#552 add some log when crawler stop

webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java

@@ -303,7 +303,7 @@ public class Spider implements Runnable, Task {
     public void run() {
         checkRunningStat();
         initComponent();
-        logger.info("Spider " + getUUID() + " started!");
+        logger.info("Spider {} started!",getUUID());
         while (!Thread.currentThread().isInterrupted() && stat.get() == STAT_RUNNING) {
             final Request request = scheduler.poll(this);
             if (request == null) {
@@ -335,6 +335,7 @@ public class Spider implements Runnable, Task {
         if (destroyWhenExit) {
             close();
         }
+        logger.info("Spider {} closed! {} pages downloaded.", getUUID(), pageCount.get());
     }
 
     protected void onError(Request request) {