Table of Contents
header函数的作用
HTTP协议的运作方式
HTTP协议状态码表示的意思
操作实例
使用范例
Home php教程 php手册 PHP header()函数的使用

PHP header()函数的使用

Jun 13, 2016 am 09:38 AM
header php

在之前文章中,介绍了 PHP 中 header() 函数的一些情况,这里再补充一下吧。

下面是关于header函数的详细使用说明:

不管页面有多少 header,它会执行最后一个,不过是有条件的,例如:

header('Location:http://www.bkjia.com'); 
header('Location:http://www.g.cn'); 
header('Location:http://www.baidu.com'); 
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这个就会跳到百度

header函数的作用

PHP只是以HTTP协议将HTML文档的标头送到浏览器,告诉浏览器具体怎么处理这个页面,至于传送的内容则需要熟悉一下HTTP协议了,与PHP无关了。

传统的标头一定包含下面三种标头之一,并只能出现一次。

Location: xxxx:yyyy/zzzz 
Content-Type: xxxx/yyyy 
Status: nnn xxxxxx 
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HTTP协议的运作方式

HTTP协议是基于请求/响应范式的。一个客户机与服务器建立连接后,发送一个请求给服务器,请求方式的格式为,统一资源标识符、协议版本号,后边是 MIME信息包括请求修饰符、客户机信息和可能的内容。服务器接到请求后,给予相应的响应信息,其格式为一个状态行包括信息的协议版本号、一个成功或错误的代码,后边是MIME信息包括服务器信息、实体信息和可能的内容。

它分四个过程,在HTTP协议中,服务端是指提供HTTP服务的部分,客户端是指你使用的浏览器或者下载工具等等。在通讯时,由客户端发出请求连接,服务端建立连接;然后,客户端发出HTTP请求(Request),服务端返回响应信息(Respond),由此完成一个HTTP操作。

HTTP协议状态码表示的意思

1××  保留 
2××  表示请求成功地接收 
3××  为完成请求客户需进一步细化请求 
4××  客户错误 
5××  服务器错误   
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操作实例

  • 重定向功能,这种最常见。
  • <?php 
       Header("Location: http://www.php.net/"); 
    ?> 
    
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  • 强制用户每次访问这个页面时获取最新资料,而不是使用存在客户端的缓存。
  • <?php 
    //告诉浏览器此页面的过期时间(用格林威治时间表示),只要是已经过去的日期即可。 
    header("Expires: Mon, 26 Jul 1970 05:00:00 GMT"); 
    //告诉浏览器此页面的最后更新日期(用格林威治时间表示)也就是当天,目的就是强迫浏览器获取最新资料 
    header("Last-Modified: " . gmdate("D, d M Y H:i:s") . "GMT"); 
    //告诉客户端浏览器不使用缓存 
    header("Cache-Control: no-cache, must-revalidate"); 
    //参数(与以前的服务器兼容),即兼容HTTP1.0协议 
    header("Pragma: no-cache"); 
    //输出MIME类型 
    header("Content-type: application/file"); 
    //文件长度 
    header("Content-Length: 227685"); 
    //接受的范围单位 
    header("Accept-Ranges: bytes"); 
    //缺省时文件保存对话框中的文件名称 
    header("Content-Disposition: attachment; filename=$filename"); 
    ?> 
    
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  • 输出状态值到浏览器,主要用于访问权限控制。
  • <?php 
    header('HTTP/1.1 401 Unauthorized'); 
    header('status: 401 Unauthorized'); 
    ?> 
    
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    比如要限制一个用户不能访问该页,则可设置状态为404,如下所示,这样浏览器就显示为即该页不存在 。

    <?php 
    header('HTTP/1.1 404 Not Found'); 
    header("status: 404 Not Found"); 
    ?> 
    
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    注意: 传统的标头一定包含下面三种标头之一,并只能出现一次。 Content-Type: xxxx/yyyy Location: xxxx:yyyy/zzzz Status: nnn xxxxxx 在新的多型标头规格 (Multipart MIME) 方可以出现二次以上。

使用范例

  • 范例一: 本例使浏览器重定向到 PHP 的官方网站。
  • Header("Location: http://www.php.net/"); 
    exit;  
    
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  • 范例二: 要使用者每次都能得到最新的资料,而不是 Proxy 或 cache 中的资料,可以使用下列的标头:
  • header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); 
    header("Last-Modified: " . gmdate("D, d M Y H:i:s") . "GMT"); header("Cache-Control: no-cache, must-revalidate"); 
    header("Pragma: no-cache");  
    
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  • 范例三: 让使用者的浏览器出现找不到档案的信息。
  • header("Status: 404 Not Found"); 
    
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  • 范例四:让使用者下载档案。
  • header("Content-type: application/x-gzip"); 
    header("Content-Disposition: attachment; filename=文件名"); 
    header("Content-Description: PHP3 Generated Data"); 
    
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