From 94eef043f52995c4d29832f6fc0599f86023d1d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=AB=98=E9=93=81?= <shaojin.wensj@alibaba-inc.com>
Date: Thu, 5 May 2016 17:44:38 +0800
Subject: [PATCH] handle MBean preRegister method, if exists, unregister.

---
 .../java/com/alibaba/druid/pool/DruidDataSource.java  | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/alibaba/druid/pool/DruidDataSource.java b/src/main/java/com/alibaba/druid/pool/DruidDataSource.java
index 8279d8fe3b..fa36a698c7 100644
--- a/src/main/java/com/alibaba/druid/pool/DruidDataSource.java
+++ b/src/main/java/com/alibaba/druid/pool/DruidDataSource.java
@@ -2879,8 +2879,15 @@ public class DruidDataSource extends DruidAbstractDataSource
     
     @Override
     public ObjectName preRegister(MBeanServer server, ObjectName name) throws Exception {
-        //do nothing
-        //return original name to avoid NullPointerException
+        if (server != null) {
+            try {
+                if (server.isRegistered(name)) {
+                    server.unregisterMBean(name);
+                }
+            } catch (Exception ex) {
+                LOG.warn("DruidDataSource preRegister error", ex);
+            }
+        }
         return name;
     }