1. 什么是MVC
MVC全名是Model View Controller，是模型(model)－视图(view)－控制器(controller)的缩写， 它是一种软件设计典范，用一种业务逻辑、数据、界面显示分离的方法组织代码
Model1 jsp+jdbc
Model2 ->MVC
2. 自定义MVC工作原理图
工具类：
ActionModel.java
ConfigModel.java
ConfigModelFactory.java
ForwardModel.java
mvc.xml
3. 通过XML对自定义mvc框架进行增强
3.1将子控制器信息动态配置到mvc.xml中
DispatcherServlet.java
package com.huang.framework;import java.io.IOException;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.util.HashMap;import java.util.Map;import java.util.Map.Entry;import java.util.Set;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.beanutils.BeanUtils;/** * 中央控制器 * 作用：接收请求，通过请求寻找处理请求的对应的自控器 * @author Admin * */public class DispatcherServlet extends HttpServlet { private static final long serialVersionUID = 7565258196310251777L;// private Map actionMap=new HashMap<>();// 在configModel对象中包含了所有的子控制器 private ConfigModel configModel; public void init() {// actionMap.put("/addCal", new AddCalAction());// actionMap.put("/delCal", new DelCalAction());// actionMap.put("/cheCal", new CheCalAction());// actionMap.put("/chuCal", new ChuCalAction()); try { configModel=ConfigModelFactory.newInstance(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req, resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { init(); String url=req.getRequestURI(); url=url.substring(url.lastIndexOf("/"), url.lastIndexOf("."));// Action action=actionMap.get(url); ActionModel actionModel=configModel.get(url); if(actionModel==null) { throw new RuntimeException("你没有配置action标签，找不到对应的子控制器来处理浏览器发送的请求！！"); } try { Action action= (Action) Class.forName(actionModel.getType()).newInstance(); if(action instanceof ModelDrivern) { ModelDrivern mdDrivern = (ModelDrivern) action;// 此时的model的所有属性值是null的 Object model=mdDrivern.getModel(); BeanUtils.populate(model, req.getParameterMap()); // 我们可以req.getParameterMap()的值通过反射的方式将其塞进model实例// Map parameterMap=req.getParameterMap();// Set > entrySet=parameterMap.entrySet();// Class clz= model.getClass();// for (Entry entry : entrySet) {// Field field=clz.getField(entry.getKey());// field.setAccessible(true);// field.set(model, entry.getValue());// // } } String code=action.execute(req, resp); ForwardModel forwardModel= actionModel.get(code); if(forwardModel!=null) { String jspPath=forwardModel.getPath(); if("false".equals(forwardModel.getRedirect())) { //做转发的处理 req.getRequestDispatcher(jspPath).forward(req, resp); } else { resp.sendRedirect(req.getContextPath()+"/"+jspPath); } } } catch (InstantiationException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (SecurityException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InvocationTargetException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } 3.2针对mvc框架的结果码进行处理
cal.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>Insert title here
3.3将一组操作放到一个子控制器中
ActionSupport.java
package com.huang.framework;import java.io.IOException;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** * 增强版的子控制器 * 原来的子控制器只能一个用户请求 * 有时候，用户请求是多个，但是都是操作同一张表，那么原有的子控制器代码编写繁琐 * 增强版的作用 * 将一组相关的操作放到一个Action中 * @author Admin * */public class ActionSupport implements Action { @Override public String execute(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// add/del/che/chu String methodName=req.getParameter("methodName"); String code=null;// class CalAction extends ActionSupport// this在这里指的是CalAction它的一个类实例 try { Method m=this.getClass().getDeclaredMethod(methodName, HttpServletRequest.class,HttpServletResponse.class); m.setAccessible(true); code=(String) m.invoke(this, req,resp); } catch (NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { e.printStackTrace(); } return code; } } 3.4利用模型驱动接口对mvc框架进行增强
CalAction.java
package com.huang.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.huang.entity.Cal;
import com.huang.framework.ActionSupport;import com.huang.framework.ModelDrivern;public class CalAction extends ActionSupport implements ModelDrivern<Cal>{
private Cal cal=new Cal();
public String add(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // String num1=req.getParameter("num1");// String num2=req.getParameter("num2");// Cal cal=new Cal(Integer.valueOf(num1),Integer.valueOf(num2)); req.setAttribute("res", cal.getNum1() + cal.getNum2());// req.getRequestDispatcher("res.jsp").forward(req, resp); return "res"; } public String del(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // String num1=req.getParameter("num1");// String num2=req.getParameter("num2");// Cal cal=new Cal(Integer.valueOf(num1),Integer.valueOf(num2)); req.setAttribute("res", cal.getNum1() - cal.getNum2());// req.getRequestDispatcher("res.jsp").forward(req, resp); return "res"; } public String che(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // String num1=req.getParameter("num1");// String num2=req.getParameter("num2");// Cal cal=new Cal(Integer.valueOf(num1),Integer.valueOf(num2)); req.setAttribute("res", cal.getNum1() * cal.getNum2());// req.getRequestDispatcher("res.jsp").forward(req, resp); return "res"; } public String chu(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { // String num1=req.getParameter("num1");// String num2=req.getParameter("num2");// Cal cal=new Cal(Integer.valueOf(num1),Integer.valueOf(num2)); req.setAttribute("res", cal.getNum1() / cal.getNum2());// req.getRequestDispatcher("res.jsp").forward(req, resp); return "res"; }@Override
public Cal getModel() { return cal; } }3.5解决框架配置文件的冲突问题
web.xml
T226_mvc dispatcherServlet com.huang.framework.DispatcherServlet xmlPath /mvc.xml dispatcherServlet *.action