java中getParameter()中的参数 （个人笔记）

  getParameter()函数括号中的参数是从页面中传过来的，比如 edit.jsp中userid：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

  
    href="<%=basePath%>">
    
    
   http-equiv="pragma" content="no-cache">
   http-equiv="cache-control" content="no-cache">
   http-equiv="expires" content="0">    
   http-equiv="keywords" content="keyword1,keyword2,keyword3">
   http-equiv="description" content="This is my page">
   
  
  
  
    
action="update.do" method="post">
       type="hidden" name="userId" value="${user.id}" /> 
                                                                                                                                           


用户名：
type="text" name="name" value="${user.name}"/>


密码：
type="text" name="password" value="${user.password}"/>


colspan="2">
                type="submit" value="提交"/>
             


    
  

下面是控制层：

package com.demo.controller;

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.demo.dao.UserDao;
import com.demo.entity.User;

public class UpdateController extends HttpServlet {
   
   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      doPost(req, resp);
   }

   protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      String ids = req.getParameter("userId").trim();
      Long id = (long) 0;
      if (ids != null) {
         id = Long.parseLong(ids);
      }
      String name = req.getParameter("name").trim();
      String password = req.getParameter("password").trim();
      User user = new User();
      user.setId(id);
      user.setName(name);
      user.setPassword(password);
      UserDao userDao = new UserDao();
      userDao.updateUser(user);
      resp.sendRedirect("list.do");
   }
}

其中

String ids = req.getParameter("userId").trim();就是得到了页面中userid的值 备注：trim()方法是为了去掉前后空格