测试时用的是tomcat6.0服务器:服务器一起，就会自动加载web.xml中的内容，进行时间判断，定时发送；
扩展：可以在中间加上对数据库的操作
1.先导入两个jar.包
mail.jar、activation.jar
2.配置web.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<servlet>
<servlet-name>mailsenderservlet</servlet-name><!--邮件发送程序-->
<servlet-class>com.email.MailSenderServlet</servlet-class>
<init-param>
<param-name>server</param-name><!--邮件服务器SMTP地址-->
<param-value>smtp.163.com</param-value>
</init-param>
<init-param>
<param-name>port</param-name><!--邮件服务器SMTP端口-->
<param-value>25</param-value>
</init-param>
<init-param>
<param-name>address</param-name><!--邮件地址-->
<param-value>username@163.com</param-value>
</init-param>
<init-param>
<param-name>username</param-name><!--邮件账号-->
<param-value>username</param-value>
</init-param>
<init-param>
<param-name>password</param-name><!--密码-->
<param-value>******</param-value>
&nbs
