利用servlet监听器，系统启动时创建自定义容器简单例子

web.xml加入：
<listener>
<listener-class>com.telewave.listener.MyInitListener</listener-class>
</listener>

容器类：
package com.telewave.listener;

import java.util.HashMap;
import java.util.Map;

public class MyContainer {

private static MyContainer instance = new MyContainer();
private Map<String, String> map = new HashMap<String, String>();

private MyContainer() {}

public static MyContainer getInstance() {
return instance;
}

public Map<String, String> getMap() {
return map;
}
}


监听类：
package com.telewave.listener;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyInitListener implements ServletContextListener {
//当Servlet容器启动时会执行
public void contextInitialized(ServletContextEvent arg0) {
MyContainer.getInstance();
}
//当Servlet容器停止时会执行
public void contextDestroyed(ServletContextEvent arg0) {

}
}


往容器存入：
MyContainer.getInstance().getMap().put("key", "value");

从容器取出：
MyContainer.getInstance().getMap().get("key");