什么是ETag？ETag作用有哪些_威海佰年网络技术有限公司_网站建设_软件开发_私有云_商标注册_公众号_小程序_APP_物联网_ChatGPT

Categories

Tags

什么是ETag？ETag作用有哪些

ETag是HTTP头的一部分，它是一个字符串标识一个web资源的特定版本。它由web服务器生成，用于标识文件的实体标签。ETag可以用来确定同一资源是否已被修改，这在缓存和验证客户端缓存文件是否过期时很有用。ETag的作用如下： 1.缓存控制：在HTTP响应头部中包含ETag可以帮助浏览器缓存和验证资源。如果资源没有发生任何改变，浏览器可以直接从本地缓存中获取资源，而不需要重新从服务器获取。 2.资源验证：如果浏览器的缓存过期或需要更新，它可以使用请求头中的ETag来验证资源是否已被修改。如果资源没有被修改，服务器可以发送一个响应代码为304的响应，告诉浏览器它可以继续使用缓存中的资源。 3.负载均衡：在使用多个Web服务器负载均衡时，ETag可以确保客户端的请求被重定向到与其之前请求相同的服务器。如果不使用ETag，则可能会发生客户端请求一个资源，但它需要从新的服务器获取，即使其他服务器已经有缓存。

Public @ 2023-06-10 23:50:20

《百度网页搜索质量白皮书》即将上线

发布日期：2014-05-13从5月8日第四届SEO排行榜大会上获悉，百度站长平台即将推出《网页搜索质量白皮书》，百度网页搜索专家王淘在这次大会上将《白皮书》大纲做了重点介绍，引得颇高关注，现将白皮书将呈现的内容提前透露给大家。网页质量关乎着搜索引擎对网站展现的排序，高质量网页会得到尽可能多的展现，而低质量的网页将减少展现机会，甚至不予收录。因而，提升自身的网页质量，对于提升搜索引擎自然排序是重中

Public @ 2021-07-04 16:07:38

【免费送！】超硬核成长秘笈扩容！

还记得我们发布《智能小程序开发者运营技能知识图谱1.0》时开发者们拿到手的雀跃，帮助大家更好地提交资源、顺利接入搜索和Feed。《知识图谱1.0》高清大图的下载次数，竟达到一万多次！受到了大家的广泛好评，正在看本文的你，是不是也曾经下载过呢？近期，不断有开发者来催促我们：我跟着图谱理清了思路，流量比原来几乎翻了三倍！你们啥时候出第二期啊？平台近期更新了不少新功能，新图谱是不是要上线了？你们最近推出

Public @ 2012-06-01 16:02:06

sitemap都支持哪些格式?

支持XML格式和TXT文本格式。

Public @ 2018-09-08 16:11:57

什么是ETag？ETag作用有哪些

ETag是HTTP协议提供的一种用于判断资源是否发生变化的机制。ETag是一个字符串，由服务器生成，在资源被更新时会发生变化。客户端请求资源时，服务器会将资源的ETag值一起返回，客户端可以缓存资源，并记录ETag值。当客户端再次请求该资源时，会将上次记录的ETag值一同发送给服务器。如果此时服务器返回的ETag值与客户端记录的值相同，就说明资源没有变化，客户端可以直接使用缓存的资源，减少网络请求

Public @ 2023-03-25 23:50:19

更多您感兴趣的搜索

基本文件流程错误 SQL 调试

/www/wwwroot/briline.net/public/index.php ( 0.79 KB )
/www/wwwroot/briline.net/public/public.php ( 1.08 KB )
/www/wwwroot/briline.net/thinkphp/start.php ( 0.73 KB )
/www/wwwroot/briline.net/thinkphp/base.php ( 2.66 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Loader.php ( 19.47 KB )
/www/wwwroot/briline.net/vendor/composer/autoload_namespaces.php ( 0.21 KB )
/www/wwwroot/briline.net/vendor/composer/autoload_psr4.php ( 0.84 KB )
/www/wwwroot/briline.net/vendor/composer/autoload_classmap.php ( 0.14 KB )
/www/wwwroot/briline.net/vendor/composer/autoload_files.php ( 0.42 KB )
/www/wwwroot/briline.net/vendor/qiniu/php-sdk/src/Qiniu/functions.php ( 7.10 KB )
/www/wwwroot/briline.net/vendor/qiniu/php-sdk/src/Qiniu/Config.php ( 0.70 KB )
/www/wwwroot/briline.net/vendor/topthink/think-captcha/src/helper.php ( 1.59 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Route.php ( 59.82 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Config.php ( 6.03 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Validate.php ( 40.27 KB )
/www/wwwroot/briline.net/vendor/topthink/think-queue/src/config.php ( 0.77 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Console.php ( 21.22 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Error.php ( 3.59 KB )
/www/wwwroot/briline.net/thinkphp/convention.php ( 10.31 KB )
/www/wwwroot/briline.net/thinkphp/library/think/App.php ( 21.04 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Request.php ( 50.94 KB )
/www/wwwroot/briline.net/app/config.php ( 11.25 KB )
/www/wwwroot/briline.net/app/database.php ( 1.41 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Hook.php ( 4.76 KB )
/www/wwwroot/briline.net/app/tags.php ( 1.16 KB )
/www/wwwroot/briline.net/app/common/behavior/InitBase.php ( 8.17 KB )
/www/wwwroot/briline.net/app/common.php ( 23.29 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Env.php ( 1.25 KB )
/www/wwwroot/briline.net/thinkphp/helper.php ( 17.86 KB )
/www/wwwroot/briline.net/app/function.php ( 0.78 KB )
/www/wwwroot/briline.net/app/extend.php ( 13.29 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Debug.php ( 7.06 KB )
/www/wwwroot/briline.net/app/common/model/Config.php ( 0.78 KB )
/www/wwwroot/briline.net/app/common/model/ModelBase.php ( 12.18 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Model.php ( 66.83 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Db.php ( 6.54 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Log.php ( 5.84 KB )
/www/wwwroot/briline.net/thinkphp/library/think/db/connector/Mysql.php ( 3.94 KB )
/www/wwwroot/briline.net/thinkphp/library/think/db/Connection.php ( 29.97 KB )
/www/wwwroot/briline.net/thinkphp/library/think/db/Query.php ( 86.80 KB )
/www/wwwroot/briline.net/thinkphp/library/think/db/builder/Mysql.php ( 2.16 KB )
/www/wwwroot/briline.net/thinkphp/library/think/db/Builder.php ( 30.47 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Cache.php ( 6.17 KB )
/www/wwwroot/briline.net/thinkphp/library/think/cache/driver/File.php ( 7.46 KB )
/www/wwwroot/briline.net/thinkphp/library/think/cache/Driver.php ( 5.52 KB )
/www/wwwroot/briline.net/app/common/behavior/InitHook.php ( 1.25 KB )
/www/wwwroot/briline.net/app/common/model/Hook.php ( 0.77 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Lang.php ( 6.95 KB )
/www/wwwroot/briline.net/thinkphp/lang/zh-cn.php ( 3.85 KB )
/www/wwwroot/briline.net/app/route.php ( 0.91 KB )
/www/wwwroot/briline.net/app/index/config.php ( 0.96 KB )
/www/wwwroot/briline.net/app/index/common.php ( 0.68 KB )
/www/wwwroot/briline.net/app/index/controller/Wiki.php ( 2.44 KB )
/www/wwwroot/briline.net/app/index/controller/IndexBase.php ( 1.10 KB )
/www/wwwroot/briline.net/app/common/controller/ControllerBase.php ( 4.75 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Controller.php ( 6.20 KB )
/www/wwwroot/briline.net/thinkphp/library/traits/controller/Jump.php ( 4.97 KB )
/www/wwwroot/briline.net/thinkphp/library/think/View.php ( 6.86 KB )
/www/wwwroot/briline.net/thinkphp/library/think/view/driver/Think.php ( 5.61 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Template.php ( 46.46 KB )
/www/wwwroot/briline.net/thinkphp/library/think/template/driver/File.php ( 2.24 KB )
/www/wwwroot/briline.net/app/index/logic/Wiki.php ( 6.16 KB )
/www/wwwroot/briline.net/app/index/logic/IndexBase.php ( 0.79 KB )
/www/wwwroot/briline.net/app/common/logic/LogicBase.php ( 0.83 KB )
/www/wwwroot/briline.net/app/common/model/Article.php ( 0.78 KB )
/www/wwwroot/briline.net/app/common/model/ArticleTongji.php ( 0.79 KB )
/www/wwwroot/briline.net/thinkphp/library/think/paginator/driver/Bootstrap.php ( 5.90 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Paginator.php ( 9.45 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Collection.php ( 8.63 KB )
/www/wwwroot/briline.net/runtime/temp/ead4923c25a6b3f986358f7070f93dfa.php ( 56.51 KB )
/www/wwwroot/briline.net/thinkphp/library/think/Response.php ( 8.64 KB )
/www/wwwroot/briline.net/thinkphp/library/think/debug/Html.php ( 4.27 KB )

[ DB ] CONNECT:[ UseTime:0.021809s ] mysql:dbname=briline.net;host=106.14.77.182;port=3306;charset=utf8
[ SQL ] SHOW COLUMNS FROM `ob_article` [ RunTime:0.015397s ]
[ SQL ] SELECT * FROM `ob_article` WHERE `id` = 8735 LIMIT 1 [ RunTime:0.014333s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'const', 'possible_keys' => 'PRIMARY', 'key' => 'PRIMARY', 'key_len' => '4', 'ref' => 'const', 'rows' => 1, 'extra' => NULL, ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='cate' order by times desc limit 15 [ RunTime:0.014509s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using filesort', ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='tags' order by times desc limit 100 [ RunTime:0.014751s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using filesort', ) ]
[ SQL ] select * from `ob_article_tongji` where category_id=12 and mark_type='tags' order by rand() limit 30 [ RunTime:0.015093s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article_tongji', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 608, 'extra' => 'Using where; Using temporary; Using filesort', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `id` = 8735 LIMIT 1 [ RunTime:0.014276s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'const', 'possible_keys' => 'PRIMARY', 'key' => 'PRIMARY', 'key_len' => '4', 'ref' => 'const', 'rows' => 1, 'extra' => NULL, ) ]
[ SQL ] update `ob_article` set views=views+1 where id=8735 [ RunTime:0.017970s ]
[ SQL ] SELECT COUNT(*) AS tp_count FROM `ob_article` WHERE `category_id` = 12 AND `cate` = '威海百度搜索资源平台' AND `status` <> -1 LIMIT 1 [ RunTime:0.022373s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 8035, 'extra' => 'Using where', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `category_id` = 12 AND `cate` = '威海百度搜索资源平台' AND `status` <> -1 ORDER BY rand() LIMIT 0,2 [ RunTime:0.042026s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 8035, 'extra' => 'Using where; Using temporary; Using filesort', ) ]
[ SQL ] SELECT COUNT(*) AS tp_count FROM `ob_article` WHERE `category_id` = 12 AND `tags` = '威海Sitemap' AND `status` <> -1 LIMIT 1 [ RunTime:0.021897s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 8035, 'extra' => 'Using where', ) ]
[ SQL ] SELECT * FROM `ob_article` WHERE `category_id` = 12 AND `tags` = '威海Sitemap' AND `status` <> -1 ORDER BY rand() LIMIT 0,2 [ RunTime:0.036329s ]
[ EXPLAIN : array ( 'id' => 1, 'select_type' => 'SIMPLE', 'table' => 'ob_article', 'type' => 'ALL', 'possible_keys' => NULL, 'key' => NULL, 'key_len' => NULL, 'ref' => NULL, 'rows' => 8035, 'extra' => 'Using where; Using temporary; Using filesort', ) ]

0.418753s

ShowPageTrace