java - ServletRequest.getRemoteAddr()返回的IP格式是什么

Question

ServletRequest.getRemoteAddr() 的 Javadoc没有提及返回的 IP 地址的格式。这在实现过滤器时很烦人。我们可以指望什么？有没有可以依赖的官方规范？谢谢。

Answer 1

让我们从 ServletRequest#getRemoteAddr() javadoc 开始:

getRemoteAddr

    java.lang.String getRemoteAddr()

Returns the Internet Protocol (IP) address of the client or last proxy that sent the request. For HTTP servlets, same as the value of the CGI variable REMOTE_ADDR.

(强调我的)

好吧，让我们阅读CGI REMOTE_ADDR spec :

4.1.8. REMOTE_ADDR

The REMOTE_ADDR variable MUST be set to the network address of the client sending the request to the server.

   REMOTE_ADDR  = hostnumber
   hostnumber   = ipv4-address | ipv6-address
   ipv4-address = 1*3digit "." 1*3digit "." 1*3digit "." 1*3digit
   ipv6-address = hexpart [ ":" ipv4-address ]
   hexpart      = hexseq | ( [ hexseq ] "::" [ hexseq ] )
   hexseq       = 1*4hex *( ":" 1*4hex )

The format of an IPv6 address is described in RFC 3513 [15].

那里，你有所有可能的格式。