1. 404： 
    header ("HTTP/1.1 404 Not Found");
  2. 301： 
    header ("HTTP/1.1 301 Moved Permanently"); 
header ("Location:http://www.baidu.com");
  3. 下载文件： 
    header ('Content-type: application/file');
header ("Content-Disposition: attachment; filename='test.file'");
readfile ("test.file");
  4. 允许跨域： 
    header('Access-Control-Allow-Origin:*');
  5. 设置自定义header头： 
    header('Access-Control-Allow-Headers:WWW-Authenticate,Authorization,Set-Cookie,X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version,name');