實現一個監聽器的接口：（有N種）

1.編寫一個監聽器

實現監聽器的接口

//統計網上在線人數：統計Session

public class olinejqt implements HttpSessionListener {

//創建session監聽：看你的一舉一動

//一旦創建Session就會觸發這個事件

public void sessionCreated(HttpSessionEvent se) {

ServletContext ctx = se.getSession ().getServletContext ();

System.out.println (se.getSession ().getId ());

Integer inter = (Integer) ctx.getAttribute ("session");

//判斷inter為空就是沒有人

if (inter==null){

//加人

inter = new Integer (1); //1人

}else{

int count = inter.intValue ();

inter = new Integer (count+1);//+1=2人

}

ctx.setAttribute ("session",inter);

}

//銷毀Session監聽

//一旦銷毀Session就會觸發這一事件

public void sessionDestroyed(HttpSessionEvent se) {

ServletContext ctx = se.getSession ().getServletContext ();

Integer inter = (Integer) ctx.getAttribute ("session");

//判斷inter為空就是沒有人

if (inter==null){

//加人

inter = new Integer (0); //0人沒人了

}else{

int count = inter.intValue ();

inter = new Integer (count-1);//-1

}

ctx.setAttribute ("session",inter);

}

/**

*Session銷毀

* 1.手動銷毀 getSession() invalidate()

* 2.自動銷毀

*/

}

2.在web中配置監聽器

<!--注冊監聽器 -->

<listener>

<listener-class>com.bubbles.filter.jtqlistener.olinejqt</listener-class>

</listener>

3.看情況是否使用

監聽器和監聽器GUl中理解

過濾器、監聽器常見應用

監聽器：GUl編程中經常使用

package com.bubbles.filter.Server;import java.awt.*; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import java.awt.event.WindowListener;public class TestPane1 {public static void main(String[] args) {Frame frame = new Frame ("中秋節快樂"); //新建一個窗體Panel panel = new Panel (null);//面板frame.setLayout (null); //設置窗體的布局frame.setBounds (300,300,500,500);frame.setBackground (new Color (0,0,255));//設置背景顏色panel.setBounds (50,50,300,300);panel.setBackground (new Color (0,255,0));//設置背景顏色frame.add (panel);frame.setVisible (true);//監聽事件:監聽關閉事件frame.addWindowListener (new WindowListener () {public void windowOpened(WindowEvent e) {System.out.println ("打開");}public void windowClosing(WindowEvent e) {System.out.println ("關閉ing");System.exit (0);}public void windowClosed(WindowEvent e) {System.out.println ("關閉ed");}public void windowIconified(WindowEvent e) {}public void windowDeiconified(WindowEvent e) {}public void windowActivated(WindowEvent e) {System.out.println ("激活");}public void windowDeactivated(WindowEvent e) {System.out.println ("未激活");}});} } 用戶登錄之后才能進入首頁 ！用戶注銷就不能打開主頁！1.用戶登錄之后，向Session中放入用戶的數據2.進入主頁的時候要判斷用戶是否已經登錄；要求：在過濾中實現！ HttpServletRequest request1 = (HttpServletRequest) servletRequest; HttpServletResponse response1 = (HttpServletResponse) servletResponse;if (request1.getSession ().getAttribute (Constant.USER_SESSIN)==null) {response1.sendRedirect ("error.jsp"); }filterChain.doFilter (servletRequest,servletResponse); //過濾器往下走

總結

以上是生活随笔為你收集整理的监听器和监听器过滤器常见应用GUl中理解的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。