我们知道，某些情况下由于网站迁移，权限，页面错误时我们可能需要跳转页面到错误页面，如
1.HTTP/1.1 404 Not Found
2.HTTP/1.1 301 Moved Permanently
3.HTTP/1.1 302 Moved Temporarily
但是我们发送响应码只是一种状态机制，因此往往我们需要选择合适的跳转方式，Location跳转是一种常见的方式，特别对于做SEO的同学来说
下面我们通过php语言来说明（结果与编程语言无关）
index.php
<?php
header('HTTP/1.1 301 Moved Permanently');
Header( "Location: http://192.168.1.98/result.php?".$_SERVER['QUERY_STRING'] );
exit();result.php
<?php
$arr = [];
$arr['name'] = 'zhangsan';
$arr['age'] = 20;
echo json_encode($arr);
?>当我们访问http://192.168.1.98/index.php?st=123ABC时，发生了如下转换
Request-1
GET /test/ HTTP/1.1
Host: localhost
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.157 Safari/537.36
Content-Type: text/plain; charset=utf-8
Accept: */*
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8,en;q=0.6RedirectTo
HTTP/1.1 301 Moved Permanently
Date: Sun, 30 Aug 2015 09:59:14 GMT
Server: Apache/2.4.9 (Win32) PHP/5.5.12
X-Powered-By: PHP/5.5.12
Location: http://localhost/test/result.php
Content-Length: 0
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/htmlRequest-2
GET /test/ HTTP/1.1
Host: localhost
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.157 Safari/537.36
Content-Type: text/plain; charset=utf-8
Accept: */*
Accept-Encoding: gzip, deflate, sdch
Accept-Language: zh-CN,zh;q=0.8,en;q=0.6responseTo
HTTP/1.1 200 OK
Date: Sun, 30 Aug 2015 09:59:14 GMT
Server: Apache/2.4.9 (Win32) PHP/5.5.12
X-Powered-By: PHP/5.5.12
Content-Length: 28
Keep-Alive: timeout=5, max=99
Connection: Keep-Alive
Content-Type: text/html响应体
{"name":"zhangsan","age":20}总结：
在这个过程中Request-1与Request-2相同，也就是说Location在跳转的时候同样将请求进行了转发，在这一过程中，一个请求被传递了2次，跳转的过程中并未改变客户端连接，只是服务器端进行了跳转，整个过程是完整的，所以Location使得http请求过程具有完整性和连续性
使用方向：
1.SEO优化，固定重定向
2.请求转发跳转
3.权限检测，拦截，重要文件下载（先判断权限，然后跳转到文件链接，类似某视频网站的）
