准备文档如下

image.png

import org.apache.commons.io.FileUtils;
import org.docx4j.openpackaging.packages.WordprocessingMLPackage;
import org.docx4j.openpackaging.parts.Part;
import org.docx4j.openpackaging.parts.PartName;
import org.docx4j.openpackaging.parts.WordprocessingML.BinaryPartAbstractImage;
import org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart;
import java.io.*;
import java.util.Collection;
import java.util.zip.CRC32;
import java.util.zip.Checksum;

public class ImageReplacement {
    public static void main(String[] args) throws Exception {
        File source = getFileFromUserDir("/template/template.docx");
        WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.load(source);
        MainDocumentPart documentPart = wordMLPackage.getMainDocumentPart();
        // 1610171220 为约定好的图片CheckSum数值
        BinaryPartAbstractImage imagePart = findBinaryPartAbstractImageByChecksum(1610171220, wordMLPackage);
        PartName partName = imagePart.getPartName();
        String rid = documentPart.getRelationshipsPart().getRel(partName).getId();
        documentPart.getRelationshipsPart().removePart(partName);
        BinaryPartAbstractImage insertImagePart = BinaryPartAbstractImage.createImagePart(wordMLPackage, getInsertImage());
        insertImagePart.getRels().get(0).setId(rid);
        wordMLPackage.addTargetPart(insertImagePart);
        wordMLPackage.save(new java.io.File("out.docx"));
    }

    private static File getFileFromUserDir(String path) {
        String dir = System.getProperty("user.dir");
        return new File(dir + path);
    }
    private static byte[] getInsertImage() throws IOException {
        File file =  getFileFromUserDir("/images/replacement.jpeg");
        return FileUtils.readFileToByteArray(file);
    }

    private static BinaryPartAbstractImage findBinaryPartAbstractImageByChecksum(long sum, WordprocessingMLPackage wordMLPackage) {
        Collection<Part> parts = wordMLPackage.getParts().getParts().values();
        for (Part part : parts) {
            if (part instanceof BinaryPartAbstractImage) {
                BinaryPartAbstractImage imagePart = (BinaryPartAbstractImage) part;
                byte[] bytes = imagePart.getBytes();
                if (isCheckSumEqual(sum, bytes)) {
                    return imagePart;
                }
            }
        }
        return null;
    }

    private static boolean isCheckSumEqual(long sum, byte[] bytes) {
        Checksum crc32 = new CRC32();
        crc32.update(bytes, 0, bytes.length);
        return crc32.getValue() == sum;
    }
}

输出如下

image.png