学习笔记

1.Liunx防火墙入门，C段，B类

service  iptables status

service  iptables start

service  iptables service

service  iptables stop

service  iptables save

2.sftp一个端口，ftp两个端口 21和数据传输端口

3.关联查优化：首先配合explain加索引，然后inner join让B最简单（仅过滤那几个字段）

最优化：不关联查，子查询不能使用索引，性能差，尽量集中一张表里查

4.获取协议、ip、端口、路径：

logger.info("ip={},port={},context={},http={}", NetworkUtils.getLocalIP(), NetworkUtils.getLocalPort(), req.getContextPath(),req.getScheme());

public class NetworkUtils {
    /**
     * 获取当前机器端口号
     */
    public static String getLocalPort() throws Exception {
        MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer();
        Set<ObjectName> objectNames = mBeanServer.queryNames(new ObjectName("*:type=Connector,*"), null);
        if (objectNames == null || objectNames.size() <= 0) {
            throw new IllegalStateException("Cannot get the names of MBeans controlled by the MBean server.");
        }

        for (ObjectName objectName : objectNames) {
            String protocol = String.valueOf(mBeanServer.getAttribute(objectName, "protocol"));
            String port = String.valueOf(mBeanServer.getAttribute(objectName, "port"));
            // windows下属性名称为HTTP/1.1, linux下为org.apache.coyote.http11.Http11NioProtocol
            if (protocol.equals("HTTP/1.1") || protocol.equals("org.apache.coyote.http11.Http11NioProtocol")) {
                return port;
            }
        }

        throw new IllegalStateException("Failed to get the HTTP port of the current server");
    }

    /**
     * 获取当前机器的IP
     */
    public static String getLocalIP() throws Exception {
        InetAddress addr = InetAddress.getLocalHost();
        byte[] ipAddr = addr.getAddress();
        String ipAddrStr = "";
        for (int i = 0; i < ipAddr.length; i++) {
            if (i > 0) {
                ipAddrStr += ".";
            }
            ipAddrStr += ipAddr[i] & 0xFF;
        }

        return ipAddrStr;
    }
}

/**
  * 获取当前机器的IP4地址
  */

public static String getLocalIP() throws Exception {
    try{
        Enumeration<NetworkInterface> allNetInterfaces = NetworkInterface.getNetworkInterfaces();
        while (allNetInterfaces.hasMoreElements()){
            NetworkInterface netInterface = (NetworkInterface) allNetInterfaces.nextElement();
            Enumeration<InetAddress> addresses = netInterface.getInetAddresses();
            while (addresses.hasMoreElements()){
                InetAddress ip = (InetAddress) addresses.nextElement();
                if (ip != null
                        && ip instanceof Inet4Address
                        && !ip.isLoopbackAddress() //loopback地址即本机地址，IPv4的loopback范围是127.0.0.0 ~ 127.255.255.255
                        && ip.getHostAddress().indexOf(":")==-1){
                    System.out.println("本机的IP = " + ip.getHostAddress());
                    return ip.getHostAddress();
                }
            }
        }
    }catch(Exception e){
        e.printStackTrace();
    }

    return null;
}