一个公司备案两个网站,如何注册自己的平台,网站建站大约多少钱,九江市住房和城乡建设局官方网站您没有将某些内容传递给servlet.你只需让servlet访问一些东西.您应该摆脱main()方法并将数据库交互代码移动到DAO类中.我还给模型类(带有时区和位置)一个以大写字母开头的更敏感的名称.总而言之,您应该更新代码,使其看起来如下所示#xff1a;模型类,区域(只要它有意义,任意你…您没有将某些内容传递给servlet.你只需让servlet访问一些东西.您应该摆脱main()方法并将数据库交互代码移动到DAO类中.我还给模型类(带有时区和位置)一个以大写字母开头的更敏感的名称.总而言之,您应该更新代码,使其看起来如下所示模型类,区域(只要它有意义,任意你想要的名称),它应该只代表一个实体public class Area {private String location;private String timezone;public String getLocation() { return location; }public String getTimezone() { return timezone; }public void setLocation(String location) { this.location location; }public void setTimezone(String timezone) { this.timezone timezone; }}基本连接管理器类,数据库,这里只加载驱动程序一次,并为连接提供一个getterpublic class Database {private String url;private String username;private String password;public Database(String driver, String url, String username, String password) {try {Class.forName(driver);} catch (ClassNotFoundException e) {throw new RuntimeException(Driver class is missing in classpath, e);}this.url url;this.username username;this.password password;}public Connection getConnection() {return DriverManager.getConnection(url, username, password);}}DAO类,AreaDAO,这里放置所有数据库交互方法public class AreaDAO {private Database database;public AreaDAO(Database database) {this.database database;}public List list() throws SQLException {Connection connection null;PreparedStatement statement null;ResultSet resultSet null;List areas new ArrayList();try {connection database.getConnection();statement connection.prepareStatement(SELECT location, timezone FROM userclient);resultSet statement.executeQuery();while (resultSet.next()) {Area area new Area();area.setLocation(resultSet.getString(location));area.setTimezone(resultSet.getString(timezone));areas.add(area);}} finally {if (resultSet ! null) try { resultSet.close(); } catch (SQLException logOrIgnore) {}if (statement ! null) try { statement.close(); } catch (SQLException logOrIgnore) {}if (connection ! null) try { connection.close(); } catch (SQLException logOrIgnore) {}}return areas;}}最后,在servlet中初始化DAO一次并获取HTTP方法中的列表public class AreaServlet extends HttpServlet {private AreaDAO areaDAO;public void init() throws ServletException {String driver com.mysql.jdbc.Driver;String url jdbc:mysql://localhost:3306/dbname;String username user;String password pass;Database database new Database(driver, url, username, password);this.areaDAO new AreaDAO(database);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {try {List areas areaDAO.list();request.setAttribute(areas, areas);request.getRequestDispatcher(/WEB-INF/areas.jsp).forward(request, response);} catch (SQLException e) {throw new ServletException(Cannot retrieve areas, e);}}}将此servlet映射到web.xml中的/ areas区域的url-pattern上,以便您可以在http://example.com/contextname/areas之前调用它/WEB-INF/areas.jsp看起来像这样,假设您要显示表中的区域${area.location}${area.timezone}也可以看看
