这段jsp的代码谁能给解释一下呀?

import java.io.IOException;
import java.sql.Date;
import java.text.ParseException;
import java.text.SimpleDateFormat;

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

import com.wang.mode.News;
import com.wang.mode.NewsImpl;
import com.wang.mode.NewsInterface;
import com.wang.mode.User;

public class NewsServlet extends HttpServlet {

protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(req, resp);
}

protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
User user=(User)req.getSession().getAttribute("user");//就是这一段和下面的几行不明白
String title=req.getParameter("title");
String content=req.getParameter("content");
String pubDate=req.getParameter("pubdate");
News news=new News();
news.setTitle(title);
news.setContent(content);
news.setUser(user);
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
try {
news.setPubDate(sdf.parse(pubDate));
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
NewsInterface newsInterface=new NewsImpl();
boolean b=newsInterface.addNews(news);
if(b){
resp.sendRedirect("list.jsp");
}else{
resp.sendRedirect("inser_error.jsp");
}
}
}

User user=(User)req.getSession().getAttribute("user");//获取保存的用户session值

String title=req.getParameter("title");//获取页面提交的title值
String content=req.getParameter("content");//获取页面提交的content值
String pubDate=req.getParameter("pubdate");//获取页面提交的时间
News news=new News();//实例化News实体s
news.setTitle(title);//为title赋值
news.setContent(content);//为content赋值
news.setUser(user);//为user赋值
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");//格式化日期格式
try {//日期异常处理
news.setPubDate(sdf.parse(pubDate));
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
NewsInterface newsInterface=new NewsImpl();//实例化NewsInterface

boolean b=newsInterface.addNews(news);//添加
if(b){//判断是否成功
resp.sendRedirect("list.jsp");//成功后跳转list.jsp页面
}else{
resp.sendRedirect("inser_error.jsp");//失败跳转inser_error.jsp页面
}
不知道还有哪句不明白的。

//从request中获得参数名为title的对象的值 String title=req.getParameter("title"); //从request中获得参数名为content的对象的值 String content=req.getParameter("content"); //从request中获得参数名为pubdate的对象的值 String pubDate=req.getParameter("pubdate");

//创建一个News对象 News news=new News(); //给Title,Content,User三个属性赋值 news.setTitle(title); news.setContent(content); news.setUser(user);

//创建一个SimpleDateFormat对象 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd"); try { //格式化从request对象中获得的pubdate为yyyy-mm-dd格式并赋值给news对象的PubDate属性 news.setPubDate(sdf.parse(pubDate)); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } //创建一个NewsImpl对象 NewsInterface newsInterface=new NewsImpl();

//调用NewsImpl的addNews()方法,该方法返回值为boolean boolean b=newsInterface.addNews(news); if(b){ //添加成功,进入news列表页面 resp.sendRedirect("list.jsp"); }else{ //失败,进入错误页面 resp.sendRedirect("inser_error.jsp"); }