java中getParameter()中的參數（個人筆記）_

java中getParameter()中的參數（個人筆記）__java

最後更新：2018-07-27 來源：互聯網

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getParameter()函數括弧中的參數是從頁面中傳過來的，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+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title>   <meta http-equiv="pragma" content="no-cache">   <meta http-equiv="cache-control" content="no-cache">   <meta http-equiv="expires" content="0">       <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">   <meta http-equiv="description" content="This is my page">   <!--   <link rel="stylesheet" type="text/css" href="styles.css">   -->  </head>    <body>    <form action="update.do" method="post">       <input type="hidden" name="userId" value="${user.id}" />        <table>          <tr>             <td>使用者名稱：</td>             <td><input type="text" name="name" value="${user.name}"/></td>          </tr>          <tr>             <td>密碼：</td>             <td><input type="text" name="password" value="${user.password}"/></td>          </tr>          <tr>             <td colspan="2">                <input type="submit" value="提交"/>             </td>          </tr>       </table>    </form>  </body></html>

下面是控制層：

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();就是得到了頁面中userid的值 備忘：trim()方法是為了去掉前後空格

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