Unity3d使用JsonUtility.FromJson读取json文件

        使用JsonUtility.FromJson方法不需要额外引用第三方库。该方法只能读取json对象，而不能读取json数组。

        假如我们有如下的json数组：

[
{"id":1, "name":"first2021", "level":5, "score":100, "isUser":false},
{"id":2, "name":"second2022", "level":5, "score":90, "isUser":false},
{"id":3, "name":"third2023", "level":5, "score":50, "isUser":false},
{"id":4, "name":"fourth2024", "level":5, "score":30, "isUser":true},
{"id":5, "name":"fifth2025", "level":5, "score":20, "isUser":false},
{"id":6, "name":"sixth2026", "level":5, "score":10, "isUser":false}
]

        需要调整为：

{"rankDatas":[
{"id":1, "name":"first2021", "level":5, "score":100, "isUser":false},
{"id":2, "name":"second2022", "level":5, "score":90, "isUser":false},
{"id":3, "name":"third2023", "level":5, "score":50, "isUser":false},
{"id":4, "name":"fourth2024", "level":5, "score":30, "isUser":true},
{"id":5, "name":"fifth2025", "level":5, "score":20, "isUser":false},
{"id":6, "name":"sixth2026", "level":5, "score":10, "isUser":false}
]}

        我们将该文件放到Resources的json目录下，如下图所示：

我们创建RankData类存放反序列化之后的数据：

[System.Serializable]
public class RankData
{
    public int id;
    public string name;
    public int level;
    public int score;
    public bool isUser;
}

[System.Serializable]
public class RankDataList
{
    public RankData[] rankDatas;
}

其中RankDataList -> rankDatas的名字必须和json文件中最外层的key保持一致，否则会读取不到数据。

读取json文件并解析的逻辑如下：

 TextAsset jsonText = Resources.Load<TextAsset>("json/rank_info");
 if(jsonText != null)
 {
     string jsonData = jsonText.text;
     Debug.Log(jsonData);
     RankDataList rankDataList = JsonUtility.FromJson<RankDataList>(jsonData);

     foreach(var item in rankDataList.rankDatas)
     {
         Debug.Log("id:" + item.id);
     }
 }
 else
 {
     Debug.LogError("Can't find JSON file.");
 }