IssueDemo.java

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.pdmodel.PDResources;
import org.apache.pdfbox.pdmodel.font.PDFont;
import org.apache.pdfbox.pdmodel.font.PDType0Font;
import org.apache.pdfbox.pdmodel.interactive.form.PDField;
import org.apache.pdfbox.pdmodel.interactive.form.PDTextField;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Iterator;

public class IssueDemo {
    public static void main(String[] args) throws IOException {
        PDDocument doc = PDDocument.load(new File("i-130.pdf"));

        PDResources res = doc.getDocumentCatalog().getAcroForm().getDefaultResources();
        PDFont font = PDType0Font.load(doc, new FileInputStream(new File("NotoSansCJKsc-Medium.ttf")), false);
        String fontName = res.add(font).getName();

        long start = System.currentTimeMillis();
        for (Iterator<PDField> it = doc.getDocumentCatalog().getAcroForm().getFieldIterator(); it.hasNext(); ) {
            PDField field = it.next();
            if (field instanceof PDTextField) {
                PDTextField textField = (PDTextField) field;
                textField.setDefaultAppearance("/" + fontName + " 0 Tf 0 g");
                textField.setValue("中国");
                long end = System.currentTimeMillis();
                System.out.println("Filled " + textField.getFullyQualifiedName() + " in " + (end - start) + "ms");
                start = end;
            }
        }

        doc.save(new File("i-130-filled.pdf"));
    }
}

i-130-filled.pdf

i-130.pdf

NotoSansCJKsc-Medium.ttf