传统的方式：
* 一个请求对应一个Servlet.
* 能不能一个模块对应一个Servlet.

一个模块对应一个Servlet:
<a href=”/UserServlet?method=add”>添加</a>
<a href=”/UserServlet?method=update”>修改</a>
<a href=”/UserServlet?method=delete”>删除</a>

public class UserServlet extends HttpServlet{

   public void service(HttpServletRequest req,HttpServletResponse resp){
           String method = req.getParameter(“method”);
           if(“add”.equals(method)){
               add(req,resp);
           }else if(“update”.equals(method)){
               update(req,resp);
           }
   }

   public void add(HttpServletRequest req,HttpServletResponse resp){
   
   }

   public void update(HttpServletRequest req,HttpServletResponse resp){
   
   }

}

改进以后：
public class BaseServlet extends HttpServlet{
   public void service(HttpServletRequest req,HttpServletResponse resp){
           String methodName = req.getParameter(“method”);
           // 反射:
           Class clazz = this.getClass(); // 指代的是子类的对象.
           Method method = clazz.getMethod(methodName ,HttpServletRequest.class,HttpServletResponse,class);
           method.invoke(this,req,resp);
   }

}


public class UserServlet extends BaseServlet{

   public void add(HttpServletRequest req,HttpServletResponse resp){
   
   }

   public void update(HttpServletRequest req,HttpServletResponse resp){
   
   }

}

public class A{
   public A(){
      System.out.println(this.getClass());
   }
}

public class B extends A{
    Public B(){

    }
}

public class Test{
   Public static void main(String[] args){
       B b = new B();
   }
}

【代码实现】

public class BaseServlet extends HttpServlet{

 

    @Override

    // http://loacalhost:8080/store/UserServlet?method=add

    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // 处理Post请求的乱码

        req.setCharacterEncoding("UTF-8");

        // 接收参数:

        String methodName = req.getParameter("method");

        // 反射获得类的字节码.

        Class clazz = this.getClass();

        // 获得正在执行的类的指定名称的方法

        try {

            Method method = clazz.getMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);

            // 让这个方法执行:

            String path = (String) method.invoke(this, req,resp);

            if(path != null){

                req.getRequestDispatcher(path).forward(req, resp);

            }

        } catch (Exception e) {

            e.printStackTrace();

        }

    }

 

}

【创建一个WEB工程】

【创建包结构】

【引入相应的jar包】

    * mysql驱动          1

    * dbutils            1

    * c3p0连接池         1

    * beanutils          2

    * JSTL               2

    * 文件上传            2

    * 发送邮件            1

【创建数据库和表】

CREATE TABLE `user` (

  `uid` varchar(32) NOT NULL,

  `username` varchar(20) DEFAULT NULL,

  `password` varchar(20) DEFAULT NULL,

  `name` varchar(20) DEFAULT NULL,

  `email` varchar(30) DEFAULT NULL,

  `telephone` varchar(20) DEFAULT NULL,

  `birthday` varchar(20) DEFAULT NULL,

  `sex` varchar(10) DEFAULT NULL,

  `state` int(11) DEFAULT NULL,

  `code` varchar(64) DEFAULT NULL,

  PRIMARY KEY (`uid`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;