层层递进Struts1（一）之由Servlet引入Struts

层层递进Struts1（一）之由Servlet引入Struts2013-12-07 李达在说Struts1之前，我们先来使用Servlet编写一个程序从而了解Struts产生原因和用途：一个简单的增删改查，我们来看一下使用Servlet是如何实现的，为了形象说明，我们从最基本的开始写，然后逐步递进。

第一版

这一版我们使用最常规的做法，增删改查每个功能都使用自己的Servlet，内容如下：

文件树

index.jsp

<form action="servlet/AddUserServlet" method="post">姓名：<input type="text" name="username" /><br/><input type="submit" value="submit"/> </form>

Servlet

为了方便说明此处的四个Servlet内容基本相同，此处以 AddUserServlet和DelServlet为例：

AddUserServlet

package com.tgb.struts1.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class AddUserServlet extends HttpServlet {@Overrideprotected void doGet（HttpServletRequest request, HttpServletResponse response）throws ServletException, IOException {String username=request.getParameter（"username"）;UserManager userManager=new UserManager（）;userManager.add（username）;request.getRequestDispatcher（"/add_success.jsp"）.forward（request, response）;}@Overrideprotected void doPost（HttpServletRequest request, HttpServletResponse response）throws ServletException, IOException {doGet（request, response）;}}

DelUserServlet

package com.tgb.struts1.servlet;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class DelUserServlet extends HttpServlet {@Overrideprotected void doGet（HttpServletRequest request, HttpServletResponse response）throws ServletException, IOException {String username=request.getParameter（"username"）;UserManager userManager=new UserManager（）;userManager.del（username）;request.getRequestDispatcher（"/del_success.jsp"）.forward（request, response）;}@Overrideprotected void doPost（HttpServletRequest request, HttpServletResponse response）throws ServletException, IOException {doGet（request, response）;}}

UserManager

模仿逻辑处理层和数据处理层

package com.tgb.struts1.servlet;import java.util.ArrayList;import java.util.List;public class UserManager {public void add（String username）{System.out.println（"userManager------->add,username="+username）;}public void del（String username）{System.out.println（"userManager------->del,username="+username）;}public void modify（String username）{System.out.println（"userManager------->modify,username="+username）;}public List query（String username）{System.out.println（"userManager------->query,username="+username）;List userList=new ArrayList（）;userList .add（"a"）;userList.add（"b"）;return userList;}}