Fix shutdown bug

Signed-off-by: Leo Ma <begeekmyfriend@gmail.com>

app/src/main/java/net/ossrs/yasea/rtmp/io/RtmpConnection.java

@@ -301,6 +301,7 @@ public class RtmpConnection implements RtmpPublisher {
 
     @Override
     public void shutdown() {
+        if (socket != null) {
             try {
                 // It will raise EOFException in handleRxPacketThread
                 socket.shutdownInput();
@@ -322,18 +323,17 @@ public class RtmpConnection implements RtmpPublisher {
             }
 
             // shutdown socket as well as its input and output stream
-        if (socket != null) {
             try {
                 socket.close();
                 Log.d(TAG, "socket closed");
             } catch (IOException ex) {
                 Log.e(TAG, "shutdown(): failed to close socket", ex);
             }
-        }
 
             reset();
             mHandler.onRtmpDisconnected("disconnected");
         }
+    }
 
     private void reset() {
         connected = false;