URLDecoder报错

URLDecoder.decode(param,"utf-8");

有时候会出现类似如下的错误：
URLDecoder异常Illegal hex characters in escape (%)

这是因为传参有一些特殊字符，比如%号或者说+号，导致不能解析，报错
解决方法是：
public static String replacer(StringBuffer outBuffer) {

  String data = outBuffer.toString();
  try {
     data = data.replaceAll("%(?![0-9a-fA-F]{2})", "%25");
     data = data.replaceAll("\\+", "%2B");
     data = URLDecoder.decode(data, "utf-8");
  } catch (Exception e) {
     e.printStackTrace();
  }
  return data;

}