转义字符

public static String escapeControlCode (String text) {
    if ( text == null ) return "null";


    StringBuilder tmp = new StringBuilder(text.length());
    for ( int i=0; i<text.length(); i++ ) {
      int cp = text.codePointAt(i);
      if(cp < 0x0020)  {
        tmp.append(String.format("\\U%04X", cp));
      } else {
        tmp.append((char)cp);
      }
    }
    return tmp.toString();
  }