The definition and usage of PHP header

<?php
header(&#39;HTTP/1.1 200 OK&#39;); // ok 正常访问
header(&#39;HTTP/1.1 404 Not Found&#39;); //通知浏览器 页面不存在
header(&#39;HTTP/1.1 301 Moved Permanently&#39;); //设置地址被永久的重定向 301
header(&#39;Location: http://www.ithhc.cn/&#39;); //跳转到一个新的地址
header(&#39;Refresh: 10; url=http://www.ithhc.cn/&#39;); //延迟转向 也就是隔几秒跳转
header(&#39;X-Powered-By: PHP/6.0.0&#39;); //修改 X-Powered-By信息
header(&#39;Content-language: en&#39;); //文档语言
header(&#39;Content-Length: 1234&#39;); //设置内容长度
header(&#39;Last-Modified: &#39;.gmdate(&#39;D, d M Y H:i:s&#39;, $time).&#39; GMT&#39;); //告诉浏览器最后一次修改时间
header(&#39;HTTP/1.1 304 Not Modified&#39;); //告诉浏览器文档内容没有发生改变
 
###内容类型###
header(&#39;Content-Type: text/html; charset=utf-8&#39;); //网页编码
header(&#39;Content-Type: text/plain&#39;); //纯文本格式
header(&#39;Content-Type: image/jpeg&#39;); //JPG、JPEG 
header(&#39;Content-Type: application/zip&#39;); // ZIP文件
header(&#39;Content-Type: application/pdf&#39;); // PDF文件
header(&#39;Content-Type: audio/mpeg&#39;); // 音频文件 
header(&#39;Content-type: text/css&#39;); //css文件
header(&#39;Content-type: text/javascript&#39;); //js文件
header(&#39;Content-type: application/json&#39;); //json
header(&#39;Content-type: application/pdf&#39;); //pdf
header(&#39;Content-type: text/xml&#39;); //xml
header(&#39;Content-Type: application/x-shockw**e-flash&#39;); //Flash动画
 
######
 
###声明一个下载的文件###
header(&#39;Content-Type: application/octet-stream&#39;);
header(&#39;Content-Disposition: attachment; filename="ITblog.zip"&#39;);
header(&#39;Content-Transfer-Encoding: binary&#39;);
readfile(&#39;test.zip&#39;);
######
 
###对当前文档禁用缓存###
header(&#39;Cache-Control: no-cache, no-store, max-age=0, must-revalidate&#39;);
header(&#39;Expires: Mon, 26 Jul 1997 05:00:00 GMT&#39;);
######
 
###显示一个需要验证的登陆对话框### 
header(&#39;HTTP/1.1 401 Unauthorized&#39;); 
header(&#39;WWW-Authenticate: Basic realm="Top Secret"&#39;); 
######
 
 
###声明一个需要下载的xls文件###
header(&#39;Content-Disposition: attachment; filename=ithhc.xlsx&#39;);
header(&#39;Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet&#39;);
header(&#39;Content-Length: &#39;.filesize(&#39;./test.xls&#39;)); 
header(&#39;Content-Transfer-Encoding: binary&#39;); 
header(&#39;Cache-Control: must-revalidate&#39;); 
header(&#39;Pragma: public&#39;); 
readfile(&#39;./test.xls&#39;); 
######
?>