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getter：

public 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：

也可以看看：