复制 DefaultStyledDocument

StyledDocuments 通常不实现克隆，因此如果有必要，必须以不同的方式复制它们。

try {
        //Initialization
        DefaultStyledDocument sourceDoc = new DefaultStyledDocument();
        DefaultStyledDocument destDoc = new DefaultStyledDocument();
        MutableAttributeSet bold = new SimpleAttributeSet();
        StyleConstants.setBold(bold, true);
        MutableAttributeSet italic = new SimpleAttributeSet();
        StyleConstants.setItalic(italic, true);
        sourceDoc.insertString(0, "Some bold text. ", bold);
        sourceDoc.insertString(sourceDoc.getLength(), "Some italic text", italic);
        
        //This does the actual copying
        String text = sourceDoc.getText(0, sourceDoc.getLength()); //This copies text, but loses formatting.
        for (int i = 0; i < text.length(); i++) {
            Element e = destDoc.getCharacterElement(i); //A Elment describes a particular part of a document, in this case a character
            AttributeSet attr = e.getAttributes(); //Gets the attributes for the character
            destDoc.insertString(destDoc.getLength(), text.substring(i, i+1), attr); //Gets the single character and sets its attributes from the element
        }
    } catch (BadLocationException ex) {
        //handle error
    }