目录
一，MVC简介1.什么是mvc
二，最初的增删改查
三，反射版的增删改查
四，自定义MVC工作原理图编辑
五，自定义mvc后台代码实现中央控制器：
铁子们今天分享的是自定义mvc先看思维导图
一，MVC简介
1.什么是mvc
MVC(Model View Controller)是一种软件设计的框架模式，它采用模型(Model)-视图(View)-控制器(controller)的方法把业务逻辑、数据与界面显示分离。把众多的业务逻辑聚集到一个部件里面，当然这种比较官方的解释是不能让我们足够清晰的理解什么是MVC的。用通俗的话来讲，MVC的理念就是把数据处理、数据展示(界面)和程序/用户的交互三者分离开的一种编程模式
2.mvc的作用
MVC 属架构于模式的一种，所谓架构就是如何设计一个程序的结构。MVC 将程序结构划分为三层，每一层都对外提供了可供上层调用的接口，既能维系三层之间的联系，也能保持相对的独立性
二，最初的增删改查
增加
package com.tsq.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;
@WebServlet("/book/add")
public class AddBookServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("处理书籍的增加业务调用bookbiz");
}
}
删除
package com.tsq.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;
@WebServlet("/Book/del")
public class DelBookServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("处理书籍的删除业务调用bookbiz");
}
}
修改
package com.tsq.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;
@WebServlet("/Book/edit")
public class EditBookServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("处理书籍的修改业务调用bookbiz");
}
}
查询
package com.tsq.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;
@WebServlet("/Book/list")
public class ListBookServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("处理书籍的 编辑业务调用bookbiz");
}
}
存在的问题：
1.关于单个实体/表操作场景越多，需要新建的类也就越多，造成了项目中的数量过于庞大
2.当新增了业务，除了要添加该业务对应的方法load，同时还要改动源代码
3.反射相关代码，在每一个实体类对应的servlet中存在
4.每一个servlet中都有doget，dopost方法
三，反射版的增删改查
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
Insert title here
目前做增删改查方法
增加
删除
修改
查看
类数量过多优化
增加
删除
修改
查看
查看
5
package com.tsq.web;
import java.io.IOException;
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;
@WebServlet("/book.action")
public class BookServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 为了区分当前请求来的目的，增删改查目的，就从前台要调用的方法名传到后台
String methodName = request.getParameter("methodName");
// methodName可以能是add/del/edit/list/load/xxx/yyy/aaa...
// 前台传递什么方法 就调用当前的对应方法
try {
Method m = this.getClass()//Bookservelt.class
.getDeclaredMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);
m.setAccessible(true);
//调用当前实例类 的 methodName 方法
m.invoke(this, request,response);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// if("add".equals(methodName)) {
// add(request,response);
// }else if("del".equals(methodName)) {
// del(request,response);
// }else if("edit".equals(methodName)) {
// edit(request,response);
// }else if("list".equals(methodName)) {
// list(request,response);
// }else if("list".equals(methodName)) {
// load(request,response);
// }
}
private void list(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 list 方法");
}
private void load(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 list 方法");
}
private void edit(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 edit 方法");
}
private void del(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 del 方法");
}
private void add(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 add 方法");
}
}
四，自定义MVC工作原理图
中央控制器：
package com.tsq.framework;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.tsq.web.BookAction;
@WebServlet("*.action")
public class DispatcherServlet extends HttpServlet{
private Map actions = new HashMap();
//程序启动时，只会加载一次
@Override
public void init() throws ServletException {
actions.put("/book", new BookAction());
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// TODO Auto-generated method stub
super.doGet(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//http://localhost:8080/mvc/book.action?methodName=list
String uri = req.getRequestURI();
// 要拿到/book,就是最后一个/到最后一个，的为止
uri = uri.substring(uri.lastIndexOf("/")
, uri.lastIndexOf("."));
Action action = actions.get(uri);
action.execute(req, resp);
}
}
子控制器
package com.tsq.framework;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public interface Action {
void execute(HttpServletRequest request,HttpServletResponse response);
}
实现子控制器接口
package com.tsq.framework;
import java.lang.reflect.Method;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ActionSupport implements Action{
@Override
public void execute(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
String methodName = request.getParameter("methodName");
try {
Method m = this.getClass()//Bookservelt.class
.getDeclaredMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);
m.setAccessible(true);
//调用当前实例类 的 methodName 方法
m.invoke(this, request,response);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
继承子控制器实现的接口
package com.tsq.web;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.tsq.framework.Action;
import com.tsq.framework.ActionSupport;
public class BookAction extends ActionSupport{
private void list(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 list 方法");
}
private void load(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 list 方法");
}
private void edit(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 edit 方法");
}
private void del(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 del 方法");
}
private void add(HttpServletRequest request, HttpServletResponse response) {
// TODO Auto-generated method stub
System.out.println("在同一个servlet中调用 add 方法");
}}
