January 2021
Intermediate to advanced
505 pages
9h 45m
Chinese
Content preview from PHP编程：第4版
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245
第 10 章
图片
网页中显然并不是只有文本，还有
Logo
、按钮、照片、图表、广告和以图标形式出现的图片。
许多用工具（比如
Photoshop
）制作的图片都是静态的、不变的，但也有不少是动态创建的，
比如亚马逊的推荐计划广告中会有包含你名字的股票行情图。
PHP
支持用内建的
GD
扩展库进行图片的绘制。在本章，我们将展示如何用
PHP
来动态
生成图片。
在网页中嵌入图片
认为“文本和图片是混合在一个
HTTP
请求中”是一个常见的误区，这可能是因为，当
你浏览一个页面时，你看到的是混合在一起的单页面。重点要理解的是
：要从网页浏览
器创建一个包含文本和图片的标准网页，需要通过一系列
HTTP
请求来完成，每个请求
都要从网页服务器得到响应，每个响应能且只能包含一种类型的数据，并且每张图片都
需要有一个
HTTP
请求和一个服务端响应。所以当你看到一个页面中包含一些文字和两
张图片时，你要明白它需要耗费三个
HTTP
请求和响应来构建这个页面。
就像下面这个页面
：
<html>
<head>
<title> Example Page </title>
</head>
<body>
这个页面中有两张图片 ：
<img src="image1.png" alt="Image 1" />
<img src="image2.png" alt="Image 2" />
246
｜
第
10
章
图片
</body>
</html>
从网页浏览器发出的一系列请求应像下面这样
：
GET /page.html HTTP/1.0 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.