重定向Httpstatuscode303和302
http302
http303
Http302
302是一个普通的重定向代码。直观的看来是,请求者(浏览器或者模拟http请求)发起一个请求,然后服务端重定向到另一个地址。而事实上,服务端仅仅是增加一条属性到header,location=重定向地址。而一般的,浏览器会自动的再去请求这个location,重新获取资源。也就是说,这个会使得浏览器发起两次请求。
Example
Clientrequest:
GET/index.htmlHTTP/1.1
Host:www.example.com
Serverresponse:
HTTP/1.1302Found
Location:http://www.iana.org/domains/example/
实验
首先,我们用一个Map来存储信息,key为username,value为随机数。
当我请求list的时候,跳转到users,来获取所有的用户。
Mapusers=newHashMap<>();
@RequestMapping(value="/list",method=RequestMethod.GET)
publicStringindex(){
return"redirect:/users";
}
@ResponseBody
@RequestMapping(value="/users",method=RequestMethod.GET)
publicResponseEntitygetUsers(){
ResponseEntityresponseEntity=newResponseEntity(users,HttpStatus.OK);
returnresponseEntity;
}
当时用浏览器访问的时候,会明显的看到浏览器地址变了,也就是说我明明请求的是list,结果你给我变成了users。然而,由于浏览器帮我们做了跳转的工作,我们感觉不出来,但从地址栏还是可以看到的。
查看
通过拦截请求可以看出来,访问了两次:
并且list是302,而users是200.也就是说list进行了重定向。再来看list的response:
RequestURL:https://localhost:8443/list
RequestMethod:GET
StatusCode:302
RemoteAddress:127.0.0.1:8888
ResponseHeaders
viewsource
Cache-Control:no-cache,no-store,max-age=0,must-revalidate
Content-Language:zh-CN
Content-Length:0
Date:Thu,08Sep201614:31:33GMT
Expires:0
Location:https://localhost:8443/users
Pragma:no-cache
Strict-Transport-Security:max-age=31536000;includeSubDomains
X-Application-Context:application:dev:8443
X-Content-Type-Options:nosniff
X-Frame-Options:DENY
X-XSS-Protection:1;mode=block
RequestHeaders
viewsource
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Accept-Encoding:gzip,deflate,sdch,br
Accept-Language:zh-CN,zh;q=0.8
Authorization:BasicYWRtaW46dGVzdA==
Connection:keep-alive
Host:localhost:8443
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0(WindowsNT10.0;WOW64)AppleWebKit/537.36(KHTML,likeGecko)Chrome/52.0.2743.82Safari/537.36
最关键的就是location:
Location:https://localhost:8443/users
浏览器获取到这个资源定位后就GET访问获取。所以users的请求是这样的:
RequestURL:https://localhost:8443/users
RequestMethod:GET
StatusCode:200
RemoteAddress:127.0.0.1:8888
ResponseHeaders
viewsource
Cache-Control:no-cache,no-store,max-age=0,must-revalidate
Content-Type:application/json;charset=UTF-8
Date:Thu,08Sep201614:31:33GMT
Expires:0
Pragma:no-cache
Strict-Transport-Security:max-age=31536000;includeSubDomains
Transfer-Encoding:chunked
X-Application-Context:application:dev:8443
X-Content-Type-Options:nosniff
X-Frame-Options:DENY
X-XSS-Protection:1;mode=block
RequestHeaders
viewsource
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,/;q=0.8
Accept-Encoding:gzip,deflate,sdch,br
Accept-Language:zh-CN,zh;q=0.8
Authorization:BasicYWRtaW46dGVzdA==
Connection:keep-alive
Host:localhost:8443
Upgrade-Insecure-Requests:1
User-Agent:Mozilla/5.0(WindowsNT10.0;WOW64)AppleWebKit/537.36(KHTML,likeGecko)Chrome/52.0.2743.82Safari/537.36
redirect的另一个作用是原请求的内容将会被舍弃,即如果是post请求,redirect的时候默认是不带参数的。与之相对应的forward的请求是转发,只有一次请求,并且带body转发过去。
Http303
303SeeOther。通常是指所请求的资源在别的地方,并且同302一样,会在header中的location标明资源的位置。在我的一个是使用过程中,我想要创建一个user,当关于这个user的key已经存在的时候,server将返回303,并且告之这个user的获取位置。
Example
Clientrequest:
POST/HTTP/1.1
Host:www.example.com
Serverresponse:
HTTP/1.1303SeeOther
Location:http://example.org/other
实验
我将要发送post请求创建user,如果user已经存在则返回303
Mapusers=newHashMap<>();
@ResponseBody
@RequestMapping(value="/users",method=RequestMethod.POST)
publicResponseEntitycreateUser(Stringusername){
DoubleluckNum=users.get(username);
if(luckNum==null){
doublerandom=Math.random();
users.put(username,random);
returnnewResponseEntity(random,HttpStatus.OK);
}else{
MultiValueMapheaders=newHttpHeaders();
headers.add("Location","/users/"+username);
returnnewResponseEntity(luckNum,headers,HttpStatus.SEE_OTHER);
}
}
@ResponseBody
@RequestMapping(value="/users/{username}",method=RequestMethod.GET)
publicResponseEntitygetUser(@PathVariable("username")Stringusername){
ResponseEntityresponseEntity=newww.baiyuewang.netResponseEntity("I''muser,Mynameis"+username+"Andmylucknumis"+users.get(username),HttpStatus.OK);
returnresponseEntity;
}
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