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Http请求中Content-Type讲解

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。

    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/vnd.ms-excel : excel文件格式
  • 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。

  1. 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。

  1. 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

Header解释示例
Accept指定客户端能够接收的内容类型Accept: text/plain, text/html
Accept-Charset浏览器可以接受的字符编码集。Accept-Charset: iso-8859-5
Accept-Encoding指定浏览器可以支持的web服务器返回内容压缩编码类型。Accept-Encoding: compress, gzip
Accept-Language浏览器可接受的语言Accept-Language: en,zh
Accept-Ranges可以请求网页实体的一个或者多个子范围字段Accept-Ranges: bytes
AuthorizationHTTP授权的授权证书Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Cache-Control指定请求和响应遵循的缓存机制Cache-Control: no-cache
Connection表示是否需要持久连接。(HTTP 1.1默认进行持久连接)Connection: close
CookieHTTP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。Cookie: $Version=1; Skin=new;
Content-Length请求的内容长度Content-Length: 348
Content-Type请求的与实体对应的MIME信息Content-Type: application/x-www-form-urlencoded
Date请求发送的日期和时间Date: Tue, 15 Nov 2010 08:12:31 GMT
Expect请求的特定的服务器行为Expect: 100-continue
From发出请求的用户的EmailFrom: user@email.com
Host指定请求的服务器的域名和端口号Host: www.zcmhi.com
If-Match只有请求内容与实体相匹配才有效If-Match: “737060cd8c284d8af7ad3082f209582d”
If-Modified-Since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If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT
If-None-Match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If-None-Match: “737060cd8c284d8af7ad3082f209582d”
If-Range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EtagIf-Range: “737060cd8c284d8af7ad3082f209582d”
If-Unmodified-Since只在实体在指定时间之后未被修改才请求成功If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT
Max-Forwards限制信息通过代理和网关传送的时间Max-Forwards: 10
Pragma用来包含实现特定的指令Pragma: no-cache
Proxy-Authorization连接到代理的授权证书Proxy-Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
Range只请求实体的一部分,指定范围Range: bytes=500-999
Referer先前网页的地址,当前请求网页紧随其后,即来路Referer: http://www.zcmhi.com/archives/71.html
TE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TE: trailers,deflate;q=0.5
Upgrade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)Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11
User-AgentUser-Agent的内容包含发出请求的用户信息User-Agent: Mozilla/5.0 (Linux; X11)
Via通知中间网关或代理服务器地址,通信协议Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warning关于消息实体的警告信息Warn: 199 Miscellaneous warning

Responses 部分

Header解释示例
Accept-Ranges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Accept-Ranges: bytes
Age从原始服务器到代理缓存形成的估算时间(以秒计,非负)Age: 12
Allow对某网络资源的有效的请求行为,不允许则返回405Allow: GET, HEAD
Cache-Control告诉所有的缓存机制是否可以缓存及哪种类型Cache-Control: no-cache
Content-Encodingweb服务器支持的返回内容压缩编码类型。Content-Encoding: gzip
Content-Language响应体的语言Content-Language: en,zh
Content-Length响应体的长度Content-Length: 348
Content-Location请求资源可替代的备用的另一地址Content-Location: /index.htm
Content-MD5返回资源的MD5校验值Content-MD5: Q2hlY2sgSW50ZWdyaXR5IQ==
Content-Range在整个返回体中本部分的字节位置Content-Range: bytes 21010-47021/47022
Content-Type返回内容的MIME类型Content-Type: text/html; charset=utf-8
Date原始服务器消息发出的时间Date: Tue, 15 Nov 2010 08:12:31 GMT
ETag请求变量的实体标签的当前值ETag: “737060cd8c284d8af7ad3082f209582d”
Expires响应过期的日期和时间Expires: Thu, 01 Dec 2010 16:00:00 GMT
Last-Modified请求资源的最后修改时间Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT
Location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Location: http://www.zcmhi.com/archives/94.html
Pragma包括实现特定的指令,它可应用到响应链上的任何接收方Pragma: no-cache
Proxy-Authenticate它指出认证方案和可应用到代理的该URL上的参数Proxy-Authenticate: Basic
refresh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)Refresh: 5; url=http://www.zcmhi.com/archives/94.html
Retry-After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Retry-After: 120
Serverweb服务器软件名称Server: Apache/1.3.27 (Unix) (Red-Hat/Linux)
Set-Cookie设置Http CookieSet-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1
Trailer指出头域在分块传输编码的尾部存在Trailer: Max-Forwards
Transfer-Encoding文件传输编码Transfer-Encoding:chunked
Vary告诉下游代理是使用缓存响应还是从原始服务器请求Vary: *
Via告知代理客户端响应是通过哪里发送的Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1)
Warning警告实体可能存在的问题Warning: 199 Miscellaneous warning
WWW-Authenticate表明客户端请求实体应该使用的授权方案WWW-Authenticate: Basic

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;


type有下面的形式

Text:用于标准化地表示的文本信息,文本消息可以是多种字符集和或者多种格式的; 
Multipart:用于连接消息体的多个部分构成一个消息,这些部分可以是不同类型的数据; 
Application:用于传输应用程序数据或者二进制数据; 
Message:用于包装一个E-mail消息; 
Image:用于传输静态图片数据; 
Audio:用于传输音频或者音声数据; 
Video:用于传输动态影像数据,可以是与音频编辑在一起的视频数据格式。 

实现文件下载

如果要想实现文件下载,可以在http的头中加入:

String filename = "template.xls";
response.setContentType("application/vnd.ms-excel;charset=utf8");   //xls文件
response.addHeader("Content-Disposition", "attachment;filename="
                    + new String(filename.getBytes(),"utf-8"));
-----------------
response.addHeader("Content-Disposition", "attachment;filename=template.xls");
-----------------
response.addHeader("Content-Length", "" + file.length());
OutputStream pos = new BufferedOutputStream(response.getOutputStream());

经过测试,html,pdf,gif等原来在网页中打开的文件都可以正常实现下载。

‘hqx’ => ‘application/mac-binhex40’,
‘cpt’ => ‘application/mac-compactpro’,
‘doc’ => ‘application/msword’,
‘bin’ => ‘application/octet-stream’,
‘dms’ => ‘application/octet-stream’,
‘lha’ => ‘application/octet-stream’,
‘lzh’ => ‘application/octet-stream’,
‘exe’ => ‘application/octet-stream’,
‘class’ => ‘application/octet-stream’,
‘so’ => ‘application/octet-stream’,
‘dll’ => ‘application/octet-stream’,
‘oda’ => ‘application/oda’,
‘pdf’ => ‘application/pdf’,
‘ai’ => ‘application/postscript’,
‘eps’ => ‘application/postscript’,
‘ps’ => ‘application/postscript’,
‘smi’ => ‘application/smil’,
‘smil’ => ‘application/smil’,
‘mif’ => ‘application/vnd.mif’,
‘xls’ => ‘application/vnd.ms-excel’,
‘ppt’ => ‘application/vnd.ms-powerpoint’,
‘wbxml’ => ‘application/vnd.wap.wbxml’,
‘wmlc’ => ‘application/vnd.wap.wmlc’,
‘wmlsc’ => ‘application/vnd.wap.wmlscriptc’,
‘bcpio’ => ‘application/x-bcpio’,
‘vcd’ => ‘application/x-cdlink’,
‘pgn’ => ‘application/x-chess-pgn’,
‘cpio’ => ‘application/x-cpio’,
‘csh’ => ‘application/x-csh’,
‘dcr’ => ‘application/x-director’,
‘dir’ => ‘application/x-director’,
‘dxr’ => ‘application/x-director’,
‘dvi’ => ‘application/x-dvi’,
‘spl’ => ‘application/x-futuresplash’,
‘gtar’ => ‘application/x-gtar’,
‘hdf’ => ‘application/x-hdf’,
‘js’ => ‘application/x-javascript’,
‘skp’ => ‘application/x-koan’,
‘skd’ => ‘application/x-koan’,
‘skt’ => ‘application/x-koan’,
‘skm’ => ‘application/x-koan’,
‘latex’ => ‘application/x-latex’,
‘nc’ => ‘application/x-netcdf’,
‘cdf’ => ‘application/x-netcdf’,
‘sh’ => ‘application/x-sh’,
‘shar’ => ‘application/x-shar’,
‘swf’ => ‘application/x-shockwave-flash’,
‘sit’ => ‘application/x-stuffit’,
‘sv4cpio’ => ‘application/x-sv4cpio’,
‘sv4crc’ => ‘application/x-sv4crc’,
‘tar’ => ‘application/x-tar’,
‘tcl’ => ‘application/x-tcl’,
‘tex’ => ‘application/x-tex’,
‘texinfo’ => ‘application/x-texinfo’,
‘texi’ => ‘application/x-texinfo’,
‘t’ => ‘application/x-troff’,
‘tr’ => ‘application/x-troff’,
‘roff’ => ‘application/x-troff’,
‘man’ => ‘application/x-troff-man’,
‘me’ => ‘application/x-troff-me’,
‘ms’ => ‘application/x-troff-ms’,
‘ustar’ => ‘application/x-ustar’,
‘src’ => ‘application/x-wais-source’,
‘xhtml’ => ‘application/xhtml+xml’,
‘xht’ => ‘application/xhtml+xml’,
‘zip’ => ‘application/zip’,
‘au’ => ‘audio/basic’,
‘snd’ => ‘audio/basic’,
‘mid’ => ‘audio/midi’,
‘midi’ => ‘audio/midi’,
‘kar’ => ‘audio/midi’,
‘mpga’ => ‘audio/mpeg’,
‘mp2’ => ‘audio/mpeg’,
‘mp3’ => ‘audio/mpeg’,
‘aif’ => ‘audio/x-aiff’,
‘aiff’ => ‘audio/x-aiff’,
‘aifc’ => ‘audio/x-aiff’,
‘m3u’ => ‘audio/x-mpegurl’,
‘ram’ => ‘audio/x-pn-realaudio’,
‘rm’ => ‘audio/x-pn-realaudio’,
‘rpm’ => ‘audio/x-pn-realaudio-plugin’,
‘ra’ => ‘audio/x-realaudio’,
‘wav’ => ‘audio/x-wav’,
‘pdb’ => ‘chemical/x-pdb’,
‘xyz’ => ‘chemical/x-xyz’,
‘bmp’ => ‘image/bmp’,
‘gif’ => ‘image/gif’,
‘ief’ => ‘image/ief’,
‘jpeg’ => ‘image/jpeg’,
‘jpg’ => ‘image/jpeg’,
‘jpe’ => ‘image/jpeg’,
‘png’ => ‘image/png’,
‘tiff’ => ‘image/tiff’,
‘tif’ => ‘image/tiff’,
‘djvu’ => ‘image/vnd.djvu’,
‘djv’ => ‘image/vnd.djvu’,
‘wbmp’ => ‘image/vnd.wap.wbmp’,
‘ras’ => ‘image/x-cmu-raster’,
‘pnm’ => ‘image/x-portable-anymap’,
‘pbm’ => ‘image/x-portable-bitmap’,
‘pgm’ => ‘image/x-portable-graymap’,
‘ppm’ => ‘image/x-portable-pixmap’,
‘rgb’ => ‘image/x-rgb’,
‘xbm’ => ‘image/x-xbitmap’,
‘xpm’ => ‘image/x-xpixmap’,
‘xwd’ => ‘image/x-xwindowdump’,
‘igs’ => ‘model/iges’,
‘iges’ => ‘model/iges’,
‘msh’ => ‘model/mesh’,
‘mesh’ => ‘model/mesh’,
‘silo’ => ‘model/mesh’,
‘wrl’ => ‘model/vrml’,
‘vrml’ => ‘model/vrml’,
‘css’ => ‘text/css’,
‘html’ => ‘text/html’,
‘htm’ => ‘text/html’,
‘asc’ => ‘text/plain’,
‘txt’ => ‘text/plain’,
‘rtx’ => ‘text/richtext’,
‘rtf’ => ‘text/rtf’,
‘sgml’ => ‘text/sgml’,
‘sgm’ => ‘text/sgml’,
‘tsv’ => ‘text/tab-separated-values’,
‘wml’ => ‘text/vnd.wap.wml’,
‘wmls’ => ‘text/vnd.wap.wmlscript’,
‘etx’ => ‘text/x-setext’,
‘xsl’ => ‘text/xml’,
‘xml’ => ‘text/xml’,
‘mpeg’ => ‘video/mpeg’,
‘mpg’ => ‘video/mpeg’,
‘mpe’ => ‘video/mpeg’,
‘qt’ => ‘video/quicktime’,
‘mov’ => ‘video/quicktime’,
‘mxu’ => ‘video/vnd.mpegurl’,
‘avi’ => ‘video/x-msvideo’,
‘movie’ => ‘video/x-sgi-movie’,
‘ice’ => ‘x-conference/x-cooltalk’,

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