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;
/**
* 使用servlet做相关的控制，转向多个（V）视图
* @author liang
*
*/
public class TestServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//取得访问的URI
String reqeuestURI = request.getRequestURI();
System.out.println(reqeuestURI);
//截取URI，获得路径
String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));
System.out.println(path);
//获得表单数据
String username = request.getParameter("username");
UserManager userManager = new UserManager();
String forward ="";
//根据url执行相关的功能
//等于添加，调用添加方法，添加成功转到添加页面
if("/servlet/addUser".equals(path)){
//调用添加的业务逻辑
userManager.add(username);
forward ="/add_success.jsp";
//删除，调用删除方法，删除成功转到删除
}else if("/servlet/delUser".equals(path)){
//调用删除的业务逻辑
userManager.del(username);
forward ="/servlet/delUser";
//修改，调用修改方法，修改成功转到修改页面
}else if("/servlet/modifyUser".equals(path)){
//调用修改的业务逻辑
userManager.modify(username);
forward ="/modify_success.jsp";
//查询，调用查询方法，查询成功转到查询成功页面
}else if("/servlet/queryUser".equals(path)){
//调用查询的业务逻辑
List userList = userManager.query(username);
request.setAttribute("userList", userList);
forward ="/query_success.jsp";
}else{
throw new RuntimeException("请求失败");
}
//统一完成转向
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 {
//获取参数
String username = req.getParameter("username");
UserManager userManager = new UserManager();
//调用业务逻辑
userManager.add(username);
//返回跳转页面
return "/add_success.jsp";
}
}
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>//获取参数
String username = req.getParameter("username");
UserManager userManager = new UserManager();
//调用业务逻辑
userManager.del(username);
//返回跳转页面
return "/del_success.jsp";
}
}
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 {
//获取参数
String username = req.getParameter("username");
//调用业务逻辑
UserManager userManager = new UserManager();
userManager.modify(username);
//返回跳转页面
return "/modify_success.jsp";
}
}
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 {
//获取参数
String username = req.getParameter("username");
//调用业务逻辑
UserManager userManager = new UserManager();
List userList = userManager.query(username);
req.setAttribute("userList", userList);
userManager.query(username);
//返回跳转页面
return "/query_success.jsp";
}
}
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做相关的控制，转向多个（V）视图
* @author liang
*
*/
public class TestServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//取得访问的URI
String reqeuestURI = request.getRequestURI();
System.out.println(reqeuestURI);
//截取URI，获得路径
String path = reqeuestURI.substring(reqeuestURI.indexOf("/",1), reqeuestURI.indexOf("."));
System.out.println(path);
Action action = null;
//等于添加，调用AddUserAction
if ("/servlet/addUser".equals(path)) {
action = new AddUserAction();
//等于删除，调用DelUserAction
}else if ("/servlet/delUser".equals(path)) {
action = new DelUserAction();
//等于修改，调用ModifyUserAction
}else if ("/servlet/modifyUser".equals(path)) {
action = new ModifyUserAction();
//等于查询，调用QueryUserAction
}else if ("/servlet/queryUser".equals(path)) {
action = new QueryUserAction();
}else {
throw new RuntimeException("请求失败");
}
String forward = null;
//返回不同的转向页面
try {
forward = action.execute(request, response);
} catch (Exception e) {
e.printStackTrace();
}
//根据路径,统一完成转向
request.getRequestDispatcher(forward).forward(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
}
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。
【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）
原文地址：http://blog.csdn.net/jiuqiyuliang/article/details/39054165
