JSP显示新闻
Posted 轻羽飞扬
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一、用户登录：
采用之前的邮件登录系统的界面和验证
1 //设置数据格式 2 response.setContentType("text/html;charset=utf-8"); 3 request.setCharacterEncoding("utf-8"); 4 PrintWriter pw = response.getWriter(); 5 6 //获取值 7 String userID = request.getParameter("userID"); 8 String userPWD = request.getParameter("userPWD"); 9 10 //连接数据库 11 Connection conn; 12 13 //数据库连接驱动(mysql8的连接需要加上cj) 14 String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver"; 15 16 //需要使用的数据库路径 17 String url = "jdbc:mysql://localhost:3306/javaee?useSSL=false&serverTimezone=GMT%2B8"; 18 19 //数据库使用者信息 20 String user = "root"; 21 String password = "1234567890"; 22 23 try { 24 Class.forName(JDBC_DRIVER); 25 conn = DriverManager.getConnection(url, user ,password); 26 if (!conn.isClosed()){ 27 System.out.println("数据库连接成功"); 28 } 29 Statement stmt = conn.createStatement(); 30 String sql_select = "select * from userinfo where id=\'"+ userID +"\' and password=\'"+ userPWD +"\'"; 31 ResultSet result = stmt.executeQuery(sql_select); 32 if (result.next()) { 33 //登录成功的提示 34 System.out.println(userID + " " + userPWD); 35 System.out.println("用户名：" + userID + " 密码:" + userPWD); 36 System.out.println("登录成功，欢迎你 " + userID); 37 pw.println("登录成功" + "<br>" + "您的用户名：" + userID + "<br>" + "您的密码：" + userPWD); 38 39 //登录成功时设置Cookie 40 Cookie userCookie = new Cookie("userID", userID); 41 42 //设置cookie保存的最大时间 43 userCookie.setMaxAge(60*60*24*30); 44 response.addCookie(userCookie); 45 46 //用户密码也用Cookie记录，方便自动登录 47 Cookie pwdCookie = new Cookie("userPWD", userPWD); 48 userCookie.setMaxAge(60*60*24*30); 49 response.addCookie(pwdCookie); 50 51 //设置session 52 HttpSession session = request.getSession(); 53 session.setMaxInactiveInterval(10); 54 ServletContext sc = getServletContext(); 55 Object number = sc.getAttribute("onlineNumber"); 56 57 pw.println("当前网页在线人数:" + number); 58 59 }else{ 60 System.out.println("用户名或者密码错误"); 61 pw.println("登录失败"+"<br>"+"用户名或者密码错误"); 62 } 63 64 //关闭数据库的连接 65 result.close(); 66 conn.close(); 67 68 }catch (ClassNotFoundException e){ 69 System.out.println("数据库驱动没有安装"); 70 e.printStackTrace(); 71 }catch (SQLException e){ 72 System.out.println("数据库连接失败"); 73 e.printStackTrace(); 74 }
二、新闻显示：
1、创建数据表：
1 CREATE DATABASE /*!32312 IF NOT EXISTS*/`NewsDB` /*!40100 DEFAULT CHARACTER SET utf8 */; 2 3 USE `NewsDB`; 4 5 /*Table structure for table `news` */ 6 7 DROP TABLE IF EXISTS `news`; 8 9 CREATE TABLE `news` ( 10 `id` INT(11) NOT NULL AUTO_INCREMENT, 11 `title` VARCHAR(100) DEFAULT NULL, 12 `conetnt` VARCHAR(1000) DEFAULT NULL, 13 `author` VARCHAR(50) DEFAULT NULL, 14 `addtime` DATETIME DEFAULT NULL, 15 PRIMARY KEY (`id`) 16 ) ENGINE=INNODB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8; 17 18 /*Data for the table `news` */ 19 20 INSERT INTO `news`(`id`,`title`,`conetnt`,`author`,`addtime`) VALUES (1,\'端午节的来源\',\'端午节，又称端阳节、龙舟节、重午节、龙节、正阳节、天中节等，节期在农历五月初五，是中国民间的传统节日。端午节源自天象崇拜，由上古时代祭龙演变而来。仲夏端午，苍龙七宿飞升至正南中天，是龙飞天的日子，即如《易经·乾卦》第五爻的爻辞曰：“飞龙在天”。端午日龙星既“得中”又“得正”，乃大吉大利之象。端午节的起源涵盖了古老星象文化、人文哲学等方面内容，蕴含着深邃丰厚的文化内涵；在传承发展中杂揉了多种民俗为一体，节俗内容丰富。扒龙舟与食粽是端午节的两大礼俗，这两大礼俗在中国自古传承，至今不辍。\',\'test\',\'2020-06-25 10:19:42\'); 21 22 /*Table structure for table `user` */ 23 24 DROP TABLE IF EXISTS `user`; 25 26 CREATE TABLE `user` ( 27 `uid` INT(11) NOT NULL AUTO_INCREMENT, 28 `userName` VARCHAR(30) DEFAULT NULL, 29 `pw` VARCHAR(15) DEFAULT NULL, 30 PRIMARY KEY (`uid`) 31 ) ENGINE=INNODB AUTO_INCREMENT=6 DEFAULT CHARSET=gb2312; 32 33 /*Data for the table `user` */ 34 35 INSERT INTO `user`(`uid`,`userName`,`pw`) VALUES (1,\'admin\',\'admin\');
2、新增Servlet : NewsController.java 并配置在WEB.XML中
<servlet>
<servlet-name>NewsController</servlet-name>
<servlet-class>servlet.NewsController</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>NewsController</servlet-name>
<url-pattern>/NewsController</url-pattern>
</servlet-mapping>
在NewsController.java 中doGet中重写doPost方法并在doPost方法中获取action参数，根据参数不同分别进行不同请求
3、创建service类 NewsService.java，在类中调用DAO中并返回新闻信息
public class NewsService { public List<NewsBean> query_all_news() { NewsDao newsDao = new NewsDao(); return newsDao.query_all_news(); } public NewsBean getNews(String id) { NewsDao newsDao = new NewsDao(); return newsDao.getNews(id); } }
4、新增DBUtils.java 及 NewsDao.java类
在DBUtils.java中添加连接数据库及关闭数据库代码
public static Connection getConnection(){ String dbUserName = "root"; String dbUserPasswd = "123456"; String dbURL = "jdbc:mysql://localhost:3406/NewsDB?serverTimezone=Asia/Shanghai"; Connection conn = null; try { Class.forName("com.mysql.jdbc.Driver"); conn = (Connection) DriverManager.getConnection(dbURL,dbUserName,dbUserPasswd); } catch (ClassNotFoundException | SQLException e) { e.printStackTrace(); } return conn; } public static void closeConnection(Connection conn) { if(conn != null){ try { conn.close(); } catch (SQLException e) { // TODO: handle exception e.printStackTrace(); } } }
public List<NewsBean> query_all_news() { Connection conn = DBUtils.getConnection(); String sql = "select * from news"; ArrayList<NewsBean> results = new ArrayList<NewsBean>(); try { PreparedStatement ps = (PreparedStatement) conn.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while(rs.next()){ NewsBean temp = new NewsBean(); temp.setId(rs.getString("id")); temp.setTitle(rs.getString("title")); temp.setConetnt(rs.getString("conetnt")); temp.setAuthor(rs.getString("author")); temp.setAddtime(rs.getDate("addtime")); results.add(temp); } rs.close(); ps.close(); } catch (SQLException e) { e.printStackTrace(); }finally { DBUtils.closeConnection(conn); } return results; } public NewsBean getNews(String id) { Connection conn = DBUtils.getConnection(); String sql = "select * from news where id=\'"+id+"\' "; NewsBean result = new NewsBean(); try { PreparedStatement ps = (PreparedStatement) conn.prepareStatement(sql); ResultSet rs = ps.executeQuery(); while(rs.next()){ result.setId(rs.getString("id")); result.setTitle(rs.getString("title")); result.setConetnt(rs.getString("conetnt")); result.setAuthor(rs.getString("author")); result.setAddtime(rs.getDate("addtime")); } rs.close(); ps.close(); } catch (SQLException e) { e.printStackTrace(); }finally { DBUtils.closeConnection(conn); } return result; }
5、前端显示页面：
<c:forEach items="${newsList }" var="ctxt">
<tr>
<td>
${ctxt.title } </td>
<td> ${ctxt.author } </td>
<td> ${ctxt.addtime } </td>
<td><a href="/JspNewsList/NewsController?action=toShowNews&id=${ctxt.id }">查看详情</a></td>
</tr>
</c:forEach>
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