Xamarin.Android 讀取AboutAssets.txt

讀取AboutAssets.txt

使用Activity上下文讀取

// 須要把AboutAssets.txt的Build Action屬性設置爲AndroidAsset（https://developer.xamarin.com/guides/android/application_fundamentals/resources_in_android/part_6_-_using_android_assets/）
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        TextView tv = new TextView(this);

        //使用Activity上下文讀取
        string content;
        AssetManager assets = this.Assets;
        using (StreamReader sr = new StreamReader(assets.Open("AboutAssets.txt")))
        {
            content = sr.ReadToEnd();
        }
        tv.Text = content;
        SetContentView(tv);
    }

不使用Activity上下文讀取

1. 建立Application子類並使用[Application]標籤設置爲當前程序的Application

   [Application]
       public class DemoApplication:Application
       {
   
            public DemoApplication(IntPtr handle, JniHandleOwnership ownerShip) : base(handle, ownerShip)
           {
   
           }
           public static volatile Context s_appContext = null;
   
           public override void OnConfigurationChanged(Configuration newConfig)
           {
               base.OnConfigurationChanged(newConfig);
           }
   
           public override void OnCreate()
           {
               base.OnCreate();
               s_appContext = this.ApplicationContext;
           }
   
           public override void OnLowMemory()
           {
               base.OnLowMemory();
           }
   
           public override void OnTerminate()
           {
               base.OnTerminate();
           }
       }

2. 讀取

   /// <summary>
   /// 讀取Assets文件夾下的文件（Assets文件夾能夠有子文件夾）
   /// 須要把AboutAssets.txt的Build Action屬性設置爲AndroidAsset（https://developer.xamarin.com/guides/android/application_fundamentals/resources_in_android/part_6_-_using_android_assets/）
   /// DemoApplication 繼承自Android.Application使用[Application]標籤設置爲當前程序的Application
   /// </summary>
   /// <returns></returns>
   public string ReadFromAssetsWithoutActivityContext()
   {
       string content;
       AssetManager am = ProXamarinAndroid.s_appContext.Assets;
       using (StreamReader sr = new StreamReader(am.Open("AboutAssets.txt"))) 
       {
           content = sr.ReadToEnd();
       }
       return content;
   }

3. 調用

   protected override void OnCreate(Bundle savedInstanceState)
       {
           base.OnCreate(savedInstanceState);
           TextView tv = new TextView(this);
           //不使用Activity上下文讀取
           tv.Text = ReadFromAssetsWithoutActivityContext();
           SetContentView(tv);
       }