Java regular expression method to obtain and replace the specified attribute value of a specified HTML tag

public static String repDomain(String source, String domain, String element, String attr) {
 
    String img = "";
    Pattern p_image;
    Matcher m_image;
    String regEx_img = "<" + element + "[^<>]*?\\s" + attr + "=[&#39;\"]?(.*?)[&#39;\"]?(\\s.*?)?>";
    p_image = Pattern.compile(regEx_img, Pattern.CASE_INSENSITIVE);
    m_image = p_image.matcher(source);
    while (m_image.find()) {
      img = m_image.group();
      Matcher m = Pattern.compile("href\\s*=\\s*\"?(.*?)(\"|>|\\s+)").matcher(img);
      while (m.find()) {
        String srcVal = m.group(1);
        if(srcVal.indexOf("/@tenant")>=0){
            int idx = srcVal.indexOf("/@tenant");
            StringBuffer temp = new StringBuffer();
            String dstVal = temp.append(domain).append(srcVal.substring(idx+1)).toString();
            source = source.replace(srcVal, dstVal);
        }
      }
    }
    return source;
  }