PdfUtils.java

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.pdf.*;
import lombok.extern.slf4j.Slf4j;
import org.xhtmlrenderer.pdf.ITextFontResolver;
import org.xhtmlrenderer.pdf.ITextRenderer;

import java.io.*;
import java.util.List;
 
 
 @Slf4j
public class PdfUtils {
 public static void mergePdfFiles(List<byte[]> files, OutputStream outputStream)
        throws IOException, DocumentException {
        Document document = null;
        PdfCopy copy = null;
        try {
            document = new Document(new PdfReader(files.get(0)).getPageSize(1));
            copy = new PdfCopy(document, outputStream);
            document.open();
            for (byte[] file : files) {
                PdfReader reader = new PdfReader(file);
                int n = reader.getNumberOfPages();
                for (int j = 1; j <= n; j++) {
                    document.newPage();
                    PdfImportedPage page = copy.getImportedPage(reader, j);
                    copy.addPage(page);
                }
            }
        } finally {
            if (null != document && document.getPageNumber() > 0) {
                document.close();
            }
            if (copy != null) {
                copy.close();
            }
        }
    }
    
    
    
     /**
     * 使用 iText 生成 PDF 文档
     *
     * @param htmlTmpStr
     *            html 模板文件字符串
     * @param fontFile
     *            所需字体文件(相对路径+文件名)
     */
    public static byte[] createPDF(String htmlTmpStr, String fontFile) throws IOException, DocumentException {
        byte[] result;
        try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream();) {
            ITextRenderer renderer = new ITextRenderer();
            renderer.setDocumentFromString(htmlTmpStr);
            ITextFontResolver fontResolver = renderer.getFontResolver();
            // 解决中文支持问题,需要所需字体(ttc)文件
            fontResolver.addFont(ResourceFileUtil.getAbsolutePath(fontFile), BaseFont.IDENTITY_H,
                BaseFont.NOT_EMBEDDED);
            renderer.layout();
            renderer.createPDF(outputStream);
            result = outputStream.toByteArray();
            outputStream.flush();
        }
        return result;
    }
}