BI-100757 fix:使用自定义驱动，mysql数据连接连接不上

fine-druid/src/main/java/com/fr/third/alibaba/druid/util/MySqlUtils.java

@@ -357,7 +357,6 @@ public class MySqlUtils {
         }
 
         Class<?> clazz = conn.getClass();
-        if (class_ConnectionImpl == null) {
         if (clazz.getName().equals("com.mysql.jdbc.ConnectionImpl")) {
             class_ConnectionImpl = clazz;
         } else if (clazz.getName().equals("com.mysql.jdbc.Connection")) { // mysql 5.0.x
@@ -367,7 +366,6 @@ public class MySqlUtils {
         } else if (clazz.getSuperclass().getName().equals("com.mysql.jdbc.ConnectionImpl")) {
             class_ConnectionImpl = clazz.getSuperclass();
         }
-        }
 
         if (class_ConnectionImpl == clazz || class_ConnectionImpl == clazz.getSuperclass()) {
             try {
@@ -387,7 +385,7 @@ public class MySqlUtils {
     }
 
     public static long getLastPacketReceivedTimeMs(Connection conn) throws SQLException {
-        if (class_connectionImpl == null && !class_connectionImpl_Error) {
+        if (!class_connectionImpl_Error) {
             try {
                 class_connectionImpl = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
                 if (class_connectionImpl == null) {
@@ -406,9 +404,7 @@ public class MySqlUtils {
         }
 
         if(mysqlJdbcVersion6){
-            if (classJdbc == null) {
             classJdbc = Utils.loadClass("com.mysql.cj.jdbc.JdbcConnection");
-            }
 
             if (classJdbc == null) {
                 return -1;
@@ -441,7 +437,7 @@ public class MySqlUtils {
                 throw new SQLException("getIdleFor error", e);
             }
         } else {
-            if (method_getIO == null && !method_getIO_error) {
+            if (!method_getIO_error) {
                 try {
                     method_getIO = class_connectionImpl.getMethod("getIO");
                 } catch (Throwable error) {
@@ -453,7 +449,7 @@ public class MySqlUtils {
                 return -1;
             }
 
-            if (class_MysqlIO == null && !class_MysqlIO_Error) {
+            if (!class_MysqlIO_Error) {
                 try {
                     class_MysqlIO = Utils.loadClass("com.mysql.jdbc.MysqlIO");
                 } catch (Throwable error) {
@@ -465,7 +461,7 @@ public class MySqlUtils {
                 return -1;
             }
 
-            if (method_getLastPacketReceivedTimeMs == null && !method_getLastPacketReceivedTimeMs_error) {
+            if (!method_getLastPacketReceivedTimeMs_error) {
                 try {
                     Method method = class_MysqlIO.getDeclaredMethod("getLastPacketReceivedTimeMs");
                     method.setAccessible(true);

fine-druid/src/main/java/com/fr/third/alibaba/druid/util/Utils.java

@@ -239,20 +239,20 @@ public class Utils {
             return null;
         }
 
+        ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
+        if (ctxClassLoader != null) {
             try {
-            return Class.forName(className);
+                return clazz = ctxClassLoader.loadClass(className);
             } catch (ClassNotFoundException e) {
                 // skip
             }
+        }
 
-        ClassLoader ctxClassLoader = Thread.currentThread().getContextClassLoader();
-        if (ctxClassLoader != null) {
         try {
-                clazz = ctxClassLoader.loadClass(className);
+            clazz = Class.forName(className);
         } catch (ClassNotFoundException e) {
             // skip
         }
-        }
 
         return clazz;
     }