HTTP status code

被一个问题耽搁了好久，最后才恍然。这是关于HTTP status的。

使用feign进行http请求，结果总是抛出异常: read 405.由于不了解feign具体原理，还总觉得是内部错误。虽然错误信息没有明确指出http返回异常，但看到405就应该敏感才对。这里就记录遇到的各种status。

 

1.405 Method Not Allowed

请求方式不允许。即服务端只允许比如get，而你使用post获取则返回405.

The method specified in the Request-Line is not allowed for the resource identified by the Request-URI. The response MUST include an Allow header containing a list of valid methods for the requested resource.

restful url的含义就是资源定位，所以请求的都是resource。通过get,post,delete,option等来确定对应的行为。当请求为request的时候，服务端会返回一个response。这个response的header会告诉你他允许的行为：

Allow →GET
Cache-Control →no-cache, no-store, max-age=0, must-revalidate
Content-Type →application/json;charset=UTF-8
Date →Wed, 03 Aug 2016 12:52:52 GMT
Expires →0
Pragma →no-cache
Strict-Transport-Security →max-age=31536000 ; includeSubDomains
Transfer-Encoding →chunked
X-Content-Type-Options →nosniff
X-Frame-Options →DENY
X-XSS-Protection →1; mode=block

比如服务端：

@RequestMapping(value = "/map.json", method = RequestMethod.GET)
    @ResponseBody
    public Map map(){
        Map map = new HashMap();
        map.put("name","Ryan");
        map.put("sex","man");
        map.put("age",18);
        List list = new ArrayList();
        list.add("red");
        list.add("black");
        list.add("blue");
        list.add("yellow");
        map.put("colors",list);
        return map;
    }

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