add ValidConnectionChecker for JDBC4

core/src/main/java/com/alibaba/druid/pool/JDBC4ValidConnectionChecker.java

@@ -0,0 +1,27 @@
+package com.alibaba.druid.pool;
+
+import java.sql.Connection;
+import java.util.Properties;
+
+/**
+ * Common ValidConnectionChecker for JDBC4 to use Connection.isValid.
+ *
+ * @Author : kimmking(kimmking@apache.org)
+ * @create 2023/3/4 16:48
+ */
+public class JDBC4ValidConnectionChecker implements ValidConnectionChecker {
+
+    @Override
+    public boolean isValidConnection(Connection c, String query, int validationQueryTimeout) throws Exception {
+        Connection conn = c;
+        if(conn instanceof DruidPooledConnection) {
+            conn = ((DruidPooledConnection) conn).getConnection();
+        }
+        return conn.isValid(validationQueryTimeout);
+    }
+
+    @Override
+    public void configFromProperties(Properties properties) {
+
+    }
+}