PromotionListener.java ~~~ package zyw.promotion; import com.mchange.v2.c3p0.ComboPooledDataSource; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanListHandler; import zyw.bean.Product; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; import javax.servlet.annotation.WebListener; import java.math.BigDecimal; import java.sql.SQLException; import java.util.Date; import java.util.List; import java.util.Timer; import java.util.TimerTask; @WebListener() public class PromotionListener implements ServletContextListener{ public PromotionListener() { } public void contextInitialized(ServletContextEvent sce) { Timer timer=new Timer();//創建定時器 //1.要執行的任務2.第一次執行的時間3.間隔的時長 timer.scheduleAtFixedRate(new TimerTask() { @Override public void run() { try {//快捷鍵，選中代碼塊，Ctrl+Art+t ComboPooledDataSource comboPooledDataSource=new ComboPooledDataSource(); QueryRunner queryRunner=new QueryRunner(comboPooledDataSource); String sql="select * from product"; List<Product> productList = queryRunner.query(sql, new BeanListHandler<Product>(Product.class)); // 獲取商品信息后遍歷 商品 根據不同的種類，修改不同的價格 if (productList!=null&&productList.size()>0){ for (Product product : productList) { if (product.getC_id()==1){ //數碼產品 BigDecimal p_price = product.getP_price(); //減100元 BigDecimal temp=new BigDecimal(100); p_price=p_price.subtract(temp); //將修改好的價格設置給對象 product.setP_price(p_price); System.out.println(product.getP_name()+"現在打折促銷啦，只要"+ product.getP_price()+"就可以拿回家啦！"); }else { //數碼產品 BigDecimal p_price = product.getP_price(); //減100元 BigDecimal temp=new BigDecimal(10); p_price=p_price.subtract(temp); //將修改好的價格設置給對象 product.setP_price(p_price); System.out.println(product.getP_name()+"現在打折促銷啦，只要"+ product.getP_price()+"就可以拿回家啦！"); } } } } catch (SQLException e) { e.printStackTrace(); } } }, new Date(), 1000*20); } public void contextDestroyed(ServletContextEvent sce) { } } ~~~ Product.java ~~~ package zyw.bean; import java.math.BigDecimal; public class Product { private int p_id; private String p_name; private BigDecimal p_price; private String p_image; private int c_id; @Override public String toString() { return "Product{" + "p_id=" + p_id + ", p_name='" + p_name + '\'' + ", p_price=" + p_price + ", p_image='" + p_image + '\'' + ", c_id=" + c_id + '}'; } public Product() { } public int getP_id() { return p_id; } public void setP_id(int p_id) { this.p_id = p_id; } public String getP_name() { return p_name; } public void setP_name(String p_name) { this.p_name = p_name; } public BigDecimal getP_price() { return p_price; } public void setP_price(BigDecimal p_price) { this.p_price = p_price; } public String getP_image() { return p_image; } public void setP_image(String p_image) { this.p_image = p_image; } public int getC_id() { return c_id; } public void setC_id(int c_id) { this.c_id = c_id; } } ~~~ c3p0-config.xml放在src目錄下 ~~~ <?xml version="1.0" encoding="utf-8" ?> <c3p0-config> <!-- 默認配置，如果沒有指定則使用這個配置 --> <default-config> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql://122.14.200.136:3306/javadb</property> <property name="user">root</property> <property name="password">6a133f0024</property> <!-- 初始化池大小 --> <property name="initialPoolSize">5</property> <!-- 最大空閑時間 --> <property name="maxIdleTime">30</property> <!-- 最多有多少個連接 --> <property name="maxPoolSize">10</property> <!-- 最少幾個連接 --> <property name="minPoolSize">5</property> <!-- 每次最多可以執行多少個批處理語句 --> <property name="maxStatements">50</property> </default-config> <!-- 命名的配置 --> <named-config name="51zixue"><!--這里是設置配置文件的名字--> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql://122.14.200.136:3306/javadb</property> <property name="user">root</property><!--mysql的登陸名--> <property name="password">6a133f0024</property><!--如果沒密碼就可以設置成<property name="password"></property>--> <property name="acquireIncrement">5</property><!-- 如果池中數據連接不夠時一次增長多少個 --> <property name="initialPoolSize">10</property> <property name="minPoolSize">5</property> <property name="maxPoolSize">15</property> <property name="maxStatements">0</property> <property name="maxStatementsPerConnection">5</property> <!-- he's important, but there's only one of him --> </named-config> </c3p0-config> ~~~ jar包  數據庫   結果，每隔20秒刷新一次