思维导图
?自定义mvc的框架? 可以根据这个图操作
什么是mvc?
? ? index.jsp界面
? ? <a href="${pageContext.request.contextPath}/book/add">新增</a>
?? ?<a href="${pageContext.request.contextPath}/book/delete">删除</a>
?? ?<a href="${pageContext.request.contextPath}/book/edit">修改</a>
?? ?<a href="${pageContext.request.contextPath}/book/list">查询</a>
package com.hmf.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/**
?* mvc:模型层（model）?
?* 视图层：（view）?
?* 控制图（controller）
?*
?*
?*自定义mvc：
?*?? ?1.数据库处理Dao ?
?*?? ?2.servlet?
?* ? ? doget/dopost ?基本上用不上doget
?* ? ? 实体类参数接受代码（req.getparammeter（“”））
?* ? ? req.getdispather("/index.jsp").forward(req,resp);
?* ? ? resp.sendredirect("/index.jsp");
?*? ?3.jsp
?* ?
?* ?框架：反射+设计模式（极大的减少了代码量）
?* ? ? 1.通用分页指点+通用的增删改
?* ? ? 2.各层（mc）数据Dao层 控制层代码缩减
?* ? ? 3.前台代码的代码缩减
?*/
@WebServlet("/book.action")
public class BookServlet extends HttpServlet{
?? ?protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?doPost(req, resp);
?? ?}}
?运行结果
?自定义mvc原理
少数人采用这种增删改查（servlet层）
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=add">新增</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=delete">删除</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=edit">修改</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=list">查询</a>
package com.hmf.web;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/**
?* mvc:模型层（model）?
?* 视图层：（view）?
?* 控制图（controller）
?*
?*
?*自定义mvc：
?*?? ?1.数据库处理Dao ?
?*?? ?2.servlet?
?* ? ? doget/dopost ?基本上用不上doget
?* ? ? 实体类参数接受代码（req.getparammeter（“”））
?* ? ? req.getdispather("/index.jsp").forward(req,resp);
?* ? ? resp.sendredirect("/index.jsp");
?* ?3.jsp
?* ?
?* ?框架：反射+设计模式（极大的减少了代码量）
?* ? ? 1.通用分页指点+通用的增删改
?* ? ? 2.各层（mc）数据Dao层 控制层代码缩减
?* ? ? 3.前台代码的代码缩减
?*/
@WebServlet("/book.action")
public class BookServlet extends HttpServlet{
?? ?protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?doPost(req, resp);
?? ?}
?? ?
?? ?
?? ?protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {?? ??? ? * 优点：代码减少 ?有之前的四个类变成一个类
?? ??? ? * 缺点：每一次新增一个方法，都要改变原有的逻辑? ? ? ? ? ? ? ? 一般修改时都需要数据回显load
<a href="${pageContext.request.contextPath}/book.action?methodName=load">回显</a>
?? ??? ?String methodName = req.getParameter("methodName");
?? ??? ?if("add".equals(methodName)) {
?? ??? ??? ?add(req,resp);
?? ??? ?}else if("edit".equals(methodName)) {
?? ??? ??? ?edit(req,resp);
?? ??? ?}else if("delete".equals(methodName)) {
?? ??? ??? ?delete(req,resp);
?? ??? ?}else if("list".equals(methodName)) {
?? ??? ??? ?list(req,resp);
?? ??? ?}
?? ?}
?? ?private void delete(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.delete()...");
?? ?}
?? ?private void list(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.list()...");
?? ?}
?? ?private void edit(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.edit()...");
?? ?}
?? ?private void add(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.add()...");
?? ?}
}
?
?
package com.hmf.web;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;/**
?* mvc:模型层（model）?
?* 视图层：（view）?
?* 控制图（controller）
?*
?*
?*自定义mvc：
?*?? ?1.数据库处理Dao ?
?*?? ?2.servlet?
?* ? ? doget/dopost ?基本上用不上doget
?* ? ? 实体类参数接受代码（req.getparammeter（“”））
?* ? ? req.getdispather("/index.jsp").forward(req,resp);
?* ? ? resp.sendredirect("/index.jsp");
?* ?3.jsp
?* ?
?* ?框架：反射+设计模式（极大的减少了代码量）
?* ? ? 1.通用分页指点+通用的增删改
?* ? ? 2.各层（mc）数据Dao层 控制层代码缩减
?* ? ? 3.前台代码的代码缩减
?*/
@WebServlet("/book.action")
public class BookServlet extends HttpServlet{
?? ?protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?doPost(req, resp);
?? ?}
?? ?
?? ?
?? ?protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
?? ??? ?/**
?? ??? ? * 优点：代码减少 ?有之前的四个类变成一个类
?? ??? ? *?
?? ??? ? * 缺点：每一次新增一个方法，都要改变原有的逻辑?? ??? ? * 结论：
?? ??? ? * ?? ?反射可以修复上面改动代码才能解决需求问题的缺陷
?? ??? ? * ?? ?反射代码 ?相当于中央控制器 ?并不是直接处理浏览请求
?? ??? ? * ?? ??? ??? ?处理浏览请求的是子控制器
?? ??? ? */
?? ??? ?String methodName = req.getParameter("methodName");
?? ??? ?try {
?? ??? ??? ?Method m= this.getClass().getDeclaredMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);
?? ??? ??? ?m.setAccessible(true);
?? ??? ??? ?m.invoke(this,req, resp);
?? ??? ?} catch (Exception e) {
?? ??? ??? ?e.printStackTrace();
?? ??? ?}
?? ??? ?
?? ?
//?? ??? ?if("add".equals(methodName)) {
//?? ??? ??? ?add(req,resp);
//?? ??? ?}else if("edit".equals(methodName)) {
//?? ??? ??? ?edit(req,resp);
//?? ??? ?}else if("delete".equals(methodName)) {
//?? ??? ??? ?delete(req,resp);
//?? ??? ?}else if("list".equals(methodName)) {
//?? ??? ??? ?list(req,resp);
//?? ??? ?}else if("load".equals(methodName)) {
//?? ??? ??? ?load(req,resp);
//?? ??? ?}
?? ?}
?? ?private void load(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.load()...");
?? ?}
?? ?private void delete(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.delete()...");
?? ?}
?? ?private void list(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.list()...");
?? ?}
?? ?private void edit(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.edit()...");
?? ?}
?? ?private void add(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.add()...");
?? ?}
?? ?
?? ?private void ref(HttpServletRequest req, HttpServletResponse resp) {
?? ??? ?System.out.println("bookDao.ref()...");
?? ?}
}
?
?<%@ page language="java" contentType="text/html; charset=UTF-8"
? ? pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
大多人数开发增删改查 （servlet层）
?? ?<a href="${pageContext.request.contextPath}/book/add">新增</a>
?? ?<a href="${pageContext.request.contextPath}/book/delete">删除</a>
?? ?<a href="${pageContext.request.contextPath}/book/edit">修改</a>
?? ?<a href="${pageContext.request.contextPath}/book/list">查询</a>
<hr>
少数人采用这种增删改查（servlet层）
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=add">新增</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=delete">删除</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=edit">修改</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=list">查询</a>
<hr>
反射优化
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=load">回显</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=ref">关联查询</a>
?? ?<a href="${pageContext.request.contextPath}/book.action?methodName=other">其他查询</a>
</body>
</html>