restful 大概： 

过 REST 风格体系架构，请求和响应都是基于资源表示的传输来构建的。资源是通过全局 ID 来标识的，这些 ID 一般使用的是一个统一资源标识符（URI）。 客户端应用使用 HTTP 方法（如，GET、POST、PUT 或 DELETE）来操作一个或多个资源。 通常，GET 是用于获取或列出一个或多个资源，POST 用于创建，PUT 用于更新或替换，而 DELETE 则用于删除资源。

Spring REST 支持的主要特性包括：

• 注释，如 @RequestMapping 和 @PathVariable，支持资源标识和 URL 映射
• ContentNegotiatingViewResolver 支持为不同的 MIME/内容类型使用不同的表示方式
• 使用相似的编程模型无缝地整合到原始的 MVC 层

@RequestMapping(value = "/{username}", method = RequestMethod.GET,                        headers = {"Accept=text/xml, application/json"})

public @ResponseBody        Spitter getSpitter(@PathVariable String username) {

return spitterService.getSpitter(username);        }

ContentNegotiatingViewResolver 先检查url，后检查header accept

 

HTTP message converters ：可以将method返回client需要的形式，

Assuming that the Jackson JSON library is in the appli- cation’s classpath, the object returned from the handler method will be given to the MappingJacksonHttpMessageConverter for conversion into a JSON representation to be returned to the client. On the other hand, if the request header indicates that the client prefers text/xml, then Jaxb2RootElementHttpMessageConverter will be tasked with producing an XML response to the client. 

 

 关于url 解析到view：  

 

@RequestBody:发送请求的data

@RequestMapping(value = "/{username}", method = RequestMethod.PUT,                headers = "Content-Type=application/json")

@ResponseStatus(HttpStatus.NO_CONTENT)public void updateSpitter(@PathVariable String username,

@RequestBody Spitter spitter) {  spitterService.saveSpitter(spitter);

}

When the request arrives, Spring MVC will see that the updateSpitter() is able to handle the request. But the message arrives as an XML document, and this method asks for a Spitter object. In this case, the MappingJacksonHttpMessageConverter may be chosen to convert the JSON message into a Spitter object. For that to work, the following criteria must be met:

? The request’s Content-Type header must be set to application/json.

? The Jackson JSON library must be available on the application’s classpath.