Ajax中的setRequestHeader设置请求头

Ajax中的setRequestHeader设置请求头

1、问题引发点:

前不久发现一个问题: 前端并没有设置请求头信息里面的Accept-Encoding:gzip...但是在请求头中可以明显的看到Accept-Encoding:gzip, deflate, sdch,并且我尝试修改这个请求头，发现 不 生 效；

2、XMLHttpRequest对象提供了一个设置请求头的方法:setRequestHeader，对应的jQuery可以再beforeSend回调里面设置请求头：

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$.ajax({     type: "GET",     url: "test.php",     success: function(data) {         console.log(data);     },     beforeSend: function(xhr) {         xhr.setRequestHeader("User-Agent", "headertest");     } });

3、后来看W3C标准文档发现，这个请求头不是什么都可以设置的，标准里面明确规定了以下请求头信息是浏览器控制，开发者不允许设置这些请求头

Terminate these steps if header is a case-insensitive match for one of the following headers:

• Accept-Charset
• Accept-Encoding
• Access-Control-Request-Headers
• Access-Control-Request-Method
• Connection
• Content-Length
• Cookie
• Cookie2
• Date
• DNT
• Expect
• Host
• Keep-Alive
• Origin
• Referer
• TE
• Trailer
• Transfer-Encoding
• Upgrade
• User-Agent
• Via

… or if the start of header is a case-insensitive match for Proxy- or Sec- (including when header is just Proxy- or Sec-).

The above headers are controlled by the user agent to let it control those aspects of transport. This guarantees data integrity to some extent. Header names starting with Sec- are not allowed to be set to allow new headers to be minted that are guaranteed not to come fromXMLHttpRequest.

4、例子:

testAE.html

 

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$.ajax({     type: "GET",     url: "./testAE.php",     success: function(data) {         $("body").append(data);     },     beforeSend: function(xhr) {         xhr.setRequestHeader("Accept-Encoding", "testAE");     } });

testAE.php

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/*回传ACCEPT_ENCODING*/ echo $_SERVER['HTTP_ACCEPT_ENCODING']; ?>

 

方法二：

 headers: {

             'token':'token_value'

         },