php中json
一、json_encode() 该函数主要用来将数组和对象，转换为json式。先看一个数组转换的例子： $arr = array ( 'a' = 1 , 'b' = 2 , 'c' = 3 , 'd' = 4 , 'e' = 5 ) ; echo json_encode ( $arr ) ; 结果为 { a : 1 , b : 2 , c : 3 , d : 4 , e : 5 } 再看一个对
一、json_encode()
该函数主要用来将数组和对象，转换为json格式。先看一个数组转换的例子：
<code> <span>$arr</span> <span>=</span> <span>array</span> <span>(</span><span>'a'</span><span>=</span><span>></span><span>1</span><span>,</span><span>'b'</span><span>=</span><span>></span><span>2</span><span>,</span><span>'c'</span><span>=</span><span>></span><span>3</span><span>,</span><span>'d'</span><span>=</span><span>></span><span>4</span><span>,</span><span>'e'</span><span>=</span><span>></span><span>5</span><span>)</span><span>;</span> <span>echo</span> <span>json_encode<span>(</span></span><span>$arr</span><span>)</span><span>;</span> </code>Copy after login
结果为
<code> <span>{</span><span>"a"</span><span>:</span><span>1</span><span>,</span><span>"b"</span><span>:</span><span>2</span><span>,</span><span>"c"</span><span>:</span><span>3</span><span>,</span><span>"d"</span><span>:</span><span>4</span><span>,</span><span>"e"</span><span>:</span><span>5</span><span>}</span> </code>Copy after login
再看一个对象转换的例子：
<code> <span>$obj</span><span>-</span><span>></span><span>body</span> <span>=</span> <span>'another post'</span><span>;</span> <span>$obj</span><span>-</span><span>></span><span>id</span> <span>=</span> <span>21</span><span>;</span> <span>$obj</span><span>-</span><span>></span><span>approved</span> <span>=</span> <span>true</span><span>;</span> <span>$obj</span><span>-</span><span>></span><span>favorite_count</span> <span>=</span> <span>1</span><span>;</span> <span>$obj</span><span>-</span><span>></span><span>status</span> <span>=</span> <span>NULL</span><span>;</span> <span>echo</span> <span>json_encode<span>(</span></span><span>$obj</span><span>)</span><span>;</span> </code>Copy after login
结果为
<code> <span>{</span> <span>"body"</span><span>:</span><span>"another post"</span><span>,</span> <span>"id"</span><span>:</span><span>21</span><span>,</span> <span>"approved"</span><span>:</span><span>true</span><span>,</span> <span>"favorite_count"</span><span>:</span><span>1</span><span>,</span> <span>"status"</span><span>:</span><span>null</span> <span>}</span> </code>Copy after login
由于json只接受utf-8编码的字符，所以json_encode()的参数必须是utf-8编码，否则会得到空字符或者null。当中文使用GB2312编码，或者外文使用ISO-8859-1编码的时候，这一点要特别注意。
二、索引数组和关联数组
PHP支持两种数组，一种是只保存"值"（value）的索引数组（indexed array），另一种是保存"名值对"（name/value）的关联数组（associative array）。
由于javascript不支持关联数组，所以json_encode()只将索引数组（indexed array）转为数组格式，而将关联数组（associative array）转为对象格式。
比如，现在有一个索引数组
<code> <span>$arr</span> <span>=</span> <span>Array</span><span>(</span><span>'one'</span><span>,</span> <span>'two'</span><span>,</span> <span>'three'</span><span>)</span><span>;</span> <span>echo</span> <span>json_encode<span>(</span></span><span>$arr</span><span>)</span><span>;</span> </code>Copy after login
结果为：
<code> <span>[</span><span>"one"</span><span>,</span><span>"two"</span><span>,</span><span>"three"</span><span>]</span> </code>Copy after login
如果将它改为关联数组：
<code> <span>$arr</span> <span>=</span> <span>Array</span><span>(</span><span>'1'</span><span>=</span><span>></span><span>'one'</span><span>,</span> <span>'2'</span><span>=</span><span>></span><span>'two'</span><span>,</span> <span>'3'</span><span>=</span><span>></span><span>'three'</span><span>)</span><span>;</span> <span>echo</span> <span>json_encode<span>(</span></span><span>$arr</span><span>)</span><span>;</span> </code>Copy after login
结果就变了：
<code> <span>{</span><span>"1"</span><span>:</span><span>"one"</span><span>,</span><span>"2"</span><span>:</span><span>"two"</span><span>,</span><span>"3"</span><span>:</span><span>"three"</span><span>}</span> </code>Copy after login
注意，数据格式从"[]"（数组）变成了"{}"（对象）。
如果你需要将"索引数组"强制转化成"对象"，可以这样写
<code> <span>json_encode<span>(</span></span> <span>(</span>object<span>)</span><span>$arr</span> <span>)</span><span>;</span> </code>Copy after login
或者
<code> json_encode <span>(</span> <span>$arr</span><span>,</span> <span>JSON_FORCE_OBJECT</span> <span>)</span><span>;</span> </code>Copy after login
三、类（class）的转换
下面是一个PHP的类：
<code> <span>class</span> <span>Foo</span> <span>{</span> <span>const</span> <span>ERROR_CODE</span> <span>=</span> <span>'404'</span><span>;</span> <span>public</span> <span>$public_ex</span> <span>=</span> <span>'this is public'</span><span>;</span> <span>private</span> <span>$private_ex</span> <span>=</span> <span>'this is private!'</span><span>;</span> <span>protected</span> <span>$protected_ex</span> <span>=</span> <span>'this should be protected'</span><span>;</span> <span>public</span> <span>function</span> <span>getErrorCode<span>(</span></span><span>)</span> <span>{</span> <span>return</span> self<span>:</span><span>:</span><span>ERROR_CODE</span><span>;</span> <span>}</span> <span>}</span> </code>Copy after login
现在，对这个类的实例进行json转换：
<code> <span>$foo</span> <span>=</span> <span>new</span> <span>Foo</span><span>;</span> <span>$foo_json</span> <span>=</span> <span>json_encode<span>(</span></span><span>$foo</span><span>)</span><span>;</span> <span>echo</span> <span>$foo_json</span><span>;</span> </code>Copy after login
输出结果是
<code> <span>{</span><span>"public_ex"</span><span>:</span><span>"this is public"</span><span>}</span> </code>Copy after login
可以看到，除了公开变量（public），其他东西（常量、私有变量、方法等等）都遗失了。
四、json_decode()
该函数用于将json文本转换为相应的PHP数据结构。下面是一个例子：
<code> <span>$json</span> <span>=</span> <span>'{"foo": 12345}'</span><span>;</span> <span>$obj</span> <span>=</span> <span>json_decode<span>(</span></span><span>$json</span><span>)</span><span>;</span> <span>print</span> <span>$obj</span><span>-</span><span>></span><span>{</span><span>'foo'</span><span>}</span><span>;</span><span> // 12345 </span> </code>Copy after login
通常情况下，json_decode()总是返回一个PHP对象，而不是数组。比如：
<code> <span>$json</span> <span>=</span> <span>'{"a":1,"b":2,"c":3,"d":4,"e":5}'</span><span>;</span> <span>var_dump<span>(</span></span><span>json_decode<span>(</span></span><span>$json</span><span>)</span><span>)</span><span>;</span> </code>Copy after login
结果就是生成一个PHP对象：
<code> <span>object<span>(</span></span>stdClass<span>)</span>#<span>1</span> <span>(</span><span>5</span><span>)</span> <span>{</span> <span>[</span><span>"a"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>1</span><span>)</span> <span>[</span><span>"b"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>2</span><span>)</span> <span>[</span><span>"c"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>3</span><span>)</span> <span>[</span><span>"d"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>4</span><span>)</span> <span>[</span><span>"e"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>5</span><span>)</span> <span>}</span> </code>Copy after login
如果想要强制生成PHP关联数组，json_decode()需要加一个参数true：
<code> <span>$json</span> <span>=</span> <span>'{"a":1,"b":2,"c":3,"d":4,"e":5}'</span><span>;</span> <span>var_dump<span>(</span></span><span>json_decode<span>(</span></span><span>$json</span><span>,</span><span>true</span><span>)</span><span>)</span><span>;</span> </code>Copy after login
结果就生成了一个关联数组：
<code> <span>array</span><span>(</span><span>5</span><span>)</span> <span>{</span> <span>[</span><span>"a"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>1</span><span>)</span> <span>[</span><span>"b"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>2</span><span>)</span> <span>[</span><span>"c"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>3</span><span>)</span> <span>[</span><span>"d"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>4</span><span>)</span> <span>[</span><span>"e"</span><span>]</span> <span>=</span><span>></span> <span>int<span>(</span></span><span>5</span><span>)</span> <span>}</span> </code>Copy after login
五、json_decode()的常见错误
下面三种json写法都是错的，你能看出错在哪里吗？
<code> <span>$bad_json</span> <span>=</span> <span>"{ 'bar': 'baz' }"</span><span>;</span> <span>$bad_json</span> <span>=</span> <span>'{ bar: "baz" }'</span><span>;</span> <span>$bad_json</span> <span>=</span> <span>'{ "bar": "baz", }'</span><span>;</span> </code>Copy after login
对这三个字符串执行json_decode()都将返回null，并且报错。
第一个的错误是，json的分隔符（delimiter）只允许使用双引号，不能使用单引号。第二个的错误是，json名值对的"名"（冒号左边的部分），任何情况下都必须使用双引号。第三个的错误是，最后一个值之后不能添加逗号（trailing comma）。
另外，json只能用来表示对象（object）和数组（array），如果对一个字符串或数值使用json_decode()，将会返回null。
<code> <span>var_dump<span>(</span></span><span>json_decode<span>(</span></span><span>"Hello World"</span><span>)</span><span>)</span><span>;</span><span> //null</span></code>Copy after login
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
CakePHP Project Configuration
Sep 10, 2024 pm 05:25 PM
In this chapter, we will understand the Environment Variables, General Configuration, Database Configuration and Email Configuration in CakePHP.
PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian
Dec 24, 2024 pm 04:42 PM
PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati
CakePHP Date and Time
Sep 10, 2024 pm 05:27 PM
To work with date and time in cakephp4, we are going to make use of the available FrozenTime class.
CakePHP File upload
Sep 10, 2024 pm 05:27 PM
To work on file upload we are going to use the form helper. Here, is an example for file upload.
CakePHP Routing
Sep 10, 2024 pm 05:25 PM
In this chapter, we are going to learn the following topics related to routing ?
Discuss CakePHP
Sep 10, 2024 pm 05:28 PM
CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on a MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers gu
CakePHP Creating Validators
Sep 10, 2024 pm 05:26 PM
Validator can be created by adding the following two lines in the controller.
How To Set Up Visual Studio Code (VS Code) for PHP Development
Dec 20, 2024 am 11:31 AM
Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c
