private String prefix(boolean isInput) {
    char[] buffer = new char[queryStack * 2 + 2];
    Arrays.fill(buffer, '=');
    buffer[queryStack * 2 + 1] = ' ';
    if (isInput) {
      buffer[queryStack * 2] = '>';
    } else {
      buffer[0] = '<';
    }
    return new String(buffer);
  }
Base class for proxies to do logging

@author Clinton Begin
@author Eduardo Macarron
src/main/java/org/apache/ibatis/logging/jdbc/BaseJdbcLogger.java