正如Dai所说的，您可以使用UnityWebRequest来实现这一点。您几乎没有发送它的选项。

private const string YourApiKey = "3152-6969-1337";

void Start()
{
    var json = "{\"prompt\": \"A cute baby sea otter\",\"n\": 2,\"size\": \"1024x1024\"}";
    StartCoroutine(FillAndSend(json));
}

public IEnumerator FillAndSend(string json)
{
    using (var request = new UnityWebRequest("https://api.openai.com/v1/images/generations", "POST"))
    {
        request.SetRequestHeader("Content-Type", "application/json");
        request.SetRequestHeader("Authorization", $"Bearer {YourApiKey}");
        request.SetRequestHeader("Accept", " text/plain");

        request.uploadHandler = new UploadHandlerRaw(Encoding.UTF8.GetBytes(json));
        request.downloadHandler = new DownloadHandlerBuffer(); // You can also download directly PNG or other stuff easily. Check here for more information: https://docs.unity3d.com/Manual/UnityWebRequest-CreatingDownloadHandlers.html

        yield return request.SendWebRequest();

        if (request.isNetworkError || request.isHttpError) // Depending on your Unity version, it will tell that these are obsolote. You can try this: request.result != UnityWebRequest.Result.Success
        {
            Debug.LogError(request.error);
            yield break;
        }

        Debug.Log(request.downloadHandler.text);
        var response = request.downloadHandler.data; // Or you can directly get the raw binary data, if you need.
    }
}

你也可以使用UnityWebRequest.Post(string uri, string postData)方法，或者你可以使用WWWForm类来发布表单，而不是JSON等。
你也可以为你的数据创建一个模型类，然后把prompt、n和size属性放入其中。然后，你可以用JsonUtility.ToJson(dalleRequest)把它转换成JSON。或者，如果你愿意，你可以把这些值作为方法的参数，然后在发送请求的同时创建字符串。