content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.nacos.core.utils;
  
  import org.apache.commons.lang3.StringUtils;
  
  import javax.servlet.http.HttpServletRequest;
  import java.io.UnsupportedEncodingException;
  import java.nio.charset.StandardCharsets;
  
  /**
   * @author nkorange
   */
  public class WebUtils {
  
      public static String required(HttpServletRequest req, String key) {
          String value = req.getParameter(key);
          if (StringUtils.isEmpty(value)) {
              throw new IllegalArgumentException("Param '" + key + "' is required.");
          }
  
          String encoding = req.getParameter("encoding");
          if (!StringUtils.isEmpty(encoding)) {
              try {
                  value = new String(value.getBytes(StandardCharsets.UTF_8), encoding);
              } catch (UnsupportedEncodingException ignore) {
              }
          }
  
          return value.trim();
      }
  
      public static String optional(HttpServletRequest req, String key, String defaultValue) {
  
          if (!req.getParameterMap().containsKey(key) || req.getParameterMap().get(key)[0] == null) {
              return defaultValue;
          }
  
          String value = req.getParameter(key);
  
          if (StringUtils.isBlank(value)) {
              return defaultValue;
          }
  
          String encoding = req.getParameter("encoding");
          if (!StringUtils.isEmpty(encoding)) {
              try {
                  value = new String(value.getBytes(StandardCharsets.UTF_8), encoding);
              } catch (UnsupportedEncodingException ignore) {
              }
          }
  
          return value.trim();
      }
  
      public static String getAcceptEncoding(HttpServletRequest req) {
          String encode = StringUtils.defaultIfEmpty(req.getHeader("Accept-Charset"), "UTF-8");
          encode = encode.contains(",") ? encode.substring(0, encode.indexOf(",")) : encode;
          return encode.contains(";") ? encode.substring(0, encode.indexOf(";")) : encode;
      }
  }
  