The web inserts a record into the database every 5 seconds-Learn notes

Systemlistener

Import Java.util.timer;import java.util.timertask;import java.util.uuid;import javax.servlet.ServletContextEvent; Import Javax.servlet.servletcontextlistener;import Cn.itcast.web.dao.systemdao;public class SystemListener    Implements Servletcontextlistener {Private Timer timer = new timer ();            public void contextinitialized (Servletcontextevent sce) {try {Systemdao Systemdao = new Systemdao ();            Systemdao.createtable ("Systeminit");        Timer.schedule (New Systemtask (), 0,5*1000); } catch (Exception e) {}} public void contextdestroyed (Servletcontextevent sce) {try {S            Ystemdao Systemdao = new Systemdao ();            Systemdao.droptable ("Systeminit");        Abort timer timer.cancel ();            } catch (Exception e) {}}}//Task Class class Systemtask extends timertask{public void run () {try {            Systemdao Systemdao = new Systemdao (); Systemdao.init ("Systeminit", Uuid.randoMuuid (). toString ()); } catch (Exception e) {}}}

Table

*/import java.sql.SQLException;import org.apache.commons.dbutils.QueryRunner;import cn.itcast.web.util.JdbcUtil;public class SystemDao {    //删除表    public void dropTable(String tableName) throws SQLException{        QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());        String sql = "drop table if exists " + tableName;        runner.update(sql);    }    //创建表    public void createTable(String tableName) throws SQLException{        QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());        String sql = "create table if not exists "+tableName+"(id varchar(40) primary key,curr_time timestamp not null)";        runner.update(sql);    }    //初始化数据    public void init(String tableName,String id) throws SQLException{        QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());        String sql = "insert into "+tableName+"(id) values(?)";        runner.update(sql,id);    }}

Web. XML configuration

The web inserts a record into the database every 5 seconds-Learn notes