change

src/connector/jdbc/src/main/java/com/taosdata/jdbc/AbstractConnection.java

@@ -290,7 +290,21 @@ public abstract class AbstractConnection extends WrapperImpl implements Connecti
     }
 
     @Override
-    public abstract boolean isValid(int timeout) throws SQLException;
+    public boolean isValid(int timeout) throws SQLException {
+        if (isClosed())
+            return false;
+        if (timeout < 0)
+            throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_INVALID_VARIABLE);
+
+        int status;
+        try (Statement stmt = createStatement()) {
+            ResultSet resultSet = stmt.executeQuery("select server_status()");
+            resultSet.next();
+            status = resultSet.getInt("server_status()");
+            resultSet.close();
+        }
+        return status == 1 ? true : false;
+    }
 
     @Override
     public void setClientInfo(String name, String value) throws SQLClientInfoException {

src/connector/jdbc/src/main/java/com/taosdata/jdbc/TSDBConnection.java

@@ -142,8 +142,9 @@ public class TSDBConnection extends AbstractConnection {
         throw TSDBError.createSQLException(TSDBErrorNumbers.ERROR_UNSUPPORTED_METHOD);
     }
 
-    public boolean isValid(int timeout) throws SQLException {
-        return !this.isClosed();
-    }
+//    @Override
+//    public boolean isValid(int timeout) throws SQLException {
+//        return !this.isClosed();
+//    }
 
 }

src/connector/jdbc/src/main/java/com/taosdata/jdbc/rs/RestfulConnection.java

@@ -357,9 +357,8 @@ public class RestfulConnection implements Connection {
     public boolean isValid(int timeout) throws SQLException {
         if (timeout < 0)
             throw new SQLException(TSDBConstants.INVALID_VARIABLES);
-        // TODO:
-        /* The driver shall submit a query on the connection or use some other mechanism that positively verifies
-         the connection is still valid when this method is called.*/
+        // TODO: The driver shall submit a query on the connection or use some other mechanism
+        //  that positively verifies the connection is still valid when this method is called.
         return !isClosed();
     }
 

src/connector/jdbc/src/test/java/com/taosdata/jdbc/TSDBConnectionTest.java

@@ -187,12 +187,15 @@ public class TSDBConnectionTest {
     public void createNClob() {
     }
 
-    @Test
-    public void createSQLXML() {
+    @Test(expected = SQLFeatureNotSupportedException.class)
+    public void createSQLXML() throws SQLException {
+        conn.createSQLXML();
     }
 
     @Test
-    public void isValid() {
+    public void isValid() throws SQLException {
+        Assert.assertTrue(conn.isValid(1000));
+        conn.isValid(0);
     }
 
     @Test