package cn.home1.oss.lib.common;
   
   import static org.apache.commons.lang3.StringUtils.isBlank;
   
   import java.nio.charset.Charset;
   import java.nio.charset.StandardCharsets;
   
   import javax.servlet.ServletRequest;
   import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletRequestWrapper;
  
  /**
   * Created by zhanghaolun on 16/11/16.
   */
  public abstract class RequestUtlis {
  
    private RequestUtlis() {
    }
  
    public static Charset findCharset(final HttpServletRequest request) {
      final String encoding = request.getCharacterEncoding();
      final Charset result;
      if (isBlank(encoding)) {
        result = StandardCharsets.UTF_8;
      } else {
        result = Charset.forName(encoding);
      }
      return result;
    }
  
    @SuppressWarnings("unchecked")
    public static <T extends HttpServletRequestWrapper> T findWrapper( //
      final ServletRequest request, final Class<T> type //
    ) {
      final T result;
      if (request != null) {
        if (type.isAssignableFrom(request.getClass())) {
          result = (T) request;
        } else {
          if (HttpServletRequestWrapper.class.isAssignableFrom(request.getClass())) {
            return findWrapper(((HttpServletRequestWrapper) request).getRequest(), type);
          } else {
            result = null;
          }
        }
      } else {
        result = null;
      }
      return result;
    }
  }