CAMEL-23289: Fix empty catch blocks and resource leaks in DrillProducer

components/camel-drill/pom.xml

@@ -72,6 +72,12 @@
             <optional>true</optional>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${mockito-version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
 </project>

components/camel-drill/src/main/java/org/apache/camel/component/drill/DrillProducer.java

@@ -54,35 +54,24 @@ protected void doStart() throws Exception {
     protected void doStop() throws Exception {
         super.doStop();
 
-        try {
-            connection.close();
-        } catch (Exception e) {
+        if (connection != null) {
+            try {
+                connection.close();
+            } catch (Exception e) {
+                LOG.debug("Error closing JDBC connection: {}", e.getMessage(), e);
+            }
         }
     }
 
     @Override
     public void process(final Exchange exchange) throws Exception {
         final String query = exchange.getIn().getHeader(DrillConstants.DRILL_QUERY, String.class);
 
-        // check query
-        Statement st = null;
-        ResultSet rs = null;
-        try {
-            st = connection.createStatement();
-            rs = st.executeQuery(query);
-
+        try (Statement st = connection.createStatement();
+             ResultSet rs = st.executeQuery(query)) {
             exchange.getIn().setBody(endpoint.queryForList(rs));
-        } finally {
-            try {
-                rs.close();
-            } catch (Exception e) {
-            }
-            try {
-                st.close();
-            } catch (Exception e) {
-            }
         }
-    } // end process
+    }
 
     private void createJDBCConnection() throws ClassNotFoundException, SQLException {
         Class.forName(DrillConstants.DRILL_DRIVER);

components/camel-drill/src/test/java/org/apache/camel/component/drill/DrillProducerTest.java

@@ -0,0 +1,130 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.component.drill;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Collections;
+
+import org.apache.camel.Exchange;
+import org.apache.camel.Message;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+class DrillProducerTest {
+
+    private DrillEndpoint endpoint;
+    private Connection connection;
+    private Statement statement;
+    private ResultSet resultSet;
+    private Exchange exchange;
+    private Message message;
+
+    @BeforeEach
+    void setUp() {
+        endpoint = mock(DrillEndpoint.class);
+        when(endpoint.getCamelContext()).thenReturn(null);
+        when(endpoint.getEndpointUri()).thenReturn("drill://localhost");
+
+        connection = mock(Connection.class);
+        statement = mock(Statement.class);
+        resultSet = mock(ResultSet.class);
+        exchange = mock(Exchange.class);
+        message = mock(Message.class);
+
+        when(exchange.getIn()).thenReturn(message);
+    }
+
+    @Test
+    void testProcessClosesStatementAndResultSet() throws Exception {
+        String query = "SELECT * FROM test";
+        when(message.getHeader(DrillConstants.DRILL_QUERY, String.class)).thenReturn(query);
+        when(connection.createStatement()).thenReturn(statement);
+        when(statement.executeQuery(query)).thenReturn(resultSet);
+        when(endpoint.queryForList(any(ResultSet.class))).thenReturn(Collections.emptyList());
+
+        DrillProducer producer = new DrillProducer(endpoint);
+        setConnection(producer, connection);
+
+        producer.process(exchange);
+
+        verify(resultSet).close();
+        verify(statement).close();
+    }
+
+    @Test
+    void testProcessClosesResourcesOnQueryFailure() throws Exception {
+        String query = "SELECT * FROM test";
+        when(message.getHeader(DrillConstants.DRILL_QUERY, String.class)).thenReturn(query);
+        when(connection.createStatement()).thenReturn(statement);
+        when(statement.executeQuery(query)).thenThrow(new SQLException("query failed"));
+
+        DrillProducer producer = new DrillProducer(endpoint);
+        setConnection(producer, connection);
+
+        try {
+            producer.process(exchange);
+        } catch (SQLException e) {
+            // expected
+        }
+
+        verify(statement).close();
+    }
+
+    @Test
+    void testDoStopClosesConnection() throws Exception {
+        DrillProducer producer = new DrillProducer(endpoint);
+        setConnection(producer, connection);
+
+        producer.doStop();
+
+        verify(connection).close();
+    }
+
+    @Test
+    void testDoStopHandlesCloseException() throws Exception {
+        doThrow(new SQLException("close failed")).when(connection).close();
+
+        DrillProducer producer = new DrillProducer(endpoint);
+        setConnection(producer, connection);
+
+        // should not throw
+        producer.doStop();
+
+        verify(connection).close();
+    }
+
+    @Test
+    void testDoStopHandlesNullConnection() throws Exception {
+        DrillProducer producer = new DrillProducer(endpoint);
+        setConnection(producer, null);
+
+        // should not throw
+        producer.doStop();
+    }
+
+    private void setConnection(DrillProducer producer, Connection conn) throws Exception {
+        java.lang.reflect.Field field = DrillProducer.class.getDeclaredField("connection");
+        field.setAccessible(true);
+        field.set(producer, conn);
+    }
+}