目錄：

? ? ??【SSH進(jìn)階之路】Struts基本原理 + 實(shí)現(xiàn)簡(jiǎn)單登錄（二）

? ? ? 【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——從一個(gè)簡(jiǎn)單MVC開(kāi)始（三）

? ? ? 【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——封裝業(yè)務(wù)邏輯和跳轉(zhuǎn)路徑（四）

? ? ??【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——徹底去掉邏輯判斷（五）

? ? ? 【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——完善轉(zhuǎn)向頁(yè)面，大功告成（六）

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? ? ? ?Struts的第二篇博客【SSH進(jìn)階之路】Struts基本原理 + 實(shí)現(xiàn)簡(jiǎn)單登錄（二），我們介紹了MVC和Struts的基本理論，上篇博客【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——從一個(gè)簡(jiǎn)單MVC開(kāi)始（三），我們實(shí)現(xiàn)了一個(gè)MVC模型，這篇博客我們解決一下上篇博客留下的第一個(gè)問(wèn)題：封裝業(yè)務(wù)邏輯和跳轉(zhuǎn)路徑。

? ? ? ?我們先回顧一下上篇博客中的TestServlet的代碼：

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; /*** 使用servlet做相關(guān)的控制，轉(zhuǎn)向多個(gè)（V）視圖* @author liang**/ public class TestServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//取得訪(fǎng)問(wèn)的URIString reqeuestURI = request.getRequestURI();System.out.println(reqeuestURI);//截取URI，獲得路徑String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));System.out.println(path);//獲得表單數(shù)據(jù)String username = request.getParameter("username");UserManager userManager = new UserManager();String forward ="";//根據(jù)url執(zhí)行相關(guān)的功能//等于添加，調(diào)用添加方法，添加成功轉(zhuǎn)到添加頁(yè)面if("/servlet/addUser".equals(path)){//調(diào)用添加的業(yè)務(wù)邏輯userManager.add(username);forward ="/add_success.jsp";//刪除，調(diào)用刪除方法，刪除成功轉(zhuǎn)到刪除}else if("/servlet/delUser".equals(path)){//調(diào)用刪除的業(yè)務(wù)邏輯userManager.del(username);forward ="/del_success.jsp";//修改，調(diào)用修改方法，修改成功轉(zhuǎn)到修改頁(yè)面}else if("/servlet/modifyUser".equals(path)){//調(diào)用修改的業(yè)務(wù)邏輯userManager.modify(username);forward ="/modify_success.jsp";//查詢(xún)，調(diào)用查詢(xún)方法，查詢(xún)成功轉(zhuǎn)到查詢(xún)成功頁(yè)面}else if("/servlet/queryUser".equals(path)){//調(diào)用查詢(xún)的業(yè)務(wù)邏輯List userList = userManager.query(username);request.setAttribute("userList", userList);forward ="/query_success.jsp";}else{throw new RuntimeException("請(qǐng)求失敗");}//統(tǒng)一完成轉(zhuǎn)向request.getRequestDispatcher(forward).forward(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request,response);}}

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? ? ? ?從TestServlet中我們發(fā)現(xiàn)，它就是一個(gè)簡(jiǎn)單的Servlet，它是Struts的前端控制器，負(fù)責(zé)把所有的URL截取下來(lái)，通過(guò)IF語(yǔ)句根據(jù)URL的不同執(zhí)行相關(guān)的功能，并且添加，刪除，修改和查詢(xún)各自有各自的業(yè)務(wù)邏輯和跳轉(zhuǎn)路徑，我們可以各自的業(yè)務(wù)邏輯和跳轉(zhuǎn)路徑封裝成不同的類(lèi)，并抽象出一個(gè)公共接口，如下所示：

下面，我們看一下接口和實(shí)現(xiàn)類(lèi)的代碼：

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; }

添加用戶(hù)AddUserAction

package com.liang.servlet;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class AddUserAction implements Action {@Overridepublic String execute(HttpServletRequest req, HttpServletResponse resp)throws Exception {//獲取參數(shù)String username = req.getParameter("username");UserManager userManager = new UserManager();//調(diào)用業(yè)務(wù)邏輯userManager.add(username);//返回跳轉(zhuǎn)頁(yè)面return "/add_success.jsp";}}
刪除用戶(hù)DelUserAction

package com.liang.servlet;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class DelUserAction implements Action {@Overridepublic String execute(HttpServletRequest req, HttpServletResponse resp)throws Exception { <span style="white-space:pre"> </span>//獲取參數(shù)String username = req.getParameter("username");UserManager userManager = new UserManager();//調(diào)用業(yè)務(wù)邏輯userManager.del(username);//返回跳轉(zhuǎn)頁(yè)面return "/del_success.jsp";}}
修改用戶(hù)ModifyUserAction

package com.liang.servlet;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class ModifyUserAction implements Action {@Overridepublic String execute(HttpServletRequest req, HttpServletResponse resp)throws Exception {//獲取參數(shù)String username = req.getParameter("username");//調(diào)用業(yè)務(wù)邏輯UserManager userManager = new UserManager();userManager.modify(username);//返回跳轉(zhuǎn)頁(yè)面return "/modify_success.jsp";}}
查詢(xún)用戶(hù)QueryUserAction

package com.liang.servlet;import java.util.List;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;public class QueryUserAction implements Action {@Overridepublic String execute(HttpServletRequest req, HttpServletResponse resp)throws Exception {//獲取參數(shù)String username = req.getParameter("username");//調(diào)用業(yè)務(wù)邏輯UserManager userManager = new UserManager();List userList = userManager.query(username);req.setAttribute("userList", userList);userManager.query(username);//返回跳轉(zhuǎn)頁(yè)面return "/query_success.jsp";}}
我們?cè)賹?duì)比看一下我們封裝之后的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; /*** 使用servlet做相關(guān)的控制，轉(zhuǎn)向多個(gè)（V）視圖* @author liang**/ public class TestServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//取得訪(fǎng)問(wèn)的URIString reqeuestURI = request.getRequestURI();System.out.println(reqeuestURI);//截取URI，獲得路徑String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));System.out.println(path);Action action = null;//等于添加，調(diào)用AddUserActionif ("/servlet/addUser".equals(path)) {action = new AddUserAction();//等于刪除，調(diào)用DelUserAction}else if ("/servlet/delUser".equals(path)) {action = new DelUserAction();//等于修改，調(diào)用ModifyUserAction}else if ("/servlet/modifyUser".equals(path)) {action = new ModifyUserAction();//等于查詢(xún)，調(diào)用QueryUserAction}else if ("/servlet/queryUser".equals(path)) {action = new QueryUserAction();}else {throw new RuntimeException("請(qǐng)求失敗");}String forward = null;//返回不同的轉(zhuǎn)向頁(yè)面try {forward = action.execute(request, response);} catch (Exception e) {e.printStackTrace();}//根據(jù)路徑,統(tǒng)一完成轉(zhuǎn)向request.getRequestDispatcher(forward).forward(request, response);}@Overrideprotected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request,response);}}
? ? ? 通過(guò)對(duì)比，我們可以發(fā)現(xiàn)簡(jiǎn)單了很多，但是實(shí)現(xiàn)的道理基本一樣，仍然是將path截取出來(lái)，做相應(yīng)的判斷，進(jìn)入對(duì)應(yīng)的分支，New一個(gè)剛寫(xiě)的Action，New誰(shuí)調(diào)誰(shuí)，但是此時(shí)僅僅是完成了功能，系統(tǒng)并不靈活，IF...ELSE并沒(méi)有去掉，擴(kuò)展性不好，不能適用需求。

? ? ? 下篇博客【SSH進(jìn)階之路】一步步重構(gòu)MVC實(shí)現(xiàn)Struts框架——徹底去掉判斷邏輯（五），我們解決第二個(gè)問(wèn)題：IF...ElSE的問(wèn)題。

? ? ? ?源碼下載

轉(zhuǎn)載于:https://www.cnblogs.com/ainima/p/6330997.html

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