Home php教程 PHP开发 Some notes on the json_encode() and json_decode() functions in php

Some notes on the json_encode() and json_decode() functions in php

Dec 12, 2016 am 09:34 AM
php

一,json语法( php中的json_decode($json)中的$json要符合json语法格式 )

① JSON可以表示三种类型的值

1,简单值。包括整型,字符串型,布尔值和null。例如:5,"hello world",true,null都是有效的JSON数据。其中JSON字符串必须使用双引号(单引号会导致语法错误)。

2,对象。如,{"name":"tony","age":15}。说明①要求属性必须用双引号(不加或者单引号都是错误的)②值可以是简单值(注意若值为字符串,必须用双引号,不能用单引号),也可以是复杂类型的值(对象或数组)。

3,数组。如,[25,true,"tony"]。说明:数组的值也可以是任意类型。

二,php定义对象字面量时,不支持直接书写,如{"a":"11","b":"22"}。这种书写方式在其他语言中被支持,在php中需要按如下方式定义:

①  $a = '{"a":"11","b":"22"}' ;【这是json字符串,不加外面的单引号则是json对象】

②  $b = json_decode($a);

这样$b就是对象字面量了。

三,上述三种数值类型经过json_encode($value)转化后,会输出json格式(此时类型为字符串),如"hello",{},[]。输出的结果可以在其他地方(javascrip,ios,java,php等等)被解析使用。

四,php中改进后的json_encode()和json_decode()函数,支持汉语(原生的不支持汉语)

注:php中不可直接改写原生函数,需要写在类里,作为类的一个方法

static function json_encode($input)
{
// 从 PHP 5.4.0 起, 增加了这个选项.
if (defined('JSON_UNESCAPED_UNICODE')) {
return json_encode($input, JSON_UNESCAPED_UNICODE);
}
 
if (is_string($input)) {
$text = $input;
$text = str_replace('\\', '\\\\', $text);
$text = str_replace(
array("\r", "\n", "\t", "\""),
array('\r', '\n', '\t', '\\"'),
$text);
return '"' . $text . '"';
} else if (is_array($input) || is_object($input)) {
$arr = array();
$is_obj = is_object($input) || (array_keys($input) !== range(0, count($input) - 1));
foreach ($input as $k => $v) {
if($v == null){
$v = 'null';
}
if ($is_obj) {
$arr[] = self::json_encode($k) . ':' . self::json_encode($v);
} else {
$arr[] = self::json_encode($v);
}
}
 
if ($is_obj) {
return '{' . join(',', $arr) . '}';
} else {
return '[' . join(',', $arr) . ']';
}
} else {
return $input . '';
}
}
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