C# Java.GetBytes方法代码示例

		public static string GetMD5 (Java.Lang.String s)
		{
			try {
				// Create MD5 Hash
				var digest = Java.Security.MessageDigest.GetInstance ("MD5");
				digest.Update (s.GetBytes ());
				var messageDigest = digest.Digest ();

				// Create Hex String
				var hexString = new Java.Lang.StringBuffer ();
				for (int i = 0; i < messageDigest.Length; i++) {
					var h = Java.Lang.Integer.ToHexString (0xFF & messageDigest [i]);
					while (h.Length < 2) {
						h = "0" + h;
					}
					hexString.Append (h);
				}
				return hexString.ToString ();

			} catch (Java.Security.NoSuchAlgorithmException ex) {
				Log.Debug (TAG, ex.StackTrace);
			}
			return "";
		}

	    /**
	     * Only call this method from the main (UI) thread. The {@link OnFetchCompleteListener} callback
	     * be invoked on the UI thread, but image fetching will be done in an {@link AsyncTask}.
	     *
	     * @param cookie An arbitrary object that will be passed to the callback.
	     */
	    public static void FetchImage(Context context, Java.Lang.String url, BitmapFactory.Options decodeOptions, Java.Lang.Object cookie, Action<Bitmap> callback) 
		{
			
			Task.Factory.StartNew(() => {
				if(TextUtils.IsEmpty(url))
				{
					result = null;
					return;
				}
				
				File cacheFile = null;
				try
				{
					MessageDigest mDigest = MessageDigest.GetInstance("SHA-1");
					mDigest.Update(url.GetBytes());
					string cacheKey = BytesToHexString(mDigest.Digest());
					if(Environment.MediaMounted.Equals(Environment.ExternalStorageState))
					{
						cacheFile = new File(Environment.ExternalStorageDirectory +
						                     File.Separator + "Android " + 
						                     File.Separator + "data" +
						                     File.Separator + context.PackageName + 
						                     File.Separator + "cache" +
						                     File.Separator + "bitmap_" + cacheKey + ".tmp");
					}
				}
				catch (Exception e) 
				{
					// NoSuchAlgorithmException
					// Oh well, SHA-1 not available (weird), don't cache bitmaps.
				}
				
				if (cacheFile != null && cacheFile.Exists()) 
				{
	                Bitmap cachedBitmap = BitmapFactory.DecodeFile(cacheFile.ToString(), decodeOptions);
                    if (cachedBitmap != null) {
                        result = cachedBitmap;
						return;
                    }
                }
				
				try 
				{
				    // TODO: check for HTTP caching headers
					var client = new System.Net.WebClient();
					var image = client.DownloadData(new Uri(url.ToString()));
					if (image != null)
					{
						result = null;
						return;
					}
				
				    // Write response bytes to cache.
				    if (cacheFile != null) {
				        try {
				            cacheFile.ParentFile.Mkdirs();
				            cacheFile.CreateNewFile();
				            FileOutputStream fos = new FileOutputStream(cacheFile);
				            fos.Write(image);
				            fos.Close();
				        } catch (FileNotFoundException e) {
				            Log.Warn(TAG, "Error writing to bitmap cache: " + cacheFile.ToString(), e);
				        } catch (IOException e) {
				            Log.Warn(TAG, "Error writing to bitmap cache: " + cacheFile.ToString(), e);
				        }
				    }
				
				    // Decode the bytes and return the bitmap.
				    result = (BitmapFactory.DecodeByteArray(image, 0, image.Length, decodeOptions));
					return;
				} catch (Exception e) {
				    Log.Warn(TAG, "Problem while loading image: " + e.ToString(), e);
				}
                result = null;
			})
			.ContinueWith(task =>
				callback(result)
        	);
			
	    }

		/// <summary>
		/// Sends a message.
		/// </summary>
		/// <param name='message'>
		/// A string of text to send.
		/// </param>
		private void SendMessage (Java.Lang.String message)
		{
			// Check that we're actually connected before trying anything
			if (chatService.GetState () != BluetoothChatService.STATE_CONNECTED) {
				Toast.MakeText (this, Resource.String.not_connected, ToastLength.Short).Show ();
				return;
			}
	
			// Check that there's actually something to send
			if (message.Length () > 0) {
				// Get the message bytes and tell the BluetoothChatService to write
				byte[] send = message.GetBytes ();
				chatService.Write (send);
	
				// Reset out string buffer to zero and clear the edit text field
				outStringBuffer.SetLength (0);
				outEditText.Text = string.Empty;
			}
		}