我面临着一个类似的问题 https://stackoverflow.com/questions/1439743/whats-wrong-with-my-listener-in-my-web-xml并了解到我的侦听器类将在读取 web.xml 时实例化。我在侦听器类中有几个函数供主 servlet 的 doPost 使用(它与数据库(mysql)交互以读取/写入有关用户的数据。)以及 HttpSessionListener 的方法。那么是什么阻止了容器加载侦听器类。我收到 404 错误。
snippet:
public class EntryServlet extends HttpServlet{
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
PlayersList playa = new PlayersList(); //listener class
if(!playa.isExisting(params[3])){
if(params[1].equals("Register")){
playa.addPlayer(params);
}
}
else
out.println("Username already exists");
if(playa.isExisting(params[argUName],params[argUPwd])){
HttpSession session = request.getSession(true);
session.setMaxInactiveInterval(600);
HashMap playersMap = playa.getActivePlayers();
//code . .
}
else
out.println("Couldn't locate player Name!");
out.println(playa.getIn());
}
监听类:
public class PlayersList implements HttpSessionListener{
private Connection cn;
private Statement st;
PlayersList(){
try{
Class.forName("com.mysql.jdbc.Driver");
cn = DriverManager.getConnection("jdbc:mysql://localhost/homeDbse\'","root","");
st = cn.createStatement();
}
catch(ClassNotFoundException ce){}
catch(SQLException se){}
catch(Exception e){}
}
public boolean isExisting(String player){
//interaction with dbse
}
public void addPlayer(String[] args){
//interaction with dbse
}
public void sessionCreated(HttpSessionEvent se){
//session managing
}
public void sessionDestroyed(HttpSessionEvent se){
//session managing
}
这种做法是完全错误的。你应该从另一边做。创建一个Player
实现的对象HttpSessionBindingListener http://download.oracle.com/javaee/6/api/javax/servlet/http/HttpSessionBindingListener.html并使用它来代替。
public class Player implements HttpSessionBindingListener {
@Override
public void valueBound(HttpSessionBindingEvent event) {
// Add player to list.
}
@Override
public void valueUnbound(HttpSessionBindingEvent event) {
// Remove player from list.
}
// ...
}
The valueBound()
当你这样做时将会被触发
Player player = new Player(name);
request.getSession().setAttribute("player", player);
The valueUnbound()
当会话过期或删除属性时将被触发。
与具体问题无关,您的代码中存在严重的 JDBC 问题。每当数据库由于打开时间过长而导致连接超时时,该应用程序就会崩溃。您应该在以下位置打开和关闭连接、语句和结果集最短的可能范围。即,将它们关闭在finally
完全相同的块try
执行 SQL 查询的块。
本文内容由网友自发贡献,版权归原作者所有,本站不承担相应法律责任。如您发现有涉嫌抄袭侵权的内容,请联系:hwhale#tublm.com(使用前将#替换为@)