调用webservice后json_decode返回NULL [英] json_decode returns NULL after webservice call

问题描述

json_encode和json_decode有一个奇怪的行为，我找不到解决方案:

There is a strange behaviour with json_encode and json_decode and I can't find a solution:

我的php应用程序调用了php Web服务. Web服务返回的json如下所示:

My php application calls a php web service. The webservice returns json that looks like this:

var_dump($foo):
string(62) "{"action":"set","user":"123123123123","status":"OK"}"

现在我想在应用程序中解码json:

now I like to decode the json in my application:

$data = json_decode($foo, true)

，但它返回NULL:

var_dump($data):
NULL

我使用php5. 来自Web服务的响应的Content-Type:"text/html; charset=utf-8"(也尝试使用"application/json; charset=utf-8")

I use php5. The Content-Type of the response from the webservice: "text/html; charset=utf-8" (also tried to use "application/json; charset=utf-8")

可能是什么原因?

推荐答案

只是对OP提供的字符串做了一些快速检查.花括号前的小字符"是 UTF-8 B(yte)O(rder )M(ark) 0xEF 0xBB 0xBF.我不知道为什么这个字节序列在这里显示为.

Just did some quick inspection of the string provided by the OP. The small "character" in front of the curly brace is a UTF-8 B(yte) O(rder) M(ark) 0xEF 0xBB 0xBF. I don't know why this byte sequence is displayed as  here.

从本质上来说，您是从中获取数据的系统发送以UTF-8编码的数据，并在数据之前添加了BOM.您应该先将字符串的前三个字节删除，然后再将其放入json_decode()(substr($string, 3)可以).

Essentially the system you aquire the data from sends it encoded in UTF-8 with a BOM preceding the data. You should remove the first three bytes from the string before you throw it into json_decode() (a substr($string, 3) will do).

string(62) "{"action":"set","user":"123123123123","status":"OK"}"
            ^
            |
            This is the UTF-8 BOM

Kuroki Kaze 被发现，此字符肯定是json_decode失败.给定格式的字符串不是JSON格式的正确结构(请参见 RFC 4627 )

As Kuroki Kaze discovered, this character surely is the reason why json_decode fails. The string in its given form is not correctly a JSON formated structure (see RFC 4627)

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