request.getHeader("User-Agent") 为空情况

[灰蛋一个]

请教 request.getHeader("User-Agent") 为空的情况 大虾

[花谢尊前不敢香]

getHeader java.lang.String getHeader(java.lang.String name) Returns the value of the specified request header as a String. If the request did not include a header of the specified name, this method returns null. If there are multiple headers with the same name, this method returns the first head in the request. The header name is case insensitive. You can use this method with any request header.

[owen1759]

把下面这个复制到命令行(cmd.exe)中，回车看结果

telnet localhost 80
GET / HTTP/1.1

任何header都是有可能没有的，何止是UA

[灰蛋一个]

引用 8 楼 fangmingshijie 的回复:

getHeader java.lang.String getHeader(java.lang.String name) Returns the value of the specified request header as a String. If the request did not include a header of the specified name, this method returns null. If there are multiple headers with the same name, this method returns the first head in the request. The header name is case insensitive. You can use this method with any request header.

If the request did not include a header of the specified name, this method returns null why did the request not include a header ???

[灰蛋一个]

人呢

[灰蛋一个]

顶

[ZHOU西口]

在jsp里？

[末日哥]

没用浏览器？

[灰蛋一个]

恩 浏览器里 咋访问的啊

[灰蛋一个]

@oh_Maxy 来看看

[灰蛋一个]

引用 3 楼 splendid_java 的回复:

在jsp里？

jsp里 就是index页面 判断用户的UA 为毛有为空的情况 ？