forked from zyb0408/zyb0408.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy path2018-10-15-浏览器中输入 URL 回车后.html
1291 lines (736 loc) · 46.7 KB
/
2018-10-15-浏览器中输入 URL 回车后.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<html class="theme-next pisces use-motion" lang="zh-Hans">
<head><meta name="generator" content="Hexo 3.8.0">
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<meta name="theme-color" content="#222">
<meta http-equiv="Cache-Control" content="no-transform">
<meta http-equiv="Cache-Control" content="no-siteapp">
<link href="/lib/fancybox/source/jquery.fancybox.css?v=2.1.5" rel="stylesheet" type="text/css">
<link href="/lib/font-awesome/css/font-awesome.min.css?v=4.6.2" rel="stylesheet" type="text/css">
<link href="/css/main.css?v=5.1.4" rel="stylesheet" type="text/css">
<link rel="icon" type="image/png" sizes="32x32" href="/images/favicon-32x32-next.png?v=5.1.4">
<meta name="keywords" content="计算机网络,">
<meta name="description" content="本文摘要：1.DNS域名解析；2.建立TCP连接；3.发送HTTP请求；4.服务器处理请求；5.返回响应结果；6.关闭TCP连接；7.浏览器解析HTML；8.浏览器布局渲染；总结 当我们在浏览器输入网址并回车后，一切从这里开始。 一、DNS域名解析我们在浏览器输入网址，其实就是要向服务器请求我们想要的页面内容，所有浏览器首先要确认的是域名所对应的服务器在哪里。将域名解析成对应的服务器IP地址这项">
<meta name="keywords" content="计算机网络">
<meta property="og:type" content="article">
<meta property="og:title" content="浏览器中输入 URL 回车后...">
<meta property="og:url" content="https://zyb0408.github.io/2018-10-15-浏览器中输入 URL 回车后.html">
<meta property="og:site_name" content="小蜜蜂">
<meta property="og:description" content="本文摘要：1.DNS域名解析；2.建立TCP连接；3.发送HTTP请求；4.服务器处理请求；5.返回响应结果；6.关闭TCP连接；7.浏览器解析HTML；8.浏览器布局渲染；总结 当我们在浏览器输入网址并回车后，一切从这里开始。 一、DNS域名解析我们在浏览器输入网址，其实就是要向服务器请求我们想要的页面内容，所有浏览器首先要确认的是域名所对应的服务器在哪里。将域名解析成对应的服务器IP地址这项">
<meta property="og:locale" content="zh-Hans">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-b099ae26dc79d7b9.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-c164aa67e9dc97ab.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-b926543a4358a161.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-1ac4f67e1f2a2115.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-b5b9faaf6b340a47.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-fc8397e11641afb3.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-a8a24ac0ac40b439.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-e03d70f1e74d6e2b.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-587703c45931be4f.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:image" content="http://upload-images.jianshu.io/upload_images/5996435-d645ffb32ed838c7.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<meta property="og:updated_time" content="2018-10-15T02:09:57.000Z">
<meta name="twitter:card" content="summary">
<meta name="twitter:title" content="浏览器中输入 URL 回车后...">
<meta name="twitter:description" content="本文摘要：1.DNS域名解析；2.建立TCP连接；3.发送HTTP请求；4.服务器处理请求；5.返回响应结果；6.关闭TCP连接；7.浏览器解析HTML；8.浏览器布局渲染；总结 当我们在浏览器输入网址并回车后，一切从这里开始。 一、DNS域名解析我们在浏览器输入网址，其实就是要向服务器请求我们想要的页面内容，所有浏览器首先要确认的是域名所对应的服务器在哪里。将域名解析成对应的服务器IP地址这项">
<meta name="twitter:image" content="http://upload-images.jianshu.io/upload_images/5996435-b099ae26dc79d7b9.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240">
<script type="text/javascript" id="hexo.configurations">
var NexT = window.NexT || {};
var CONFIG = {
root: '/',
scheme: 'Pisces',
version: '5.1.4',
sidebar: {"position":"left","display":"post","offset":12,"b2t":false,"scrollpercent":true,"onmobile":false},
fancybox: true,
tabs: true,
motion: {"enable":true,"async":false,"transition":{"post_block":"fadeIn","post_header":"slideDownIn","post_body":"slideDownIn","coll_header":"slideLeftIn","sidebar":"slideUpIn"}},
duoshuo: {
userId: '0',
author: '博主'
},
algolia: {
applicationID: '',
apiKey: '',
indexName: '',
hits: {"per_page":10},
labels: {"input_placeholder":"Search for Posts","hits_empty":"We didn't find any results for the search: ${query}","hits_stats":"${hits} results found in ${time} ms"}
}
};
</script>
<link rel="canonical" href="https://zyb0408.github.io/2018-10-15-浏览器中输入 URL 回车后.html">
<title>浏览器中输入 URL 回车后... | 小蜜蜂</title>
</head>
<body itemscope="" itemtype="http://schema.org/WebPage" lang="zh-Hans">
<div class="container sidebar-position-left page-post-detail">
<div class="headband"></div>
<header id="header" class="header" itemscope="" itemtype="http://schema.org/WPHeader">
<div class="header-inner"><div class="site-brand-wrapper">
<div class="site-meta custom-logo">
<div class="custom-logo-site-title">
<a href="/" class="brand" rel="start">
<span class="logo-line-before"><i></i></span>
<span class="site-title">小蜜蜂</span>
<span class="logo-line-after"><i></i></span>
</a>
</div>
<p class="site-subtitle">Don't Hack Me</p>
</div>
<div class="site-nav-toggle">
<button>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
<span class="btn-bar"></span>
</button>
</div>
</div>
<nav class="site-nav">
<ul id="menu" class="menu">
<li class="menu-item menu-item-home">
<a href="/" rel="section">
<i class="menu-item-icon fa fa-fw fa-home"></i> <br>
首页
</a>
</li>
<li class="menu-item menu-item-about">
<a href="/about/" rel="section">
<i class="menu-item-icon fa fa-fw fa-user"></i> <br>
关于
</a>
</li>
<li class="menu-item menu-item-tags">
<a href="/tags/" rel="section">
<i class="menu-item-icon fa fa-fw fa-tags"></i> <br>
标签
</a>
</li>
<li class="menu-item menu-item-categories">
<a href="/categories/" rel="section">
<i class="menu-item-icon fa fa-fw fa-th"></i> <br>
分类
</a>
</li>
<li class="menu-item menu-item-archives">
<a href="/archives/" rel="section">
<i class="menu-item-icon fa fa-fw fa-archive"></i> <br>
归档
</a>
</li>
<li class="menu-item menu-item-search">
<a href="javascript:;" class="popup-trigger">
<i class="menu-item-icon fa fa-search fa-fw"></i> <br>
搜索
</a>
</li>
</ul>
<div class="site-search">
<div class="popup search-popup local-search-popup">
<div class="local-search-header clearfix">
<span class="search-icon">
<i class="fa fa-search"></i>
</span>
<span class="popup-btn-close">
<i class="fa fa-times-circle"></i>
</span>
<div class="local-search-input-wrapper">
<input autocomplete="off" placeholder="搜索..." spellcheck="false" type="text" id="local-search-input">
</div>
</div>
<div id="local-search-result"></div>
</div>
</div>
</nav>
</div>
</header>
<main id="main" class="main">
<div class="main-inner">
<div class="content-wrap">
<div id="content" class="content">
<div id="posts" class="posts-expand">
<article class="post post-type-normal" itemscope="" itemtype="http://schema.org/Article">
<div class="post-block">
<link itemprop="mainEntityOfPage" href="https://zyb0408.github.io/2018-10-15-浏览器中输入 URL 回车后.html">
<span hidden itemprop="author" itemscope="" itemtype="http://schema.org/Person">
<meta itemprop="name" content="小蜜蜂">
<meta itemprop="description" content="">
<meta itemprop="image" content="/images/favicon-32x32-next.png">
</span>
<span hidden itemprop="publisher" itemscope="" itemtype="http://schema.org/Organization">
<meta itemprop="name" content="小蜜蜂">
</span>
<header class="post-header">
<h1 class="post-title" itemprop="name headline">浏览器中输入 URL 回车后...</h1>
<div class="post-meta">
<span class="post-time">
<span class="post-meta-item-icon">
<i class="fa fa-calendar-o"></i>
</span>
<span class="post-meta-item-text">发表于</span>
<time title="创建于" itemprop="dateCreated datePublished" datetime="2018-10-15T10:09:57+08:00">
2018-10-15
</time>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-calendar-check-o"></i>
</span>
<span class="post-meta-item-text">更新于:</span>
<time title="更新于" itemprop="dateModified" datetime="2018-10-15T10:09:57+08:00">
2018-10-15
</time>
</span>
<span class="post-category">
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-folder-o"></i>
</span>
<span class="post-meta-item-text">分类于</span>
<span itemprop="about" itemscope="" itemtype="http://schema.org/Thing">
<a href="/categories/计算机网络/" itemprop="url" rel="index">
<span itemprop="name">计算机网络</span>
</a>
</span>
</span>
<span class="post-meta-divider">|</span>
<span class="page-pv"><i class="fa fa-file-o"></i>
<span class="busuanzi-value" id="busuanzi_value_page_pv"></span>
</span>
<div class="post-wordcount">
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-file-word-o"></i>
</span>
<span class="post-meta-item-text">字数统计:</span>
<span title="字数统计">
1.7k
</span>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-clock-o"></i>
</span>
<span class="post-meta-item-text">阅读时长 ≈</span>
<span title="阅读时长">
6
</span>
</div>
</div>
</header>
<div class="post-body" itemprop="articleBody">
<div>
<div>
<div style="text-align:center;color: #636363;font-size:14px;letter-spacing: 10px">���Ľ�����<i class="fa fa-bell"></i>��л�����Ķ�</div>
</div>
</div>
<p>本文摘要：<br>1.DNS域名解析；<br>2.建立TCP连接；<br>3.发送HTTP请求；<br>4.服务器处理请求；<br>5.返回响应结果；<br>6.关闭TCP连接；<br>7.浏览器解析HTML；<br>8.浏览器布局渲染；<br>总结</p>
<p><img src="http://upload-images.jianshu.io/upload_images/5996435-b099ae26dc79d7b9.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 当我们在浏览器输入网址并回车后，一切从这里开始。</p>
<h3 id="一、DNS域名解析"><a href="#一、DNS域名解析" class="headerlink" title="一、DNS域名解析"></a>一、DNS域名解析</h3><p>我们在浏览器输入网址，其实就是要向服务器请求我们想要的页面内容，所有浏览器首先要确认的是域名所对应的服务器在哪里。将域名解析成对应的服务器IP地址这项工作，是由DNS服务器来完成的。 客户端收到你输入的域名地址后，它首先去找本地的hosts文件，检查在该文件中是否有相应的域名、IP对应关系，如果有，则向其IP地址发送请求，如果没有，再去找DNS服务器。一般用户很少去编辑修改hosts文件。 <img src="http://upload-images.jianshu.io/upload_images/5996435-c164aa67e9dc97ab.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> DNS服务器层次结构 <img src="http://upload-images.jianshu.io/upload_images/5996435-b926543a4358a161.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 浏览器客户端向本地DNS服务器发送一个含有域名<a href="http://www.cnblogs.com的DNS查询报文。本地DNS服务器把查询报文转发到根DNS服务器，根DNS服务器注意到其com后缀，于是向本地DNS服务器返回comDNS服务器的IP地址。本地DNS服务器再次向comDNS服务器发送查询请求，comDNS服务器注意到其www.cnblogs.com后缀并用负责该域名的权威DNS服务器的IP地址作为回应。最后，本地DNS服务器将含有www.cnblogs.com的IP地址的响应报文发送给客户端。" target="_blank" rel="noopener">www.cnblogs.com的DNS查询报文。本地DNS服务器把查询报文转发到根DNS服务器，根DNS服务器注意到其com后缀，于是向本地DNS服务器返回comDNS服务器的IP地址。本地DNS服务器再次向comDNS服务器发送查询请求，comDNS服务器注意到其www.cnblogs.com后缀并用负责该域名的权威DNS服务器的IP地址作为回应。最后，本地DNS服务器将含有www.cnblogs.com的IP地址的响应报文发送给客户端。</a></p>
<blockquote>
<p>从客户端到本地服务器属于<strong>递归查询</strong>，而DNS服务器之间的交互属于<strong>迭代查询</strong>。 正常情况下，本地DNS服务器的缓存中已有comDNS服务器的地址，因此请求根域名服务器这一步不是必需的。</p>
</blockquote>
<h3 id="二、建立TCP链接"><a href="#二、建立TCP链接" class="headerlink" title="二、建立TCP链接"></a>二、建立TCP链接</h3><p>费了一顿周折终于拿到服务器IP了，下一步自然就是链接到该服务器。对于客户端与服务器的TCP链接，必然要说的就是『三次握手』。 <img src="http://upload-images.jianshu.io/upload_images/5996435-1ac4f67e1f2a2115.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 三次握手 客户端发送一个带有SYN标志的数据包给服务端，服务端收到后，回传一个带有SYN/ACK标志的数据包以示传达确认信息，最后客户端再回传一个带ACK标志的数据包，代表握手结束，连接成功。 上图也可以这么理解： 客户端：“你好，在家不，有你快递。” 服务端：“在的，送来就行。” 客户端：“好嘞。”</p>
<h3 id="三、发送HTTP请求"><a href="#三、发送HTTP请求" class="headerlink" title="三、发送HTTP请求"></a>三、发送HTTP请求</h3><p>与服务器建立了连接后，就可以向服务器发起请求了。这里我们先看下请求报文的结构（如下图）： <img src="http://upload-images.jianshu.io/upload_images/5996435-b5b9faaf6b340a47.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 请求报文 在浏览器中查看报文首部（以google浏览器为例）： <img src="http://upload-images.jianshu.io/upload_images/5996435-fc8397e11641afb3.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 请求行包括请求方法、URI、HTTP版本。首部字段传递重要信息，包括请求首部字段、通用首部字段和实体首部字段。我们可以从报文中看到发出的请求的具体信息。具体每个首部字段的作用，这里不做过多阐述。</p>
<h3 id="四、服务器处理请求"><a href="#四、服务器处理请求" class="headerlink" title="四、服务器处理请求"></a>四、服务器处理请求</h3><p>服务器端收到请求后的由web服务器（准确说应该是http服务器）处理请求，诸如Apache、Ngnix、IIS等。web服务器解析用户请求，知道了需要调度哪些资源文件，再通过相应的这些资源文件处理用户请求和参数，并调用数据库信息，最后将结果通过web服务器返回给浏览器客户端。 <img src="http://upload-images.jianshu.io/upload_images/5996435-a8a24ac0ac40b439.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 服务器处理请求</p>
<h3 id="五、返回响应结果"><a href="#五、返回响应结果" class="headerlink" title="五、返回响应结果"></a>五、返回响应结果</h3><p>在HTTP里，有请求就会有响应，哪怕是错误信息。这里我们同样看下响应报文的组成结构： <img src="http://upload-images.jianshu.io/upload_images/5996435-e03d70f1e74d6e2b.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 响应报文 在响应结果中都会有个一个HTTP状态码，比如我们熟知的200、301、404、500等。通过这个状态码我们可以知道服务器端的处理是否正常，并能了解具体的错误。 状态码由3位数字和原因短语组成。根据首位数字，状态码可以分为五类： <img src="http://upload-images.jianshu.io/upload_images/5996435-587703c45931be4f.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 状态码类别</p>
<h3 id="六、关闭TCP连接"><a href="#六、关闭TCP连接" class="headerlink" title="六、关闭TCP连接"></a>六、关闭TCP连接</h3><p>为了避免服务器与客户端双方的资源占用和损耗，当双方没有请求或响应传递时，任意一方都可以发起关闭请求。与创建TCP连接的3次握手类似，关闭TCP连接，需要4次握手。 <img src="http://upload-images.jianshu.io/upload_images/5996435-d645ffb32ed838c7.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240" alt=""> 4次握手 上图可以这么理解： 客户端：“兄弟，我这边没数据要传了，咱关闭连接吧。” 服务端：“收到，我看看我这边有木有数据了。” 服务端：“兄弟，我这边也没数据要传你了，咱可以关闭连接了。” 客户端：“好嘞。”</p>
<h3 id="七、浏览器解析HTML"><a href="#七、浏览器解析HTML" class="headerlink" title="七、浏览器解析HTML"></a>七、浏览器解析HTML</h3><p>准确地说，浏览器需要加载解析的不仅仅是HTML，还包括CSS、JS。以及还要加载图片、视频等其他媒体资源。 浏览器通过解析HTML，生成DOM树，解析CSS，生成CSS规则树，然后通过DOM树和CSS规则树生成渲染树。渲染树与DOM树不同，渲染树中并没有head、display为none等不必显示的节点。 要注意的是，浏览器的解析过程并非是串连进行的，比如在解析CSS的同时，可以继续加载解析HTML，但在解析执行JS脚本时，会停止解析后续HTML，这就会出现阻塞问题，关于JS阻塞相关问题，这里不过多阐述,后面会单独开篇讲解。</p>
<h3 id="八、浏览器布局渲染"><a href="#八、浏览器布局渲染" class="headerlink" title="八、浏览器布局渲染"></a>八、浏览器布局渲染</h3><p>根据渲染树布局，计算CSS样式，即每个节点在页面中的大小和位置等几何信息。HTML默认是流式布局的，CSS和js会打破这种布局，改变DOM的外观样式以及大小和位置。这时就要提到两个重要概念：repaint和reflow。</p>
<blockquote>
<p>repaint：屏幕的一部分重画，不影响整体布局，比如某个CSS的背景色变了，但元素的几何尺寸和位置不变。 reflow： 意味着元件的几何尺寸变了，我们需要重新验证并计算渲染树。是渲染树的一部分或全部发生了变化。这就是Reflow，或是Layout。</p>
</blockquote>
<p>所以我们应该尽量减少reflow和repaint，我想这也是为什么现在很少有用table布局的原因之一。 最后浏览器绘制各个节点，将页面展示给用户。</p>
<h3 id="总结"><a href="#总结" class="headerlink" title="总结"></a>总结</h3><p>本文系统地讲述从浏览器从输入域名到最终页面展示的整体流程。篇幅所限，本文的每一步讲述其实并不全面，所以后面我会单独就域名解析、HTTP请求/响应、浏览器的解析、渲染等内容单独开篇讲解。 <a href="http://转载自这里" target="_blank" rel="noopener">http://www.xuecaijie.com/</a></p>
</div>
<div>
<ul class="post-copyright">
<li class="post-copyright-author">
<strong>本文作者：</strong>
小蜜蜂
</li>
<li class="post-copyright-link">
<strong>本文链接：</strong>
<a href="https://zyb0408.github.io/2018-10-15-浏览器中输入 URL 回车后.html" title="浏览器中输入 URL 回车后...">https://zyb0408.github.io/2018-10-15-浏览器中输入 URL 回车后.html</a>
</li>
<li class="post-copyright-license">
<strong>版权声明： </strong>
本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/3.0/" rel="external nofollow" target="_blank">CC BY-NC-SA 3.0</a> 许可协议。转载请注明出处！
</li>
</ul>
</div>
<footer class="post-footer">
<div class="post-tags">
<a href="/tags/计算机网络/" rel="tag"># 计算机网络</a>
</div>
<div class="post-nav">
<div class="post-nav-next post-nav-item">
<a href="/2018-10-15-正规的运维工作是什么的.html" rel="next" title="正规的运维工作是什么的?">
<i class="fa fa-chevron-left"></i> 正规的运维工作是什么的?
</a>
</div>
<span class="post-nav-divider"></span>
<div class="post-nav-prev post-nav-item">
<a href="/2018-10-15-C++函数重载.html" rel="prev" title="C++函数重载">
C++函数重载 <i class="fa fa-chevron-right"></i>
</a>
</div>
</div>
</footer>
</div>
</article>
<div class="post-spread">
</div>
</div>
</div>
</div>
<div class="sidebar-toggle">
<div class="sidebar-toggle-line-wrap">
<span class="sidebar-toggle-line sidebar-toggle-line-first"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-middle"></span>
<span class="sidebar-toggle-line sidebar-toggle-line-last"></span>
</div>
</div>
<aside id="sidebar" class="sidebar">
<div class="sidebar-inner">
<ul class="sidebar-nav motion-element">
<li class="sidebar-nav-toc sidebar-nav-active" data-target="post-toc-wrap">
文章目录
</li>
<li class="sidebar-nav-overview" data-target="site-overview-wrap">
站点概览
</li>
</ul>
<section class="site-overview-wrap sidebar-panel">
<div class="site-overview">
<div class="site-author motion-element" itemprop="author" itemscope="" itemtype="http://schema.org/Person">
<img class="site-author-image" itemprop="image" src="/images/favicon-32x32-next.png" alt="小蜜蜂">
<p class="site-author-name" itemprop="name">小蜜蜂</p>
<p class="site-description motion-element" itemprop="description">小蜜蜂学计算机</p>
</div>
<nav class="site-state motion-element">
<div class="site-state-item site-state-posts">
<a href="/archives/">
<span class="site-state-item-count">52</span>
<span class="site-state-item-name">日志</span>
</a>
</div>
<div class="site-state-item site-state-categories">
<a href="/categories/index.html">
<span class="site-state-item-count">18</span>
<span class="site-state-item-name">分类</span>
</a>
</div>
<div class="site-state-item site-state-tags">
<a href="/tags/index.html">
<span class="site-state-item-count">22</span>
<span class="site-state-item-name">标签</span>
</a>
</div>
</nav>
<div class="links-of-author motion-element">
<span class="links-of-author-item">
<a href="https://github.com/zyb0408" target="_blank" title="GitHub">
<i class="fa fa-fw fa-github"></i>GitHub</a>
</span>
</div>
<div class="links-of-blogroll motion-element links-of-blogroll-block">
<div class="links-of-blogroll-title">
<i class="fa fa-fw fa-link"></i>
Links
</div>
<ul class="links-of-blogroll-list">
<li class="links-of-blogroll-item">
<a href="https://dhupxd.github.io" title="学姐" target="_blank">学姐</a>
</li>
<li class="links-of-blogroll-item">
<a href="https://ztt001.github.io" title="学妹" target="_blank">学妹</a>
</li>
</ul>
</div>
</div>
</section>
<!--noindex-->
<section class="post-toc-wrap motion-element sidebar-panel sidebar-panel-active">
<div class="post-toc">
<div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-3"><a class="nav-link" href="#一、DNS域名解析"><span class="nav-number">1.</span> <span class="nav-text">一、DNS域名解析</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#二、建立TCP链接"><span class="nav-number">2.</span> <span class="nav-text">二、建立TCP链接</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#三、发送HTTP请求"><span class="nav-number">3.</span> <span class="nav-text">三、发送HTTP请求</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#四、服务器处理请求"><span class="nav-number">4.</span> <span class="nav-text">四、服务器处理请求</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#五、返回响应结果"><span class="nav-number">5.</span> <span class="nav-text">五、返回响应结果</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#六、关闭TCP连接"><span class="nav-number">6.</span> <span class="nav-text">六、关闭TCP连接</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#七、浏览器解析HTML"><span class="nav-number">7.</span> <span class="nav-text">七、浏览器解析HTML</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#八、浏览器布局渲染"><span class="nav-number">8.</span> <span class="nav-text">八、浏览器布局渲染</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#总结"><span class="nav-number">9.</span> <span class="nav-text">总结</span></a></li></ol></div>
</div>
</section>
<!--/noindex-->
</div>
</aside>
</div>
</main>
<footer id="footer" class="footer">
<div class="footer-inner">
<script async src="https://dn-lbstatics.qbox.me/busuanzi/2.3/busuanzi.pure.mini.js"></script>
<div class="copyright">© 2017 — <span itemprop="copyrightYear">2019</span>
<span class="with-love">
<i class="fa fa-user"></i>
</span>
<span class="author" itemprop="copyrightHolder">小蜜蜂</span>
<span class="post-meta-divider">|</span>
<span class="post-meta-item-icon">
<i class="fa fa-area-chart"></i>
</span>
<span class="post-meta-item-text">Site words total count:</span>
<span title="Site words total count">88.8k</span>
</div>
<div class="powered-by">
<i class="fa fa-user-md"></i><span id="busuanzi_container_site_uv">
本站访客数:<span id="busuanzi_value_site_uv"></span>
</span>
</div>
<script>
var seconds = 1000;
var minutes = seconds * 60;
var hours = minutes * 60;
var days = hours * 24;
var years = days * 365;
var birthDay = Date.UTC(2017,09,17,00,00,00); // 这里设置建站时间
setInterval(function() {
var today = new Date();
var todayYear = today.getFullYear();
var todayMonth = today.getMonth()+1;
var todayDate = today.getDate();
var todayHour = today.getHours();
var todayMinute = today.getMinutes();
var todaySecond = today.getSeconds();
var now = Date.UTC(todayYear,todayMonth,todayDate,todayHour,todayMinute,todaySecond);
var diff = now - birthDay;
var diffYears = Math.floor(diff/years);
var diffDays = Math.floor((diff/days)-diffYears*365);
var diffHours = Math.floor((diff-(diffYears*365+diffDays)*days)/hours);
var diffMinutes = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours)/minutes);
var diffSeconds = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours-diffMinutes*minutes)/seconds);
document.getElementById('showDays').innerHTML="本站已运行 "+diffYears+" 年 "+diffDays+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒";
}, 1000);
</script>
<script async src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js">
</script>
<div class="busuanzi-count">
<script async src="https://dn-lbstatics.qbox.me/busuanzi/2.3/busuanzi.pure.mini.js"></script>
<span class="site-uv">
<i class="fa fa-user"></i>
<span class="busuanzi-value" id="busuanzi_value_site_uv"></span>
</span>
<span class="site-pv">
<i class="fa fa-eye"></i>
<span class="busuanzi-value" id="busuanzi_value_site_pv"></span>
</span>
</div>
</div>
</footer>
<div class="back-to-top">
<i class="fa fa-arrow-up"></i>
<span id="scrollpercent"><span>0</span>%</span>
</div>
</div>
<script type="text/javascript">
if (Object.prototype.toString.call(window.Promise) !== '[object Function]') {
window.Promise = null;
}
</script>
<script type="text/javascript" src="/lib/jquery/index.js?v=2.1.3"></script>
<script type="text/javascript" src="/lib/fastclick/lib/fastclick.min.js?v=1.0.6"></script>
<script type="text/javascript" src="/lib/jquery_lazyload/jquery.lazyload.js?v=1.9.7"></script>
<script type="text/javascript" src="/lib/velocity/velocity.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/velocity/velocity.ui.min.js?v=1.2.1"></script>
<script type="text/javascript" src="/lib/fancybox/source/jquery.fancybox.pack.js?v=2.1.5"></script>
<script type="text/javascript" src="/lib/canvas-nest/canvas-nest.min.js"></script>
<script type="text/javascript" src="/js/src/utils.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/motion.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/affix.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/schemes/pisces.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/scrollspy.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/post-details.js?v=5.1.4"></script>
<script type="text/javascript" src="/js/src/bootstrap.js?v=5.1.4"></script>
<script type="text/javascript">
// Popup Window;
var isfetched = false;
var isXml = true;
// Search DB path;
var search_path = "search.xml";
if (search_path.length === 0) {
search_path = "search.xml";
} else if (/json$/i.test(search_path)) {
isXml = false;
}
var path = "/" + search_path;
// monitor main search box;
var onPopupClose = function (e) {
$('.popup').hide();
$('#local-search-input').val('');
$('.search-result-list').remove();
$('#no-result').remove();
$(".local-search-pop-overlay").remove();
$('body').css('overflow', '');
}
function proceedsearch() {
$("body")
.append('<div class="search-popup-overlay local-search-pop-overlay"></div>')
.css('overflow', 'hidden');
$('.search-popup-overlay').click(onPopupClose);
$('.popup').toggle();
var $localSearchInput = $('#local-search-input');
$localSearchInput.attr("autocapitalize", "none");
$localSearchInput.attr("autocorrect", "off");
$localSearchInput.focus();
}
// search function;
var searchFunc = function(path, search_id, content_id) {
'use strict';
// start loading animation
$("body")
.append('<div class="search-popup-overlay local-search-pop-overlay">' +
'<div id="search-loading-icon">' +
'<i class="fa fa-spinner fa-pulse fa-5x fa-fw"></i>' +
'</div>' +
'</div>')
.css('overflow', 'hidden');
$("#search-loading-icon").css('margin', '20% auto 0 auto').css('text-align', 'center');
$.ajax({
url: path,
dataType: isXml ? "xml" : "json",
async: true,
success: function(res) {