BaseColor.BLACK);

        PdfPTable table = generatePdfPTable(720f,font,mapData,headInfos());

        document.add(table);
        // 文檔流關(guān)閉
        // 關(guān)閉后才會(huì)觸發(fā)ByteArrayOutputStream的流更新
        document.close();
        writer.close();

    public static PdfPTable generatePdfPTable(float totalWidth, Font font, List<Map<String, Object>> data, List<HeadRowMetaInfo> headRowMetaInfos) throws DocumentException {
        // 多少列
        PdfPTable table = new PdfPTable(headRowMetaInfos.size());
        // 表寬度
        table.setTotalWidth(totalWidth);

        // 設(shè)置每列的寬度
        List<Float> flist = headRowMetaInfos.stream().map(HeadRowMetaInfo::getWidth).collect(Collectors.toList());
        float[] farr = new float[flist.size()];
        for(int i = 0;i<flist.size();i++){
            farr[i] = flist.get(i);
        }
        table.setWidths(farr);

        Map<Integer,String> indexToKeyMap = new HashMap<>();
        // 根據(jù)表頭信息插入表頭
        for(int i = 0 ;i < headRowMetaInfos.size();i++){
            table.addCell(new Phrase(headRowMetaInfos.get(i).getColName(),font));
            indexToKeyMap.put(i,headRowMetaInfos.get(i).getColKey());
        }

        // 添加行數(shù)據(jù)
        for(Map<String,Object> dataItem:data){
            for(int i=0;i<headRowMetaInfos.size();i++){
                if(dataItem.get(indexToKeyMap.get(i)) != null){
                    table.addCell(new Phrase(dataItem.get(indexToKeyMap.get(i)).toString(),font));
                }else{
                    table.addCell("-");
                }
            }
        }

        // 計(jì)算表格在頁(yè)面上的位置并添加到頁(yè)面
        // 注意：這里的坐標(biāo)可能需要根據(jù)實(shí)際情況調(diào)整
        table.setLockedWidth(true);
        return table;
    }

    public static byte[] copy(List<byte[]> files) throws DocumentException, IOException {
        // 創(chuàng)建文檔對(duì)象
        Document document = new Document();
        // 創(chuàng)建PdfCopy對(duì)象
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        PdfCopy copy = new PdfCopy(document, bos);
        // 設(shè)置只讀
        copy.setEncryption(null, null, PdfWriter.ALLOW_PRINTING, PdfWriter.STANDARD_ENCRYPTION_128);


        // 打開文檔
        document.open();
        PdfReader reader;
        int n;
        // 循環(huán)遍歷所有PDF文件
        for (byte[] file : files) {
            reader = new PdfReader(file);
            // 獲取每個(gè)PDF文件的頁(yè)數(shù)
            n = reader.getNumberOfPages();
            for (int page = 0; page < n; ) {
                // 向PdfCopy添加每一頁(yè)
                copy.addPage(copy.getImportedPage(reader, ++page));
            }
            // 關(guān)閉PdfReader
            reader.close();
        }

        // 關(guān)閉文檔，否則輸出流不會(huì)刷新
        document.close();

        byte[] bytes = bos.toByteArray();

        // 關(guān)閉流
        bos.close();
        return bytes;
    }

        log.info(returnPath +" pdf模板填充成功，進(jìn)行合并");
        List<byte[]> files = new ArrayList<>();
        files.add(bos1.toByteArray());
        files.add(bos2.toByteArray());
        // 合并兩個(gè)pdf流
        byte[] s3bytes = copy(files);

        // 關(guān)閉流
        bos1.close();
        bos2.close();
        reader.close();

        // 有流之后 可以把流存儲(chǔ)至本地文件，也可以上傳s3了
        String outputPath = "C:\\Users\\User\\Desktop\\test3.pdf";
        FileOutputStream fileOutputStream = new FileOutputStream(outputPath);
        fileOutputStream.write(s3bytes);
        fileOutputStream.close();