一、概述

这介绍中表达的比较有价值的信息是各个service是相互隔离的，但是又共享jvm的一些基础类。

/**
 * A <strong>Service</strong> is a group of one or more
 * <strong>Connectors</strong> that share a single <strong>Container</strong>
 * to process their incoming requests.  This arrangement allows, for example,
 * a non-SSL and SSL connector to share the same population of web apps.
 * <p>
 * A given JVM can contain any number of Service instances; however, they are
 * completely independent of each other and share only the basic JVM facilities
 * and classes on the system class path.
 *
 * @author Craig R. McClanahan
 */

二、阅读源码

Service中的组件其实和Server中的组件大差不差，我这里重点介绍Service广播事件的一个方法。

 其中的顺序大概是这样的：StandardService调用PropertyChangeSupport的广播方法，然后利用PropertyChangeEvent传参完成事件广播。其中比较重要的就是PropertyChangeSupport类，我接下会介绍它的广播方法。

1、PropertyChangeSupport

//用来装监听器的map
private PropertyChangeListenerMap map = new PropertyChangeListenerMap();


    public void firePropertyChange(PropertyChangeEvent event) {
        Object oldValue = event.getOldValue();
        Object newValue = event.getNewValue();

        //进行条件判断，判断通过则进入下一步
        if (oldValue == null || newValue == null || !oldValue.equals(newValue)) {
            String name = event.getPropertyName();

            //拿到通用监听器
            PropertyChangeListener[] common = this.map.get(null);
            //拿到指定监听器
            PropertyChangeListener[] named = (name != null)
                        ? this.map.get(name)
                        : null;


            //分别进行广播
            fire(common, event);
            fire(named, event);
        }
    }



//这是最后执行广播的方法就是调用了监听器，把事件变化发送出去
  private static void fire(PropertyChangeListener[] listeners, PropertyChangeEvent event) {
        if (listeners != null) {
            for (PropertyChangeListener listener : listeners) {
                listener.propertyChange(event);
            }
        }
    }