Http请求中Content-Type讲解以及在Spring MVC中的应用

我会带着你远行 2022-08-07 17:41 131阅读 0赞

引言： 在Http请求中，我们每天都在使用Content-type来指定不同格式的请求信息，但是却很少有人去全面了解content-type中允许的值有多少，这里将讲解Content-Type的可用值，以及在Spring MVC中如何使用它们来映射请求信息。

1.  Content-Type

MediaType，即是Internet Media Type，互联网媒体类型；也叫做MIME类型，在Http协议消息头中，使用Content-Type来表示具体请求中的媒体类型信息。

类型格式：type/subtype(;parameter)? type
      主类型，任意的字符串，如text，如果是*号代表所有； 
      subtype 子类型，任意的字符串，如html，如果是*号代表所有； 
      parameter 可选，一些参数，如Accept请求头的q参数， Content-Type的 charset参数。

例如： Content-Type: text/html;charset:utf-8;

常见的媒体格式类型如下：

*      text/html ： HTML格式
 *      text/plain ：纯文本格式       
    
 *      text/xml ：  XML格式
 *      image/gif ：gif图片格式     
    
 *      image/jpeg ：jpg图片格式  
    
 *      image/png：png图片格式

以application开头的媒体格式类型：

*     application/xhtml+xml ：XHTML格式
 *     application/xml     ： XML数据格式
 *     application/atom+xml  ：Atom XML聚合格式     
    
 *     application/json    ： JSON数据格式
 *     application/pdf       ：pdf格式   
    
 *     application/msword  ： Word文档格式
 *     application/octet-stream ： 二进制流数据（如常见的文件下载）
 *     application/x-www-form-urlencoded ： <form encType=””>中默认的encType，form表单数据被编码为key/value格式发送到服务器（表单默认的提交数据的格式）

另外一种常见的媒体格式是上传文件之时使用的：

*      multipart/form-data ： 需要在表单中进行文件上传时，就需要使用该格式

以上就是我们在日常的开发中，经常会用到的若干content-type的内容格式。

2.   Spring MVC中关于关于Content-Type类型信息的使用

首先我们来看看RequestMapping中的Class定义：

@Target({ElementType.METHOD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Mapping
    public @interface RequestMapping {
          String[] value() default {};
          RequestMethod[] method() default {};
          String[] params() default {};
          String[] headers() default {};
          String[] consumes() default {};
          String[] produces() default {};
    }

value:  指定请求的实际地址， 比如 /action/info之类。  
method：  指定请求的method类型， GET、POST、PUT、DELETE等  
consumes： 指定处理请求的提交内容类型（Content-Type），例如application/json, text/html;  
produces:    指定返回的内容类型，仅当request请求头中的(Accept)类型中包含该指定类型才返回  
params： 指定request中必须包含某些参数值是，才让该方法处理  
headers： 指定request中必须包含某些指定的header值，才能让该方法处理请求

其中，consumes， produces使用content-typ信息进行过滤信息；headers中可以使用content-type进行过滤和判断。

3. 使用示例

3.1 headers

@RequestMapping(value = "/test", method = RequestMethod.GET, headers="Referer=http://www.ifeng.com/")  
      public void testHeaders(@PathVariable String ownerId, @PathVariable String petId) {      
        // implementation omitted  
      }

这里的Headers里面可以匹配所有Header里面可以出现的信息，不局限在Referer信息。

示例2

@RequestMapping(value = "/response/ContentType", headers = "Accept=application/json")  
    public void response2(HttpServletResponse response) throws IOException {  
        //表示响应的内容区数据的媒体类型为json格式，且编码为utf-8(客户端应该以utf-8解码)  
        response.setContentType("application/json;charset=utf-8");  
        //写出响应体内容  
        String jsonData = "{\"username\":\"zhang\", \"password\":\"123\"}";  
        response.getWriter().write(jsonData);  
    }

服务器根据请求头“Accept=application/json”生产json数据。

当你有如下Accept头，将遵守如下规则进行应用：  
①Accept：text/html,application/xml,application/json  
      将按照如下顺序进行produces的匹配 ①text/html ②application/xml ③application/json  
②Accept：application/xml;q=0.5,application/json;q=0.9,text/html  
      将按照如下顺序进行produces的匹配 ①text/html ②application/json ③application/xml  
      参数为媒体类型的质量因子，越大则优先权越高(从0到1)  
③Accept：\*/\*,text/\*,text/html  
      将按照如下顺序进行produces的匹配 ①text/html ②text/\* ③\*/\*

即匹配规则为：最明确的优先匹配。

## Requests部分 ##

<table style=""> 
 <tbody style="margin:0px; padding:0px"> 
  <tr style="margin:0px; padding:0px"> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> Header</th> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> 解释</th> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> 示例</th> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 指定客户端能够接收的内容类型</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept: text/plain, text/html</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Charset</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 浏览器可以接受的字符编码集。</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Charset: iso-8859-5</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Encoding</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 指定浏览器可以支持的web服务器返回内容压缩编码类型。</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Encoding: compress, gzip</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Language</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 浏览器可接受的语言</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Language: en,zh</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Ranges</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 可以请求网页实体的一个或者多个子范围字段</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Ranges: bytes</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Authorization</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> HTTP授权的授权证书</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cache-Control</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 指定请求和响应遵循的缓存机制</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cache-Control: no-cache</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Connection</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 表示是否需要持久连接。（HTTP 1.1默认进行持久连接）</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Connection: close</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cookie</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> HTTP请求发送时，会把保存在该请求域名下的所有cookie值一起发送给web服务器。</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cookie: $Version=1; Skin=new;</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Length</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求的内容长度</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Length: 348</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Type</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求的与实体对应的MIME信息</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Type: application/x-www-form-urlencoded</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Date</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求发送的日期和时间</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Date: Tue, 15 Nov&nbsp;2010 08:12:31 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Expect</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求的特定的服务器行为</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Expect: 100-continue</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> From</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 发出请求的用户的Email</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> From: user@email.com</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Host</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 指定请求的服务器的域名和端口号</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Host: www.zcmhi.com</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Match</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 只有请求内容与实体相匹配才有效</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Match: “737060cd8c284d8af7ad3082f209582d”</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Modified-Since</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 如果请求的部分在指定时间之后被修改则请求成功，未被修改则返回304代码</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-None-Match</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 如果内容未改变返回304代码，参数为服务器先前发送的Etag，与服务器回应的Etag比较判断是否改变</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-None-Match: “737060cd8c284d8af7ad3082f209582d”</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Range</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 如果实体未改变，服务器发送客户端丢失的部分，否则发送整个实体。参数也为Etag</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Range: “737060cd8c284d8af7ad3082f209582d”</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Unmodified-Since</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 只在实体在指定时间之后未被修改才请求成功</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Max-Forwards</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 限制信息通过代理和网关传送的时间</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Max-Forwards: 10</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Pragma</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 用来包含实现特定的指令</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Pragma: no-cache</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Proxy-Authorization</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 连接到代理的授权证书</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Proxy-Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Range</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 只请求实体的一部分，指定范围</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Range: bytes=500-999</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Referer</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 先前网页的地址，当前请求网页紧随其后,即来路</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Referer: http://www.zcmhi.com/archives/71.html</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> TE</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 客户端愿意接受的传输编码，并通知服务器接受接受尾加头信息</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> TE: trailers,deflate;q=0.5</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Upgrade</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 向服务器指定某种传输协议以便服务器进行转换（如果支持）</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> User-Agent</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> User-Agent的内容包含发出请求的用户信息</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> User-Agent: Mozilla/5.0 (Linux; X11)</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Via</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 通知中间网关或代理服务器地址，通信协议</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Warning</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 关于消息实体的警告信息</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Warn: 199 Miscellaneous warning</td> 
  </tr> 
 </tbody> 
</table>

## Responses 部分     ##

<table style=""> 
 <tbody style="margin:0px; padding:0px"> 
  <tr style="margin:0px; padding:0px"> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> Header</th> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> 解释</th> 
   <th style="margin:0px; padding:3px; text-align:center; border:1px solid rgb(192,192,192); border-collapse:collapse; background:none 0px 0px repeat scroll rgb(237,239,240)"> 示例</th> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Ranges</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 表明服务器是否支持指定范围请求及哪种类型的分段请求</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Accept-Ranges: bytes</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Age</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 从原始服务器到代理缓存形成的估算时间（以秒计，非负）</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Age: 12</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Allow</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 对某网络资源的有效的请求行为，不允许则返回405</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Allow: GET, HEAD</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cache-Control</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 告诉所有的缓存机制是否可以缓存及哪种类型</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Cache-Control: no-cache</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Encoding</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> web服务器支持的返回内容压缩编码类型。</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Encoding: gzip</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Language</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 响应体的语言</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Language: en,zh</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Length</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 响应体的长度</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Length: 348</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Location</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求资源可替代的备用的另一地址</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Location: /index.htm</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-MD5</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 返回资源的MD5校验值</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-MD5: Q2hlY2sgSW50ZWdyaXR5IQ==</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Range</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 在整个返回体中本部分的字节位置</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Range: bytes 21010-47021/47022</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Type</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 返回内容的MIME类型</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Content-Type: text/html; charset=utf-8</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Date</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 原始服务器消息发出的时间</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Date: Tue, 15 Nov 2010 08:12:31 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> ETag</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求变量的实体标签的当前值</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> ETag: “737060cd8c284d8af7ad3082f209582d”</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Expires</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 响应过期的日期和时间</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Expires: Thu, 01 Dec 2010 16:00:00 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Last-Modified</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 请求资源的最后修改时间</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Location</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 用来重定向接收方到非请求URL的位置来完成请求或标识新的资源</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Location: http://www.zcmhi.com/archives/94.html</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Pragma</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 包括实现特定的指令，它可应用到响应链上的任何接收方</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Pragma: no-cache</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Proxy-Authenticate</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 它指出认证方案和可应用到代理的该URL上的参数</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Proxy-Authenticate: Basic</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> refresh</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 应用于重定向或一个新的资源被创造，在5秒之后重定向（由网景提出，被大部分浏览器支持）</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 
    <div style="margin:0px; padding:0px; font-size:14px; line-height:25.2000007629395px"> 
     <span style="font-family:monospace; margin:0px; padding:0px">&nbsp;</span> 
    </div> <p style="margin:5px 0px; padding:0px; font-family:verdana,Arial,Helvetica,sans-serif; font-size:14px; color:rgb(35,35,35)"> <span style="font-family:monospace; margin:0px; padding:0px">&nbsp;</span></p> 
    <div style="margin:0px; padding:0px; font-size:14px; line-height:25.2000007629395px"> 
     <span style="font-family:Georgia,'Times New Roman','Bitstream Charter',Times,serif; margin:0px; padding:0px">Refresh: 5; url=</span> 
    </div> 
    <div style="margin:0px; padding:0px; font-size:14px; line-height:25.2000007629395px"> 
     <span style="font-family:Georgia,'Times New Roman','Bitstream Charter',Times,serif; margin:0px; padding:0px">http://www.zcmhi.com/archives/94.html</span> 
    </div> </td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Retry-After</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 如果实体暂时不可取，通知客户端在指定时间之后再次尝试</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Retry-After: 120</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Server</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> web服务器软件名称</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Set-Cookie</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 设置Http Cookie</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Trailer</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 指出头域在分块传输编码的尾部存在</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Trailer: Max-Forwards</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Transfer-Encoding</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 文件传输编码</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> <span style="font-family:monospace; margin:0px; padding:0px"><span style="font-family:Georgia,'Times New Roman','Bitstream Charter',Times,serif; margin:0px; padding:0px">Transfer-Encoding:chunked</span></span></td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Vary</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 告诉下游代理是使用缓存响应还是从原始服务器请求</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Vary: *</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Via</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 告知代理客户端响应是通过哪里发送的</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Warning</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 警告实体可能存在的问题</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> Warning: 199 Miscellaneous warning</td> 
  </tr> 
  <tr style="margin:0px; padding:0px"> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> WWW-Authenticate</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> 表明客户端请求实体应该使用的授权方案</td> 
   <td style="margin:0px; padding:5px; line-height:21.6000003814697px; border:1px solid rgb(192,192,192); text-align:left; vertical-align:top; border-collapse:collapse"> WWW-Authenticate: Basic</td> 
  </tr> 
 </tbody> 
</table>

3.2 params的示例

@RequestMapping(value = "/test/{userId}", method = RequestMethod.GET, params="myParam=myValue")  
      public void findUser(@PathVariable String userId) {      
        // implementation omitted  
      }

仅处理请求中包含了名为“myParam”，值为“myValue”的请求，起到了一个过滤的作用。

3.3 consumes/produces

@Controller  
        @RequestMapping(value = "/users", method = RequestMethod.POST, consumes="application/json", produces="application/json")  
        @ResponseBody
        public List<User> addUser(@RequestBody User userl) {      
            // implementation omitted  
            return List<User> users;
        }

方法仅处理request Content-Type为“application/json”类型的请求. produces标识==>处理request请求中Accept头中包含了"application/json"的请求，同时暗示了返回的内容类型为application/json;

4. 总结

在本文中，首先介绍了Content-Type主要支持的格式内容，然后基于@RequestMapping标注的内容介绍了主要的使用方法，其中,headers, consumes,produces,都是使用Content-Type中使用的各种媒体格式内容，可以基于这个格式内容来进行访问的控制和过滤。

参考资料：

1.  HTTP中支持的Content-Type: http://tool.oschina.net/commons

2.  Media Type介绍。 http://www.iteye.com/topic/1127120