解答例 - 実習課題３ - ８．リスナー２

（実習課題３）

任意のWebアプリケーションにHttpSessionActivationListenerを実装したオブジェクトを追加し、HttpSessionActivationListenerが動作するタイミングを確認すること。

解答例

/*
 * CountBean.java TECHSCORE Java Servlet8章 実習課題3
 *
 * Copyright (c) 2004 Four-Dimensional Data, Inc.
 */
package com.techscore.servlet.chapter8.exercise3;

import java.io.Serializable;

import javax.servlet.http.HttpSessionActivationListener;
import javax.servlet.http.HttpSessionEvent;

public class CountBean implements HttpSessionActivationListener, Serializable {

    private int count = 0;

    public String toString(String functionName) {
        return new String("Servlet8-3 " + functionName + "\tcount=" + count);
    }

    synchronized public void increase() {
        count++;
    }

    synchronized public void decrease() {
        count--;
    }

    public int getCount() {
        return count;
    }

    public void sessionDidActivate(HttpSessionEvent event) {
        event.getSession().getServletContext().log(
                toString("sessionDidActivate()"));
    }

    public void sessionWillPassivate(HttpSessionEvent event) {
        event.getSession().getServletContext().log(
                toString("sessionWillPassivate()"));
    }
}

/*
 * UserCountListener.java TECHSCORE Java Servlet8章 実習課題3
 *
 * Copyright (c) 2004 Four-Dimensional Data, Inc.
 */
package com.techscore.servlet.chapter8.exercise3;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class UserCountListener implements HttpSessionListener {

    private CountBean count = new CountBean();

    public void sessionCreated(HttpSessionEvent event) {
        count.increase();
        event.getSession().setAttribute("userCount3", count);
    }

    public void sessionDestroyed(HttpSessionEvent event) {
        count.decrease();
    }

}

/*
 * UserCountListener.java TECHSCORE Java Servlet8章 実習課題3
 *
 * Copyright (c) 2004 Four-Dimensional Data, Inc.
 */
package com.techscore.servlet.chapter8.exercise3;

import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class UserCountListener implements HttpSessionListener {

    private CountBean count = new CountBean();

    public void sessionCreated(HttpSessionEvent event) {
        count.increase();
        event.getSession().setAttribute("userCount3", count);
    }

    public void sessionDestroyed(HttpSessionEvent event) {
        count.decrease();
    }

}