Spring @RequestMapping [英] Spring @RequestMapping

问题描述

我一直在 @RequestMapping 中看到这种参数 value =/ redirect / {id}春天的诠释。我一直在想这里的 {id} 是什么？这是某种表达语言？

I keep seeing this kind of param value = "/redirect/{id}" in a @RequestMapping annotation of the Spring. I keep wondering what is {id} here? Is this some sort of Expression Language?

我所看到的示例代码：

@RequestMapping( value = "/files/{id}", method = RequestMethod.GET )
public void getFile( @PathVariable( "id" )
String fileName, HttpServletResponse response )
{
    try
    {
         // get your file as InputStream
         InputStream is = new FileInputStream("/pathToFile/"+ fileName);
         // copy it to response's OutputStream
         IOUtils.copy( is, response.getOutputStream() );
         response.flushBuffer();
    }
    catch( IOException ex )
    {
         throw new RuntimeException( "IOError writing file to output stream" );
    }

}

我的问题是什么是 {id} 在映射中它与 @PathVariable 注释的关系以及如何使用它？我从网上获得了一些信息，但是我会更加欣赏你们听到更清楚的解释。

My question is what is the {id} in the mapping and what is its relationship with the @PathVariable annotation and how to use it? I red some info from the web but I will much more appreciate it to hear much more clearer explanation from you guys.

推荐答案

{foo} 部分在 @RequestMapping 值是一个路径变量，表示从url路径检索的值，而不是来自请求参数。

The {foo} part in a @RequestMapping value is a path variable which means a value retrieved from the url path and not from a request parameter.

例如，如果用户访问 /files/foo.zip ，则 {id} 将匹配 foo.zip 并告诉Spring将该值存储到具有注释<$ c的变量中$ c> @PathVariable（id）。

For example if the user access to /files/foo.zip, then {id} will match foo.zip and you tell Spring to store that value into the variable that has the annotation @PathVariable("id").

您可以在 @RequestMapping 注释值，您可以使用 @PathVariable 将这些值注入变量，并使用在大括号内使用的相同ID。

You can have multiple path variable in a URL identifier of a @RequestMapping annotation value, and you can inject these values into a variables by using @PathVariable with the same id you used inside the curly brackets.

这篇关于Spring @RequestMapping的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！