Spring Boot集成Druid出现异常报错的原因及解决

discard long time none received connection. , jdbcUrl : jdbc:mysql://******?useSSL=false&allowPublicKeyRetrieval=true&useUnicode=true&characterEncoding=UTF-8, version : 1.2.3, lastPacketReceivedIdleMillis : 172675

if (valid && isMySql) { // unexcepted branch
    long lastPacketReceivedTimeMs = MySqlUtils.getLastPacketReceivedTimeMs(conn);
    if (lastPacketReceivedTimeMs > 0) {
        long mysqlIdleMillis = currentTimeMillis - lastPacketReceivedTimeMs;
        if (lastPacketReceivedTimeMs > 0 //
                && mysqlIdleMillis >= timeBetweenEvictionRunsMillis) {
            discardConnection(holder);
            String errorMsg = "discard long time none received connection. "
                    + ", jdbcUrl : " + jdbcUrl
                    + ", jdbcUrl : " + jdbcUrl
                    + ", lastPacketReceivedIdleMillis : " + mysqlIdleMillis;
            LOG.error(errorMsg);
            return false;
        }
    }
}

boolean valid = validConnectionChecker.isValidConnection(conn, validationQuery, validationQueryTimeout);

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 void configFromProperties(Properties properties) {
    String property = properties.getProperty("druid.mysql.usePingMethod");
    if ("true".equals(property)) {
        setUsePingMethod(true);
    } else if ("false".equals(property)) {
        setUsePingMethod(false);
    }
}

static {
    System.setProperty("druid.mysql.usePingMethod","false");
}

/*
* 解决druid 日志报错：discard long time none received connection:xxx
* */
@PostConstruct
public void setProperties(){
    System.setProperty("druid.mysql.usePingMethod","false");
}