tomcat启动出现异常处理

tomcat启动出现异常

org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesJdbc The web application [pmm] registered the JDBC driver [com.mysql.cj.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.

新增如下类即可

import lombok.extern.slf4j.Slf4j;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Enumeration;

/**
 * @author liyongfei
 */
@WebListener
@Slf4j
public class JdbcUnregisterListener implements ServletContextListener {
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        try {
            log.info("Calling MySQL AbandonedConnectionCleanupThread checkedShutdown");
            // Or com.mysql.jdbc.AbandonedConnectionCleanupThread
            Class cls = Class.forName("com.mysql.cj.jdbc.AbandonedConnectionCleanupThread");
            Method method = cls.getMethod("checkedShutdown");
            method.invoke(null);
        } catch (ClassNotFoundException | NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
            log.error("Cannot call MySQL AbandonedConnectionCleanupThread.checkedShutdown!", e);
        }

        // Now deregister JDBC drivers in this context's ClassLoader:
        // Get the webapp's ClassLoader
        ClassLoader cl = Thread.currentThread().getContextClassLoader();
        // Loop through all drivers
        Enumeration<Driver> drivers = DriverManager.getDrivers();
        while (drivers.hasMoreElements()) {
            Driver driver = drivers.nextElement();
            if (driver.getClass().getClassLoader() == cl) {
                // This driver was registered by the webapp's ClassLoader, so deregister it:
                try {
                    log.info("Deregistering JDBC driver {}", driver);
                    DriverManager.deregisterDriver(driver);
                } catch (SQLException ex) {
                    log.error("Error deregistering JDBC driver {}", driver, ex);
                }
            } else {
                // driver was not registered by the webapp's ClassLoader and may be in use elsewhere
                log.trace("Not deregistering JDBC driver {} as it does not belong to this webapp's ClassLoader", driver);
            }
        }
    }
}