Unity C#如何使用Json Utility读取HTTP服务器的JSON数据

Hey there! Let's walk through this step by step—since you're new to Unity's JsonUtility, it's totally normal to get stuck on matching JSON structures to C# classes. Let's fix your parsing issue and get you access to that stock data.

Step 1: Create Serializable C# Classes Matching the JSON Structure #

First, we need to define C# classes that exactly mirror the JSON response from the IEX API. Every class used for parsing must have the [Serializable] attribute—this tells Unity's JsonUtility that it can work with the class.

Root Stock Data Class #

The top-level JSON has three keys: quote, news, and chart. We'll create a root class to hold all three:

using System.Collections.Generic;
using UnityEngine;

[Serializable]
public class StockData
{
    public Quote quote;
    public List<NewsItem> news;
    public List<ChartData> chart;
}

Quote Class (Matches the quote JSON Object) #

This class maps directly to the quote data you shared in your example:

[Serializable]
public class Quote
{
    public string symbol;
    public string companyName;
    public string primaryExchange;
    public string sector;
    public string calculationPrice;
    public float open;
    public long openTime;
    public float close;
    public long closeTime;
    public float high;
    public float low;
    public float latestPrice;
    public string latestSource;
    public string latestTime;
    public long latestUpdate;
    public long latestVolume;
    public float iexRealtimePrice;
    public int iexRealtimeSize;
    public long iexLastUpdated;
    public float delayedPrice;
    public long delayedPriceTime;
    public float previousClose;
    public float change;
    public float changePercent;
    public float iexMarketPercent;
    public long iexVolume;
    public long avgTotalVolume;
    public float iexBidPrice;
    public int iexBidSize;
    public float iexAskPrice;
    public int iexAskSize;
    public long marketCap;
    public float peRatio;
    public float week52High;
    public float week52Low;
    public float ytdChange;
}

News Item Class (Matches news Array Entries) #

The API returns a list of news items—here's a class to match those:

[Serializable]
public class NewsItem
{
    public string datetime;
    public string headline;
    public string source;
    public string url;
    public string summary;
    public string related;
    public string image;
    public string lang;
    public bool hasPaywall;
}

Chart Data Class (Matches chart Array Entries) #

For the 1-month chart data, use this class:

[Serializable]
public class ChartData
{
    public string date;
    public float open;
    public float high;
    public float low;
    public float close;
    public long volume;
    public float uOpen;
    public float uHigh;
    public float uLow;
    public float uClose;
    public long uVolume;
    public float change;
    public float changePercent;
    public float vwap;
    public string label;
    public float changeOverTime;
}

Step 2: Update Your DataManager to Parse the JSON #

Now let's modify your existing DataManager script to actually parse the JSON string into usable C# objects. We'll also fix a small inefficiency in how you set the URL.

Updated DataManager Code #

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DataManager : MonoBehaviour
{
    public string Index_name;
    public string jsonString;

    // Remove the URL assignment from Update—no need to set it every frame!
    // void Update() { ... }

    public void Text_Changed(string newIndex)
    {
        Index_name = newIndex;
    }

    public void Request()
    {
        // Build the URL only when we need to make a request
        string requestUrl = $"https://api.iextrading.com/1.0/stock/{Index_name}/batch?types=quote,news,chart&range=1m&last=10";
        WWW request = new WWW(requestUrl);
        StartCoroutine(OnResponse(request));
    }

    private IEnumerator OnResponse(WWW req)
    {
        yield return req;

        // Check for request errors first
        if (!string.IsNullOrEmpty(req.error))
        {
            Debug.LogError($"Request failed: {req.error}");
            return;
        }

        jsonString = req.text;

        // Parse the JSON into our StockData object
        StockData stockData = JsonUtility.FromJson<StockData>(jsonString);

        // Test if parsing worked by logging some data
        if (stockData != null && stockData.quote != null)
        {
            Debug.Log($"Symbol: {stockData.quote.symbol}");
            Debug.Log($"Latest Price: ${stockData.quote.latestPrice}");
            Debug.Log($"Company: {stockData.quote.companyName}");
        }

        // Log a sample news item if available
        if (stockData.news != null && stockData.news.Count > 0)
        {
            Debug.Log($"Top News: {stockData.news[0].headline}");
        }
    }
}

Key Tips to Remember #

• Case Sensitivity: C# field names must exactly match the JSON keys (e.g., companyName in JSON = companyName in C#—not CompanyName).
• Serializable Attribute: Don't forget [Serializable] on every class used for parsing—JsonUtility ignores classes without it.
• Arrays/Lists: JSON arrays (like news and chart) map to C# List<T> or T[] arrays—both work with JsonUtility.
• WWW is Deprecated: For newer Unity versions, use UnityWebRequest instead of WWW (it's more secure and efficient). Here's a quick replacement for the Request method:

  public void RequestWithUnityWebRequest()
  {
      string requestUrl = $"https://api.iextrading.com/1.0/stock/{Index_name}/batch?types=quote,news,chart&range=1m&last=10";
      StartCoroutine(SendUnityWebRequest(requestUrl));
  }
  
  private IEnumerator SendUnityWebRequest(string url)
  {
      using (UnityWebRequest webRequest = UnityWebRequest.Get(url))
      {
          yield return webRequest.SendWebRequest();
  
          if (webRequest.result != UnityWebRequest.Result.Success)
          {
              Debug.LogError($"Request failed: {webRequest.error}");
          }
          else
          {
              jsonString = webRequest.downloadHandler.text;
              StockData stockData = JsonUtility.FromJson<StockData>(jsonString);
              // Use your parsed data here!
          }
      }
  }
  

内容的提问来源于stack exchange，提问作者Bruck Film