Divided the code into functional modules

Models/HeartRateDataPoint.cs

@@ -0,0 +1,11 @@
+namespace HeartRateMonitorAndroid.Models
+{
+    /// <summary>
+    /// 心率数据点类
+    /// </summary>
+    public class HeartRateDataPoint
+    {
+        public DateTime Timestamp { get; set; }
+        public int HeartRate { get; set; }
+    }
+}