【SSH进阶之路】一步步重构MVC实现Struts框架——封装业务逻辑和跳转路径(四)
来源:互联网 发布:未授权域名 编辑:程序博客网 时间:2024/06/05 08:02
目录:
【SSH进阶之路】Struts基本原理 + 实现简单登录(二)
【SSH进阶之路】一步步重构MVC实现Struts框架——从一个简单MVC开始(三)
【SSH进阶之路】一步步重构MVC实现Struts框架——封装业务逻辑和跳转路径(四)
【SSH进阶之路】一步步重构MVC实现Struts框架——彻底去掉逻辑判断(五)
【SSH进阶之路】一步步重构MVC实现Struts框架——完善转向页面,大功告成(六)
Struts的第二篇博客【SSH进阶之路】Struts基本原理 + 实现简单登录(二),我们介绍了MVC和Struts的基本理论,上篇博客【SSH进阶之路】一步步重构MVC实现Struts框架——从一个简单MVC开始(三),我们实现了一个MVC模型,这篇博客我们解决一下上篇博客留下的第一个问题:封装业务逻辑和跳转路径。
我们先回顾一下上篇博客中的TestServlet的代码:
- package com.liang.servlet;
-
- import java.io.IOException;
- import java.util.List;
-
- import javax.servlet.ServletException;
- import javax.servlet.http.HttpServlet;
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
-
-
-
-
- public class TestServlet extends HttpServlet {
-
- @Override
- protected void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
-
- String reqeuestURI = request.getRequestURI();
- System.out.println(reqeuestURI);
-
- String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));
- System.out.println(path);
-
- String username = request.getParameter("username");
-
- UserManager userManager = new UserManager();
-
- String forward ="";
-
-
- if("/servlet/addUser".equals(path)){
-
- userManager.add(username);
- forward ="/add_success.jsp";
-
- }else if("/servlet/delUser".equals(path)){
-
- userManager.del(username);
- forward ="/del_success.jsp";
-
- }else if("/servlet/modifyUser".equals(path)){
-
- userManager.modify(username);
- forward ="/modify_success.jsp";
-
- }else if("/servlet/queryUser".equals(path)){
-
- List userList = userManager.query(username);
- request.setAttribute("userList", userList);
- forward ="/query_success.jsp";
- }else{
- throw new RuntimeException("请求失败");
- }
-
- request.getRequestDispatcher(forward).forward(request, response);
- }
-
- @Override
- protected void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doGet(request,response);
- }
-
- }
从TestServlet中我们发现,它就是一个简单的Servlet,它是Struts的前端控制器,负责把所有的URL截取下来,通过IF语句根据URL的不同执行相关的功能,并且添加,删除,修改和查询各自有各自的业务逻辑和跳转路径,我们可以各自的业务逻辑和跳转路径封装成不同的类,并抽象出一个公共接口,如下所示:
下面,我们看一下接口和实现类的代码:
接口Action
- package com.liang.servlet;
-
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- public interface Action {
-
- public String execute(HttpServletRequest req, HttpServletResponse resp)
- throws Exception;
- }
添加用户AddUserAction
- package com.liang.servlet;
-
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- public class AddUserAction implements Action {
-
- @Override
- public String execute(HttpServletRequest req, HttpServletResponse resp)
- throws Exception {
-
- String username = req.getParameter("username");
-
- UserManager userManager = new UserManager();
-
- userManager.add(username);
-
- return "/add_success.jsp";
- }
-
- }
删除用户DelUserAction- package com.liang.servlet;
-
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- public class DelUserAction implements Action {
-
- @Override
- public String execute(HttpServletRequest req, HttpServletResponse resp)
- throws Exception {
- <span style="white-space:pre"> </span>
- String username = req.getParameter("username");
-
- UserManager userManager = new UserManager();
-
- userManager.del(username);
-
- return "/del_success.jsp";
- }
-
- }
修改用户ModifyUserAction- package com.liang.servlet;
-
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- public class ModifyUserAction implements Action {
-
- @Override
- public String execute(HttpServletRequest req, HttpServletResponse resp)
- throws Exception {
-
- String username = req.getParameter("username");
-
-
- UserManager userManager = new UserManager();
-
- userManager.modify(username);
-
- return "/modify_success.jsp";
- }
-
- }
查询用户QueryUserAction- package com.liang.servlet;
-
- import java.util.List;
-
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- public class QueryUserAction implements Action {
-
- @Override
- public String execute(HttpServletRequest req, HttpServletResponse resp)
- throws Exception {
-
- String username = req.getParameter("username");
-
-
- UserManager userManager = new UserManager();
-
- List userList = userManager.query(username);
- req.setAttribute("userList", userList);
-
- userManager.query(username);
-
- return "/query_success.jsp";
- }
-
- }
我们再对比看一下我们封装之后的TestServlet- package com.liang.servlet;
-
- import java.io.IOException;
- import javax.servlet.ServletException;
- import javax.servlet.http.HttpServlet;
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- import com.liang.action.Action;
- import com.liang.action.AddUserAction;
- import com.liang.action.DelUserAction;
- import com.liang.action.ModifyUserAction;
- import com.liang.action.QueryUserAction;
-
-
-
-
-
- public class TestServlet extends HttpServlet {
-
- @Override
- protected void doGet(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
-
- String reqeuestURI = request.getRequestURI();
- System.out.println(reqeuestURI);
-
- String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));
- System.out.println(path);
-
- Action action = null;
-
- if ("/servlet/addUser".equals(path)) {
- action = new AddUserAction();
-
- }else if ("/servlet/delUser".equals(path)) {
- action = new DelUserAction();
-
- }else if ("/servlet/modifyUser".equals(path)) {
- action = new ModifyUserAction();
-
- }else if ("/servlet/queryUser".equals(path)) {
- action = new QueryUserAction();
- }else {
- throw new RuntimeException("请求失败");
- }
- String forward = null;
-
- try {
- forward = action.execute(request, response);
- } catch (Exception e) {
- e.printStackTrace();
- }
-
- request.getRequestDispatcher(forward).forward(request, response);
- }
-
- @Override
- protected void doPost(HttpServletRequest request, HttpServletResponse response)
- throws ServletException, IOException {
- doGet(request,response);
- }
-
- }
通过对比,我们可以发现简单了很多,但是实现的道理基本一样,仍然是将path截取出来,做相应的判断,进入对应的分支,New一个刚写的Action,New谁调谁,但是此时仅仅是完成了功能,系统并不灵活,IF...ELSE并没有去掉,扩展性不好,不能适用需求。
下篇博客【SSH进阶之路】一步步重构MVC实现Struts框架——彻底去掉判断逻辑(五),我们解决第二个问题:IF...ElSE的问题。
源码下载
0 0