1-从Servlet认识Struts实现的基本原理

1、一个表单（index.jsp）

<!-- 在此例题中修改action的值，查看转向的效果 -->
<form action="userModify.do" method="post">
    姓名：<input type="text" name="username"><br>
    <input type="submit" value="提交">
</form>

2、web.xml配置文件，配置表单提交后，用来指明处理该表单的类

<servlet>
      <servlet-name>action</servlet-name>
      <servlet-class>net.nyist.servlet.ServletActionForm</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>action</servlet-name>
      <url-pattern>*.do</url-pattern>
  </servlet-mapping>

3、处理表单的类--ServletActionForm.java

package net.nyist.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 ServletActionForm extends HttpServlet {

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //获取表单中传过来的值
        String username = req.getParameter("username");
        //得到请求的http地址（如：/from_servlet_start/user.do）
        String uri = req.getRequestURI();
        //去掉后面的.do （如：/from_servlet_start/user）
        uri = uri.substring(0, uri.indexOf("."));
        //去掉/from_servlet_start/，赛选出user
        uri = uri.substring(uri.lastIndexOf("/") + 1);
        
        Action action = null;
        String path = "";
        //处理action
        if("userAdd".equals(uri)) {
            action = new UserAddAction();
            path = action.execute(req, resp);
        } else if("userDelete".equals(uri)) {
            action = new UserDeleteAction();
            path = action.execute(req, resp);
        } else if("userModify".equals(uri)) {
            action = new UserModifyAction();
            path = action.execute(req, resp);
        }    
        
        //跳转页面
        req.getRequestDispatcher(path).forward(req, resp);
    }

}

4、Actoin接口

package net.nyist.servlet;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface Action {
    public String execute(HttpServletRequest req, HttpServletResponse resp);
}

5、ServletActoinForm.java中用到的类如下：

      ---UserAddAction.java类

package net.nyist.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class UserAddAction implements Action {

    public String execute(HttpServletRequest req, HttpServletResponse resp) {
        // TODO Auto-generated method stub
        return "/userAdd.jsp";
    }

}

      ----UserDeleteAction.java类

package net.nyist.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class UserDeleteAction implements Action {

    public String execute(HttpServletRequest req, HttpServletResponse resp) {
        // TODO Auto-generated method stub
        return "/userDelete.jsp";
    }

}

      ----UserModifyAction.java类

package net.nyist.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class UserModifyAction implements Action {

    public String execute(HttpServletRequest req, HttpServletResponse resp) {
        // TODO Auto-generated method stub
        return "/userModify.jsp";
    }

}