Xamarin android数据保存到json文件 [英] Xamarin android data saving to json file

问题描述

我需要在调用方法OnDestroy时保存文件，并在调用方法OnCreate时加载同一文件.目前，我可以轻松地从Assets中读取json文件(效果很好)

I need to save the file when method OnDestroy is called and load same file when method OnCreate is called. At this time I can read json file easily from Assets (this works fine)

StreamReader reader = new StreamReader(Assets.Open("reiksmes.json"));
string JSONstring = reader.ReadToEnd();
Daiktai myList = JsonConvert.DeserializeObject<Daiktai>(JSONstring);
items.Add(myList);

，但是当我尝试将(c3)类数据保存(写入)到上面打开的相同文件时，我遇到了一些问题.我试过了:

, but I have some problems when I try to save(write) Daiktai class data to the same file I opened above. I tried:

string data = JsonConvert.SerializeObject(items);
File.WriteAllText("Assets\\reiksmes.json", data);

尝试此操作会出现错误System.UnauthorizedAccessException: Access to the path "/Assets eiksmes.json" is denied.

with this try I get error System.UnauthorizedAccessException: Access to the path "/Assets eiksmes.json" is denied.

也尝试过:

string data = JsonConvert.SerializeObject(items);
StreamWriter writer = new StreamWriter(Assets.Open("reiksmes.json"));
writer.WriteLine(data);

并通过此尝试我得到错误System.ArgumentException: Stream was not writable.

摘要: 我想我选择了错误的目录(Assets)，我需要保存和加载数据(json格式).那么我需要在哪里保存它们以及如何保存(举个例子)?

Summary: I think I chose bad directory(Assets), I need to save and load data (json format). So where do I need to save them and how(give example)?

推荐答案

您无法将任何内容保存到资产中.您可以从中阅读.您必须将文件保存到其他文件夹.

You can't save anything to assets. You can just read from it. You have to save the file to a different folder.

        var fileName = "reiksmes.json";
        string documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal); // Documents folder
        var path = Path.Combine(documentsPath, fileName);

        Console.WriteLine(path);
        if (!File.Exists(path))
        {                
            var s = AssetManager.Open(fileName);
            // create a write stream
            FileStream writeStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Write);
            // write to the stream
            ReadWriteStream(s, writeStream);
        }

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