json_decode 在 webservice 调用后返回 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 应用程序调用了一个 php web 服务.Web 服务返回如下所示的 json:

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"}"

现在我喜欢在我的应用程序中解码 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.来自网络服务的响应的 Content-Type:"text/html; charset=utf-8"(也尝试使用 "application/json; charset=utf-8"代码>)

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

刚刚对 OP 提供的字符串进行了一些快速检查.花括号前面的小字符"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.

本质上，您从中获取数据的系统会发送以 UTF-8 编码的数据，并在数据之前添加 BOM.在将字符串放入 json_decode() 之前，您应该从字符串中删除前三个字节(使用 substr($string, 3) 即可).

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

正如 Kuroki Kaze 发现的那样，这个角色肯定是json_decode 失败.其给定形式的字符串不是正确的 JSON 格式结构(请参阅 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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