mvvmcross使用文件插件和json序列化/反序列化保持程序设置

Question

我正在尝试使用fileplugin和json序列化程序来做这件事。在核心项目中，我有以下DcsSetup类。现在我使用的是droid。我似乎无法保存该文件。json序列化没问题。WriteFile似乎没问题，但下次我尝试使用TryReadTextFile读取该文件时，它会失败。我在设备上找不到文件，所以我认为WriteFile的东西是错误的。在Android上保存和读取设置类的正确方法是什么？

公共类DcsSetup {

public class Settings
{
    //Server
    public string Server;
    public int Port;

    public int Device;

    public string EncodingFromClient;
    public string EncodingToClient;

    public int FontCorrectionPixelsWidth; //Pixels to add or subtract i Y dimension to get the right font size 
    public int FontCorrectionPixelsHeight; //Pixels to add or subtract i Y dimension to get the right font size 

    public float XPct;//Pct to add to vertical placement of textBox and Buttons.
    public float YPct;//Pct to add to horisontal placement of textBox and Buttons.
    public float SizePct;//Pct to add to horisontal size of textBox and Buttons.

    public bool FullScreen;
    public bool DontSleep;


    //Diverse
    public bool AutoSendEnter;
}
public Settings Setting;

public DcsSetup()
{
  var setupFound=true;
  var fileService = Mvx.Resolve<IMvxFileStore>();
  var jsonConvert = Mvx.Resolve<IMvxJsonConverter>();
  var path = fileService.PathCombine("Setting", "Settings.txt");

  Setting = new Settings();

  try {
    string settingFile;
    if (fileService.TryReadTextFile(path, out settingFile)){
      Setting = jsonConvert.DeserializeObject<Settings>(settingFile);
    } else{
      setupFound = false;
    }
  }
  catch(Exception e) {
     AppTrace.Error("Failed to read settings: {0}", e.Message);
     setupFound=false;
  }
    if(setupFound==false){
        Setting.Server = "192.168.1.100";
        Setting.Port = 1650;

        Setting.Device = 1;

        Setting.EncodingFromClient = "CP1252";
        Setting.EncodingToClient = "CP1252";

        Setting.FontCorrectionPixelsWidth = 0;
        Setting.FontCorrectionPixelsHeight = 0;

        Setting.XPct = 97.0f;
        Setting.YPct = 100.0f;
        Setting.SizePct = 98.0f;

        Setting.FullScreen = false;
        Setting.DontSleep = true;
        Setting.AutoSendEnter = true;

        try {
          //json
          var json = jsonConvert.SerializeObject(Setting);
          fileService.EnsureFolderExists("Setting");

          fileService.WriteFile(path, json);
        }
        catch (Exception e) {
          AppTrace.Error("Failed to save settings: {0}", e.Message);
        }
    }
}

}}

Answer 1

我刚刚使用MvvmCross的3.1.1-beta2包在VS2012中创建了一个项目

然后我添加了File和Json插件包

我将核心FirstViewModel更改为：

public class FirstViewModel 
    : MvxViewModel
{
    private readonly IMvxFileStore _fileStore;
    private readonly IMvxJsonConverter _jsonConverter;
    private readonly string _filePath;

    public class ToStore
    {
        public string Foo { get; set; }
    }

    public ICommand SaveCommand
    {
        get
        {
            return new MvxCommand(() =>
                {
                    var toStore = new ToStore() {Foo = Hello};
                    var json = _jsonConverter.SerializeObject(toStore);
                    _fileStore.WriteFile(_filePath, json);   
                });
        }
    }

    public ICommand LoadCommand
    {
        get
        {
            return new MvxCommand(() =>
                {
                    string txt;
                    if (_fileStore.TryReadTextFile(_filePath, out txt))
                    {
                        Mvx.Trace("Loaded {0}", txt);
                        var stored = _jsonConverter.DeserializeObject<ToStore>(txt);
                        Hello = stored.Foo;
                    }
                });
        }
    }

    private string _hello = "Hello MvvmCross";

    public FirstViewModel(IMvxFileStore fileStore, IMvxJsonConverter jsonConverter)
    {
        _fileStore = fileStore;
        _jsonConverter = jsonConverter;
        _filePath = _fileStore.PathCombine("SubDir", "MyFile.txt");
        _fileStore.EnsureFolderExists("SubDir");
    }

    public string Hello
    { 
        get { return _hello; }
        set { _hello = value; RaisePropertyChanged(() => Hello); }
    }
}

我在一个测试Android UI中调用了这个：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:local="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
  <EditText
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textSize="40dp"
    local:MvxBind="Text Hello"
    />
  <TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textSize="40dp"
    local:MvxBind="Text Hello"
    />
  <Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textSize="40dp"
    android:text="Load"
    local:MvxBind="Click LoadCommand"
    />
  <Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textSize="40dp"
    android:text="Save"
    local:MvxBind="Click SaveCommand"
    />
</LinearLayout>

这似乎工作得很好-它在测试运行期间和测试运行之间保存和加载了JSON。

基于此，我唯一的猜测是你是否在两次运行之间重新部署应用程序-如果你这样做了，并且你没有检查MonoDroid的Preserve application data/cache on device between deploys，那么你将看不到保留的设置。