Pass exception to onError. Fixes #1005.

Author: sutra

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

@@ -320,7 +320,7 @@ public void run() {
                             processRequest(request);
                             onSuccess(request);
                         } catch (Exception e) {
-                            onError(request);
+                            onError(request, e);
                             logger.error("process request " + request + " error", e);
                         } finally {
                             pageCount.incrementAndGet();
@@ -338,10 +338,19 @@ public void run() {
         logger.info("Spider {} closed! {} pages downloaded.", getUUID(), pageCount.get());
     }
 
+    /**
+     * @deprecated Use {@link #onError(Request, Exception)} instead.
+     */
+    @Deprecated
     protected void onError(Request request) {
+    }
+
+    protected void onError(Request request, Exception e) {
+        this.onError(request);
+
         if (CollectionUtils.isNotEmpty(spiderListeners)) {
             for (SpiderListener spiderListener : spiderListeners) {
-                spiderListener.onError(request);
+                spiderListener.onError(request, e);
             }
         }
     }

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

@@ -10,5 +10,14 @@ public interface SpiderListener {
 
     public void onSuccess(Request request);
 
+    /**
+     * @deprecated Use {@link #onError(Request, Exception)} instead.
+     */
+    @Deprecated
     public void onError(Request request);
+
+    default void onError(Request request, Exception e) {
+        this.onError(request);
+    }
+
 }