docx4j find and replace

Question

I have docx document with some placeholders. Now I should replace them with other content and save new docx document. I started with docx4j and found this method:

Answer 1

I created a library to publish my solution because it's quite a lot of code: https://github.com/phip1611/docx4j-search-and-replace-util

The workflow is the following:

First step:

// (this method was part of your question)  
List texts = getAllElementFromObject(docxDocument.getMainDocumentPart(), Text.class);

This way we get all actual Text-content in the correct order but without style markup in-between. We can edit the Text-objects (by setValue) and keep styles.

Resulting problem: Search-text/placeholders can be split accoss multiple Text-instances (because there can be style markup that is invisble in-between in original document), e.g. ${FOOBAR}, ${ + FOOBAR}, or $ + {FOOB + AR}

Second step:

Concat all Text-objects to a full string / "complete string"

Optional completeStringOpt = texts.stream().map(Text::getValue).reduce(String::concat);

Third step:

Create a class TextMetaItem. Each TextMetaItem knows for it's Text-object where it's content begins and ends in the complete string. E.g. If the Text-objects for "foo" and "bar" results in the complete string "foobar" than indices 0-2 belongs to "foo"-Text-object and 3-5 to "bar"-Text-object. Build a List

static List buildMetaItemList(List texts) {
    final int[] index = {0};
    final int[] iteration = {0};
    List list = new ArrayList<>();
    texts.forEach(text -> {
        int length = text.getValue().length();
        list.add(new TextMetaItem(index[0], index[0] + length - 1, text, iteration[0]));
        index[0] += length;
        iteration[0]++;
    });
    return list;
}

Fourth step:

Build a Map where the key is the index/char in the complete string. This means the map's length equals completeString.length()

static Map buildStringIndicesToTextMetaItemMap(List texts) {
    List metaItemList = buildMetaItemList(texts);
    Map map = new TreeMap<>();
    int currentStringIndicesToTextIndex = 0;
    // + 1 important here! 
    int max = metaItemList.get(metaItemList.size() - 1).getEnd() + 1;
    for (int i = 0; i < max; i++) {
        TextMetaItem currentTextMetaItem = metaItemList.get(currentStringIndicesToTextIndex);
        map.put(i, currentTextMetaItem);
        if (i >= currentTextMetaItem.getEnd()) {
            currentStringIndicesToTextIndex++;
        }
    }
    return map;
}

interim result:

Now you have enough metadata to delegate every action you want to do on the complete string to the corresponding Text object! (To change the content of Text-objects you just need to call (#setValue()) That's all what's needed in Docx4J to edit text. All style info etc will be preserved!

last step: search and replace

1. build a method that finds all occurrences of your possible placeholders. You should create a class like FoundResult(int start, int end) that stores begin and end indices of a found value (placeholder) in the complete string

   public static List findAllOccurrencesInString(String data, String search) {
       List list = new ArrayList<>();
       String remaining = data;
       int totalIndex = 0;
       while (true) {
           int index = remaining.indexOf(search);
           if (index == -1) {
               break;
           }
   
           int throwAwayCharCount = index + search.length();
           remaining = remaining.substring(throwAwayCharCount);
   
           list.add(new FoundResult(totalIndex + index, search));
   
           totalIndex += throwAwayCharCount;
       }
       return list;
   } 
   

   using this I build a new list of ReplaceCommands. A ReplaceCommand is a simple class and stores a FoundResult and the new value.

2. next you must order this list from the last item to the first (order by position in complete string)

3. now you can write a replace all algorithm because you know what action needs to be done on which Text-object. We did (2) so that replace operations won't invalidate indices of other FoundResults.

   3.1.) find Text-object(s) that needs to be changed 3.2.) call getValue() on them 3.3.) edit the string to the new value 3.4.) call setValue() on the Text-objects

This is the code that does all the magic. It executes a single ReplaceCommand.

   /**
     * @param texts All Text-objects
     * @param replaceCommand Command
     * @param map Lookup-Map from index in complete string to TextMetaItem
     */
    public static void executeReplaceCommand(List texts, ReplaceCommand replaceCommand, Map map) {
        TextMetaItem tmi1 = map.get(replaceCommand.getFoundResult().getStart());
        TextMetaItem tmi2 = map.get(replaceCommand.getFoundResult().getEnd());
        if (tmi2.getPosition() - tmi1.getPosition() > 0) {
            // it can happen that text objects are in-between
            // we can remove them (set to null)
            int upperBorder = tmi2.getPosition();
            int lowerBorder = tmi1.getPosition() + 1;
            for (int i = lowerBorder; i < upperBorder; i++) {
                texts.get(i).setValue(null);
            }
        }

       if (tmi1.getPosition() == tmi2.getPosition()) {
            // do replacement inside a single Text-object

            String t1 = tmi1.getText().getValue();
            int beginIndex = tmi1.getPositionInsideTextObject(replaceCommand.getFoundResult().getStart());
            int endIndex = tmi2.getPositionInsideTextObject(replaceCommand.getFoundResult().getEnd());

            String keepBefore = t1.substring(0, beginIndex);
            String keepAfter = t1.substring(endIndex + 1);

            tmi1.getText().setValue(keepBefore + replaceCommand.getNewValue() + keepAfter);
        } else {
            // do replacement across two Text-objects

            // check where to start and replace 
            // the Text-objects value inside both Text-objects
            String t1 = tmi1.getText().getValue();
            String t2 = tmi2.getText().getValue();

            int beginIndex = tmi1.getPositionInsideTextObject(replaceCommand.getFoundResult().getStart());
            int endIndex = tmi2.getPositionInsideTextObject(replaceCommand.getFoundResult().getEnd());

            t1 = t1.substring(0, beginIndex);
            t1 = t1.concat(replaceCommand.getNewValue());
            t2 = t2.substring(endIndex + 1);

            tmi1.getText().setValue(t1);
            tmi2.getText().setValue(t2);
        }
    }