With POI my solution is:
public static void merge(InputStream src1, InputStream src2, OutputStream dest) throws Exception {
OPCPackage src1Package = OPCPackage.open(src1);
OPCPackage src2Package = OPCPackage.open(src2);
XWPFDocument src1Document = new XWPFDocument(src1Package);
CTBody src1Body = src1Document.getDocument().getBody();
XWPFDocument src2Document = new XWPFDocument(src2Package);
CTBody src2Body = src2Document.getDocument().getBody();
appendBody(src1Body, src2Body);
src1Document.write(dest);
}
private static void appendBody(CTBody src, CTBody append) throws Exception {
XmlOptions optionsOuter = new XmlOptions();
optionsOuter.setSaveOuter();
String appendString = append.xmlText(optionsOuter);
String srcString = src.xmlText();
String prefix = srcString.substring(0,srcString.indexOf(">")+1);
String mainPart = srcString.substring(srcString.indexOf(">")+1,srcString.lastIndexOf("<"));
String sufix = srcString.substring( srcString.lastIndexOf("<") );
String addPart = appendString.substring(appendString.indexOf(">") + 1, appendString.lastIndexOf("<"));
CTBody makeBody = CTBody.Factory.parse(prefix+mainPart+addPart+sufix);
src.set(makeBody);
}
With Docx4j my solution is:
public class MergeDocx {
private static long chunk = 0;
private static final String CONTENT_TYPE = "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
public void mergeDocx(InputStream s1, InputStream s2, OutputStream os) throws Exception {
WordprocessingMLPackage target = WordprocessingMLPackage.load(s1);
insertDocx(target.getMainDocumentPart(), IOUtils.toByteArray(s2));
SaveToZipFile saver = new SaveToZipFile(target);
saver.save(os);
}
private static void insertDocx(MainDocumentPart main, byte[] bytes) throws Exception {
AlternativeFormatInputPart afiPart = new AlternativeFormatInputPart(new PartName("/part" + (chunk++) + ".docx"));
afiPart.setContentType(new ContentType(CONTENT_TYPE));
afiPart.setBinaryData(bytes);
Relationship altChunkRel = main.addTargetPart(afiPart);
CTAltChunk chunk = Context.getWmlObjectFactory().createCTAltChunk();
chunk.setId(altChunkRel.getId());
main.addObject(chunk);
}
}
