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());}
@Overridepublic 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);    }
}