request.getRemoteAddr方法为null

• 在单独servlet container 里，request.getRemoteAddr得到远程的ip地址，request.getRemoteHost()跟request.getRemoteAddr()一样
• jetty 代码片段

• public String getRemoteAddr()
      {
          if (_remoteAddr != null)
              return _remoteAddr;	
          return _endp==null?null:_endp.getRemoteAddr();
      }
  
      /* ------------------------------------------------------------ */
      /* 
       * @see javax.servlet.ServletRequest#getRemoteHost()
       */
      public String getRemoteHost()
      {
          if (_dns)
          {
              if (_remoteHost != null)
              {
                  return _remoteHost;
              }
              return _endp==null?null:_endp.getRemoteHost();
          }
          return getRemoteAddr();
      }

   
• 但通过apache做转发的话，一般request.getRemoteAddr==null,但apache一般是不会丢信息的，所以可以留心request里面head信息，一般可以通过request.getHeader( "x-forwarded-for" )得到remote ip