bug fixed for validateConnection

src/main/java/com/alibaba/druid/pool/ValidConnectionCheckerAdapter.java

@@ -16,8 +16,12 @@
 package com.alibaba.druid.pool;
 
 import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.Statement;
 import java.util.Properties;
 
+import com.alibaba.druid.util.JdbcUtils;
+
 /**
  * @author wenshao [szujobs@hotmail.com]
  * @since 0.2.21
@@ -25,8 +29,24 @@ import java.util.Properties;
 public class ValidConnectionCheckerAdapter implements ValidConnectionChecker {
 
     @Override
-    public boolean isValidConnection(Connection c, String query, int validationQueryTimeout) throws Exception {
-        return true;
+    public boolean isValidConnection(Connection conn, String query, int validationQueryTimeout) throws Exception {
+        if (query == null || query.length() == 0) {
+            return true;
+        }
+        
+        Statement stmt = null;
+        ResultSet rs = null;
+        try {
+            stmt = conn.createStatement();
+            if (validationQueryTimeout > 0) {
+                stmt.setQueryTimeout(validationQueryTimeout);
+            }
+            rs = stmt.executeQuery(query);
+            return true;
+        } finally {
+            JdbcUtils.close(rs);
+            JdbcUtils.close(stmt);
+        }
     }
 
     @Override

src/test/java/com/alibaba/druid/bvt/pool/basic/DataSourceTest3.java

@@ -325,16 +325,8 @@ public class DataSourceTest3 extends TestCase {
         dataSource.setValidationQuery(null);
         dataSource.setValidConnectionChecker(new MySqlValidConnectionChecker());
 
-        {
-            Exception error = null;
-            try {
-                DruidPooledConnection conn = dataSource.getConnection().unwrap(DruidPooledConnection.class);
-                dataSource.validateConnection(conn);
-            } catch (SQLException ex) {
-                error = ex;
-            }
-            Assert.assertNotNull(error);
-        }
-        
+        DruidPooledConnection conn = dataSource.getConnection().unwrap(DruidPooledConnection.class);
+        dataSource.validateConnection(conn);
+
     }
 }