思路

写一个baseServlet继承httpServlet，重写service方法，在service方法中对前端的url
进行解析，通过反射调用方法，执行module层的逻辑。

我们只需要写servlet去继承baseServlet，不需要继承httpServlet，重写里面的方法。

流程如下：

• 前端发送一个请求http://localhost:8080/user?method=login
• 经过service方法将请求进行解析，获得method = login，通过反射调用login方法，实现请求的分发
• 在login中实现登录的业务逻辑
• login方法结束后，解析返回的字符串，判断走重定向还是请求转发

代码

baseServlet类：
中央控制器，负责调度分配请求

public class BaseServlet extends HttpServlet{
    
      
	@Override
	protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
      
		// TODO Auto-generated method stub
		try {
    
      
			request.setCharacterEncoding("utf-8");
			response.setCharacterEncoding("utf-8");
			//获取需要被执行前的方法
			String methodName=request.getParameter("method");
			//获取当前对象对应的class对象
			Class clz=this.getClass();
			Method method= clz.getMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);
			
			Object obj= method.invoke(this,request,response);
			if(Objects.nonNull(obj)){
    
      
				String page=obj.toString();
				if(page.startsWith("redirect:")){
    
      
					page=page.substring("redirect:".length());
					
					response.sendRedirect(page.trim());
				}else{
    
      
					request.getRequestDispatcher(page.trim()).forward(request, response);
				}
			}
		} catch (NoSuchMethodException | SecurityException e) {
    
      
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
    
      
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalArgumentException e) {
    
      
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InvocationTargetException e) {
    
      
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}

}

UserServlet类：
继承baseServlet,写业务逻辑

@WebServlet("/user.do")
@MultipartConfig
public class UserServlet extends BaseServlet {
    
      
	private static final long serialVersionUID = 1L;

    public String login(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException{
    
      
    	System.out.println("123");
    	String uname=request.getParameter("username");
    	String password=request.getParameter("password");
    	
    	User user=new User();
    	user.setUname(uname);
    	user.setPassword(password);
    	Model model=ServiceFactory.newInstance().getUserService().login(user);
    	String r= request.getParameter("remerber");
    	if(model.isSuccess()){
    
      
    		request.getSession().setAttribute("user",model.getData());
    		if(Objects.equals("1",r)){
    
      
    			user=(User)model.getData();
    			user.setPassword(password);
    			String json=JSON.toJSONString(user);
    			json=URLEncoder.encode(json,"utf-8");
    			Cookie cookie=new Cookie("user",json);
    			cookie.setMaxAge(60*60*24*30);
    			response.addCookie(cookie);
    		}
    		return "redirect:topic.do?method=mytopic";
    	}else{
    
      
    		request.setAttribute("msg",model.getMsg());
    		return "login.jsp";
    	}
    }
    
    public String logout(HttpServletRequest request,HttpServletResponse response){
    
      
    	HttpSession s=request.getSession(false);
    	s.invalidate();
    	return "login.jsp";
    }
}