if (testWhileIdle) {
    final DruidConnectionHolder holder = poolableConnection.holder;
    long currentTimeMillis             = System.currentTimeMillis();
    long lastActiveTimeMillis          = holder.lastActiveTimeMillis;
    long lastExecTimeMillis            = holder.lastExecTimeMillis;
    long lastKeepTimeMillis            = holder.lastKeepTimeMillis;
    if (checkExecuteTime
            && lastExecTimeMillis != lastActiveTimeMillis) {
        lastActiveTimeMillis = lastExecTimeMillis;
    }
    if (lastKeepTimeMillis > lastActiveTimeMillis) {
        lastActiveTimeMillis = lastKeepTimeMillis;
    }
    long idleMillis    = currentTimeMillis - lastActiveTimeMillis;
    long timeBetweenEvictionRunsMillis = this.timeBetweenEvictionRunsMillis;
    if (timeBetweenEvictionRunsMillis <= 0) {
        timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
    }
    if (idleMillis >= timeBetweenEvictionRunsMillis
            || idleMillis < 0 // unexcepted branch
            ) {
        boolean validate = testConnectionInternal(poolableConnection.holder, poolableConnection.conn);
        if (!validate) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("skip not validate connection.");
            }
            discardConnection(poolableConnection.holder);
             continue;
        }
    }
}

public static ReplicationConnection createProxyInstance(List<String> masterHostList, Properties masterProperties, List<String> slaveHostList,
            Properties slaveProperties) throws SQLException {
      ReplicationConnectionProxy connProxy = new ReplicationConnectionProxy(masterHostList, masterProperties, slaveHostList, slaveProperties);
      return (ReplicationConnection) java.lang.reflect.Proxy.newProxyInstance(ReplicationConnection.class.getClassLoader(), INTERFACES_TO_PROXY, connProxy);
 }

public boolean isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) throws Exception {
    if (conn.isClosed()) {
        return false;
    }
    if (usePingMethod) {
        if (conn instanceof DruidPooledConnection) {
            conn = ((DruidPooledConnection) conn).getConnection();
        }
        if (conn instanceof ConnectionProxy) {
            conn = ((ConnectionProxy) conn).getRawObject();
        }
        if (clazz.isAssignableFrom(conn.getClass())) {
            if (validationQueryTimeout <= 0) {
                validationQueryTimeout = DEFAULT_VALIDATION_QUERY_TIMEOUT;
            }
            try {
                ping.invoke(conn, true, validationQueryTimeout * 1000);
            } catch (InvocationTargetException e) {
                Throwable cause = e.getCause();
                if (cause instanceof SQLException) {
                    throw (SQLException) cause;
                }
                throw e;
            }
            return true;
        }
    }
    String query = validateQuery;
    if (validateQuery == null || validateQuery.isEmpty()) {
        query = DEFAULT_VALIDATION_QUERY;
    }
    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);
    }
}

public MySqlValidConnectionChecker(){
try {
        clazz = Utils.loadClass("com.mysql.jdbc.MySQLConnection");
        if (clazz == null) {
            clazz = Utils.loadClass("com.mysql.cj.jdbc.ConnectionImpl");
        }
        if (clazz != null) {
            ping = clazz.getMethod("pingInternal", boolean.class, int.class);
        }
        if (ping != null) {
            usePingMethod = true;
        }
    } catch (Exception e) {
        LOG.warn("Cannot resolve com.mysql.jdbc.Connection.ping method.  Will use 'SELECT 1' instead.", e);
    }
    configFromProperties(System.getProperties());
}
@Override
public void configFromProperties(Properties properties) {
    String property = properties.getProperty("druid.mysql.usePingMethod");
    if ("true".equals(property)) {
        setUsePingMethod(true);
    } else if ("false".equals(property)) {
        setUsePingMethod(false);
    }
}

public class MySqlReplicationCompatibleValidConnectionChecker extends MySqlValidConnectionChecker {
    private static final Log LOG = LogFactory.getLog(MySqlValidConnectionChecker.class);
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Override
    public boolean isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) throws Exception {
        if (conn.isClosed()) {
            return false;
        }
        if (conn instanceof DruidPooledConnection) {
            conn = ((DruidPooledConnection) conn).getConnection();
        }
        if (conn instanceof ConnectionProxy) {
            conn = ((ConnectionProxy) conn).getRawObject();
        }
        if (conn instanceof ReplicationConnection) {
            try {
                ((ReplicationConnection) conn).ping();
                LOG.info("validate connection success: connection=" + conn.toString());
                return true;
            } catch (SQLException e) {
                LOG.error("validate connection error: connection=" + conn.toString(), e);
                throw e;
            }
        }
        return super.isValidConnection(conn, validateQuery, validationQueryTimeout);
    }
}