Php 简明教程

PHP – JSON

PHP 的标准发行版默认启用 JSON 支持。PHP 扩展实现 JavaScript 对象表示法 (JSON) 数据交换格式。PHP 解析器中的 JSON 扩展处理 JSON 数据。

Standard distributions of PHP have the JSON support enabled by default. The PHP extension implements the JavaScript Object Notation (JSON) data interchange format. The JSON extension in PHP parser handles the JSON data.

JSON（JavaScript 对象表示法）是一种轻量级、基于文本、与语言无关的数据交换格式。JSON 为便携式表示结构化数据定义了一组较小的格式化规则。它是一种基于文本的数据格式，对于人类和机器来说都很容易读取。

JSON (JavaScript Object Notation) is a lightweight, text-based, language-independent data interchange format. JSON defines a small set of formatting rules for the portable representation of structured data. It is a text based data format that is easy for the humans as well as machines to read.

PHP 版本 5.2 及更高版本中的 JSON 扩展提供了许多预定义的常量、JSON 相关函数以及 JsonException 类。

The JSON extension in PHP version 5.2 onwards provides a number of predefined constants, JSON related functions, and also a JsonException class.

PHP JSON Functions

PHP 具有以下 JSON 函数 −

PHP has the following JSON functions −

json_encode()

此函数返回一个字符串，其中包含所提供值的 JSON 表示形式。如果参数是数组或对象，则会递归序列化。

This function returns a string containing the JSON representation of the supplied value. If the parameter is an array or object, it will be serialized recursively.

json_encode(mixed $value, int $flags = 0, int $depth = 512): string|false

json_decode()

此函数采用 JSON 编码的字符串，并将其转换为 PHP 值。

This function takes a JSON encoded string and converts it into a PHP value.

json_decode(
   string $json,
   ?bool $associative = null,
   int $depth = 512,
   int $flags = 0
): mixed

当此函数的关联参数为 true 时，JSON 对象将作为关联数组返回；当为 false 时，JSON 对象将作为对象返回。

When the associative parameter of this function is true, JSON objects will be returned as associative arrays; when false, JSON objects will be returned as objects.

编码/解码操作受所提供标志的影响。预定义常量及其整数值如下 −

The encode/decode operations are affected by the supplied flags. The predefined constants and their integer values are as below −

Predefined Constant

Values

JSON_HEX_TAG

1

JSON_HEX_AMP

2

JSON_HEX_APOS

4

JSON_HEX_QUOT

8

JSON_FORCE_OBJECT

16

JSON_NUMERIC_CHECK

32

JSON_UNESCAPED_SLASHES

64

JSON_PRETTY_PRINT

128

JSON_UNESCAPED_UNICODE

256

json_last_error_msg()

此函数返回最近 json_encode() 或 json_decode() 调用的错误字符串。

This function returns the error string of the last json_encode() or json_decode() call.

json_last_error_msg(): string

如果没有发生错误，则返回“No error”消息。

"No error" message is returned if no error has occurred.

json_last_error()

此函数返回一个整数。

This function returns an integer.

json_last_error(): int

该函数返回一个整数，对应于以下常量之一 −

The function returns an integer corresponding to one of the following constants −

Sr.No

Constant & Meaning

1

JSON_ERROR_NONE No error has occurred

2

JSON_ERROR_DEPTH The maximum stack depth has been exceeded

3

JSON_ERROR_STATE_MISMATCH Invalid or malformed JSON

4

JSON_ERROR_CTRL_CHAR Control character error, possibly incorrectly encoded

5

JSON_ERROR_SYNTAX Syntax error

6

JSON_ERROR_UTF8 Malformed UTF-8 characters, possibly incorrectly encoded

7

JSON_ERROR_RECURSION One or more recursive references in the value to be encoded

8

JSON_ERROR_INF_OR_NAN One or more NAN or INF values in the value to be encoded

9

*JSON_ERROR_UNSUPPORTED_TYPE*A value of a type that cannot be encoded was given

10

JSON_ERROR_INVALID_PROPERTY_NAME A property name that cannot be encoded was given

11

JSON_ERROR_UTF16 Malformed UTF-16 characters, possibly incorrectly encoded

Example

以下 PHP 代码将给定的数组编码为 JSON 表示，并将 JSON 字符串解码回 PHP 数组。

The following PHP code encodes a given array to JSON representation, and decodes the JSON string back to PHP array.

<?php
   $arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
   $encoded = json_encode($arr);
   echo "The initial array: " . PHP_EOL;
   var_dump($arr);
   echo "Encoded JSON: $encoded" . PHP_EOL;

   $decoded = json_decode($encoded);
   echo "Array obtained after decoding: " . PHP_EOL;
   var_dump($decoded);
?>

它将生成以下 output −

It will produce the following output −

The initial array:
array(5) {
   ["a"]=>
   int(1)
   ["b"]=>
   int(2)
   ["c"]=>
   int(3)
   ["d"]=>
   int(4)
   ["e"]=>
   int(5)
}
Encoded JSON: {"a":1,"b":2,"c":3,"d":4,"e":5}
Array obtained after decoding:
object(stdClass)#1 (5) {
   ["a"]=>
   int(1)
   ["b"]=>
   int(2)
   ["c"]=>
   int(3)
   ["d"]=>
   int(4)
   ["e"]=>
   int(5)
}