Add org.nativescript.Process.getUpTime() for android

android/widgets/src/main/java/org/nativescript/Process.java

@@ -0,0 +1,59 @@
+package org.nativescript;
+
+import android.os.SystemClock;
+import android.util.Log;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+
+/**
+ * Created by cankov on 15/05/2017.
+ */
+public class Process {
+    static long startTime = -1;
+
+    public static long getStartTime() {
+        if (startTime != -1) {
+            return startTime;
+        }
+
+        try {
+            int pid = android.os.Process.myPid();
+            final String path = "/proc/" + pid + "/stat";
+            final BufferedReader reader = new BufferedReader(new FileReader(path));
+            final String stat;
+            try {
+                stat = reader.readLine();
+            } finally {
+                reader.close();
+            }
+            final String field2End = ") ";
+            final String fieldSep = " ";
+            final int fieldStartTime = 20;
+            final int msInSec = 1000;
+
+            final String[] fields = stat.substring(stat.lastIndexOf(field2End)).split(fieldSep);
+            final long t = Long.parseLong(fields[fieldStartTime]);
+            int tckName;
+            try {
+                tckName = Class.forName("android.system.OsConstants").getField("_SC_CLK_TCK").getInt(null);
+            } catch (ClassNotFoundException e) {
+                tckName = Class.forName("libcore.io.OsConstants").getField("_SC_CLK_TCK").getInt(null);
+            }
+            final Object os = Class.forName("libcore.io.Libcore").getField("os").get(null);
+            final long tck = (Long) os.getClass().getMethod("sysconf", Integer.TYPE).invoke(os, tckName);
+            startTime = t * msInSec / tck;
+        } catch (Exception e) {
+            Log.v("JS", "Failed to get process start time. Using the current time as start time. Error: " + e);
+            startTime = SystemClock.elapsedRealtime();
+        }
+
+        return startTime;
+    }
+
+    public static long getUpTime() {
+        long startTime = getStartTime();
+        long currentTime = SystemClock.elapsedRealtime();
+        return currentTime - startTime;
+    }
+}