1.1.1 需求：
1.1.2 数据库设计:

1.1.3 网上商城用户模块的代码实现:(前台)1.1.3.1 编写一个通用的Servlet:
传统方式的开发一个请求对应一个Servlet:这样的话会导致一个模块的Servlet过多,导致整个项目的Servlet都会很多.能不能做一个处理?让一个模块致用一个Servlet处理请求.
注册:http://localhost:8080/store_2.0/UserServlet?method=regist
登录:http://localhost:8080/store_2.0/UserServlet?method=login
激活:http://localhost:8080/store_2.0/UserServlet?method=active
商品查询所有：http://localhost:8080/store_2.0/ProductServlet?method=findAll
商品查询某个：http://localhost:8080/store_2.0/ProductServlet?method=findById
传统:

public class UserServlet extends HttpServlet{

    public void service(HttpServletRequest req,HttpServletResponse resp){

        // 接收参数:

        String methodName = request.getParameter(“method”);

        if(“regist”.equals(methodName)){

            regist(req,resp);

        }else if(“login”.equals(methodName)){

            login(req,resp);

       }

   }

   public void regist(HttpServletRequest req,HttpServletResponse resp){

   }

   public void login(HttpServletRequest req,HttpServletResponse resp){

   }

}

public class ProductServlet extends HttpServlet{

    public void service(HttpServletRequest req,HttpServletResponse resp){

        // 接收参数:

        String methodName = request.getParameter(“method”);

        if(“findAll”.equals(methodName)){

            findAll(req,resp);

        }else if(“findById”.equals(methodName)){

            findById(req,resp);

       }

   }

   public void findAll(HttpServletRequest req,HttpServletResponse resp){

   }

   public void findById(HttpServletRequest req,HttpServletResponse resp){

   }

}

反射：

public class BaseServlet extends HttpServlet{

     public void service(HttpServletRequest req,HttpServletResponse resp){

          // http://localhost:8080/store_2.0/UserServlet?method=regist

          // http://localhost:8080/store_2.0/ProductServlet?method=findAll

          String methodName = request.getParameter(“method”);

          // 获得Class:

          Class clazz = this.getClass();

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

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

          if(path != null){

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

          }

     }

}

public class UserServlet extends BaseServlet {

   public String regist(HttpServletRequest req,HttpServletResponse resp){

         return “/login.jsp”;

   }

   public String login(HttpServletRequest req,HttpServletResponse resp){

         return “/index.jsp”;

   }

}

public class ProductServlet extends BaseServlet{

   public String findAll(HttpServletRequest req,HttpServletResponse resp){

   }

   public String findById(HttpServletRequest req,HttpServletResponse resp){

   }

}

1.1.3.2 搭建开发环境：
【步骤一】：引入开发jar包

• mysql 1
• c3p0 1
• dbutils 1
• beanutils 2
• jstl 2
• mail 1
• fileupload 2
  【步骤二】：创建包结构:
  
  【步骤三】：引入工具类和配置文件：
  【步骤四】：编写通用的Servlet: