监听器-启动会初始化表 学习笔记：

遇到问题：

数据库连接问题；后面采用固定写法：

解决问题

   /**c3p0取得数据源*/    public static DataSource  getDataSource() throws Exception  {        ComboPooledDataSource cpds = new ComboPooledDataSource();        cpds.setDriverClass("com.mysql.jdbc.Driver");        cpds.setJdbcUrl("jdbc:mysql://192.168.47.196:3306/test");        cpds.setUser("root");        cpds.setPassword("123456");        ComboPooledDataSource datasSource = cpds;        return datasSource;    }

监听器配置：

import java.util.Timer;import java.util.TimerTask;import java.util.UUID;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import cn.vote.dao.SystemDao;public class SystemListener implements ServletContextListener {    @Override    public void contextInitialized(ServletContextEvent sce) {        SystemDao systemDao = new SystemDao();        try {            systemDao.createTable("liwen");            systemDao.init();        } catch (Exception e) {            e.printStackTrace();        }    }    @Override    public void contextDestroyed(ServletContextEvent sce) {        try {            SystemDao systemDao = new SystemDao();            systemDao.dropTable("liwen");        } catch (Exception e) {            e.printStackTrace();        }    }}

web.xml配置

    <listener>        <listener-class>cn.xijie.listener.SystemListener</listener-class>               </listener>

Java代码

import java.sql.SQLException;import org.apache.commons.dbutils.QueryRunner;import cn.xijie.JdbcUtil.JdbcUtil;public class SystemDao {    //删除表        public void dropTable(String tableName) throws Exception{            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 Exception{            QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());            String sql = "CREATE TABLE IF NOT EXISTS `"+tableName+"`(`runoob_id` INT UNSIGNED AUTO_INCREMENT,`runoob_title` VARCHAR(100) NOT NULL,`runoob_author` VARCHAR(40) NOT NULL,`submission_date` DATE,PRIMARY KEY ( `runoob_id` ))ENGINE=InnoDB DEFAULT CHARSET=utf8;";            runner.update(sql);        }        //初始化数据        public void init() throws Exception{            QueryRunner runner = new QueryRunner(JdbcUtil.getDataSource());            String sql = "INSERT INTO liwen(runoob_title, runoob_author, submission_date) VALUES (\"MySQL\", \"liwen\", NOW());";            runner.update(sql);        }}