请问编写学生选课系统servlet出问题如何解决？

编写学生选课系统，使用mysql数据库，连接池访问，最后布置到tomcat上

结果始终404

img

proxool.property文件

jdbc-1.proxool.alias=test
jdbc-1.proxool.driver-class=com.mysql.jdbc.Driver
jdbc-1.proxool.driver-url=jdbc:mysql://127.0.0.1:3306?useUnicode=true&characterEncoding=utf8
#jdbc-1.proxool.driver-class=oracle.jdbc.OracleDriver
#jdbc-1.proxool.driver-url=jdbc:oracle:thin:@127.0.0.1:1521:XE
jdbc-1.user=root
jdbc-1.password=P@ssword404.
#最大连接数
jdbc-1.proxool.maximum-connection-count=100
jdbc-1.proxool.minimum-connection-count=5
jdbc-1.proxool.prototype-count=4
jdbc-1.proxool.verbose=true
jdbc-1.proxool.statistics=10s,1m,1d
jdbc-1.proxool.statistics-log-level=error


#web_sscs?useUnicode=true&characterEncoding=utf8

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
  <display-name>web_sscs</display-name>
  
  <!-- Web项目中配置proxool，并自动加载 -->
      <servlet>
     <servlet-name>ServletConfigurator</servlet-name>
     <servlet-class>
     org.logicalcobwebs.proxool.configuration.ServletConfigurator
     </servlet-class>
     <init-param>
      <param-name>propertyFile</param-name>
      <param-value>WEB-INF/classes/proxool.properties</param-value>
     </init-param>
     <load-on-startup>1</load-on-startup>
    </servlet>
  

  
  
  <welcome-file-list>

    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
</web-app>