fix bug: replay when entering app even if player is already playing.

Author: jonashao

app/src/main/java/com/junnanhao/next/player/Player.kt

@@ -18,6 +18,9 @@ class Player private constructor() : IPlayer {
         set
 
     override fun play(): Boolean {
+        if (isPlaying()) {
+            return true
+        }
         if (isPause) {
             player.start()
             isPause = false