当目标数据库不能直连的，需要一个服务器作为中间跳板的时候，我们需要通过SSH通道连接数据库，其使用方式如下：
引入依赖

    <!--SSH-->
        <dependency>
            <groupId>com.jcraft</groupId>
            <artifactId>jsch</artifactId>
            <version>0.1.55</version>
        </dependency>

编写SSHConnection连接类

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import java.util.Properties;

public class SSHConnection {

    private final static String S_PATH_FILE_KNOWN_HOSTS = "localhost";
    private final static int LOCAl_PORT = 3307;
    private final static int REMOTE_PORT = 3306;
    private final static int SSH_REMOTE_PORT = 22;
    private final static String SSH_USER = "root";
    private final static String SSH_PASSWORD = "123456";
    private final static String SSH_REMOTE_SERVER = "39.100.4.8";
    private final static String MYSQL_REMOTE_SERVER = "39.22.22.1";

    private Session sesion; //represents each ssh session

    public void closeSSH ()
    {
        sesion.disconnect();
    }

    public SSHConnection () throws Throwable
    {

        JSch jsch = null;

        jsch = new JSch();
        jsch.setKnownHosts(S_PATH_FILE_KNOWN_HOSTS);
        //jsch.addIdentity(S_PATH_FILE_PRIVATE_KEY);

        sesion = jsch.getSession(SSH_USER, SSH_REMOTE_SERVER, SSH_REMOTE_PORT);

        sesion.setPassword(SSH_PASSWORD);

        Properties config = new Properties();
        config.put("StrictHostKeyChecking", "no");
        sesion.setConfig(config);

        sesion.connect(); //ssh connection established!

        //by security policy, you must connect through a fowarded port
        sesion.setPortForwardingL(LOCAl_PORT, MYSQL_REMOTE_SERVER, REMOTE_PORT);

    }

}

编写MyContextListener监听

import org.springframework.stereotype.Component;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
@Component
public class MyContextListener implements ServletContextListener {

    private SSHConnection conexionssh;
    public MyContextListener() {
        super();
    }
    /**
     * @see ServletContextListener#contextInitialized(ServletContextEvent)
     */
    public void contextInitialized(ServletContextEvent arg0) {
        System.out.println("Context initialized ... !");
        try {
            conexionssh = new SSHConnection();
        } catch (Throwable e) {
            e.printStackTrace(); // error connecting SSH server
        }
    }

    /**
     * @see ServletContextListener#contextDestroyed(ServletContextEvent)
     */
    public void contextDestroyed(ServletContextEvent arg0) {
        System.out.println("Context destroyed ... !");
        conexionssh.closeSSH(); // disconnect
    }

}

更改数据库配置文件

# 服务端口和服务名称
spring:
    datasource:
        url: jdbc:mysql://localhost:3307/cs?useUnicode=true&characterEncoding=UTF8&allowMultiQueries=true&useSSL=false&serverTimezone=UTC
        username: cs
        password: 987654321
        driver-class-name: com.mysql.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=15000
        initialSize: 5
        minIdle: 5
        maxActive: 20
        maxWait: 60000
        timeBetweenEvictionRunsMillis: 60000
        minEvictableIdleTimeMillis: 300000
        validationQuery: SELECT 1 FROM DUAL
        testWhileIdle: true
        testOnBorrow: false
        testOnReturn: false
        poolPreparedStatements: true
        maxPoolPreparedStatementPerConnectionSize: 20
        filters: stat,wall,log4j
        useGlobalDataSourceStat: true

这样使得使用本地指定的3307端口的时候会通过跳板服务器连接目标数据库，而其它端口则不会例如3306
至此完毕