如何在dart flutter中将json字符串转换为json对象？

您必须使用json.decode。它接受一个json对象，并让您处理嵌套的键值对。我给你写个例子

import 'dart:convert';

// actual data sent is {success: true, data:{token:'token'}}
final response = await client.post(url, body: reqBody);

// Notice how you have to call body from the response if you are using http to retrieve json
final body = json.decode(response.body);

// This is how you get success value out of the actual json
if (body['success']) {
  //Token is nested inside data field so it goes one deeper.
  final String token = body['data']['token'];

  return {"success": true, "token": token};
}