1.复习java的事件机制

java事件机制包括三个部分：事件、事件监听器、事件源。

事件：一般继承自java.util.EventObject类，封装了事件源对象及跟事件相关的信息。

事件监听器：实现java.util.EventListener接口,注册在事件源上,当事件源的属性或状态改变时,取得相应的监听器调用其内部的回调方法。

事件源：事件发生的地方，由于事件源的某项属性或状态发生了改变(比如BUTTON被单击、TEXTBOX的值发生改变等等)导致某项事件发生。

2. tomcat的lifecycle

事件定义

public final class LifecycleEvent extends EventObject {

    private static final long serialVersionUID = 1L;

    // ----------------------------------------------------------- Constructors

    /**

     * Construct a new LifecycleEvent with the specified parameters.

     *

     * @param lifecycle Component on which this event occurred

     * @param type Event type (required)

     * @param data Event data (if any)

     */

    public LifecycleEvent(Lifecycle lifecycle, String type, Object data) {

        super(lifecycle);

        this.type = type;

        this.data = data;

    }
}

事件监听器

/**

 * Interface defining a listener for significant events (including "component

 * start" and "component stop" generated by a component that implements the

 * Lifecycle interface. The listener will be fired after the associated state

 * change has taken place.

 *

 * @author Craig R. McClanahan

 * @version $Id: LifecycleListener.java 1200160 2011-11-10 05:35:13Z kkolinko $

 */

public interface LifecycleListener {

    /**

     * Acknowledge the occurrence of the specified event.

     *

     * @param event LifecycleEvent that has occurred

     */

    public void lifecycleEvent(LifecycleEvent event);

}

 *            start()

 *  -----------------------------

 *  |                           |

 *  | init()                    |

 * NEW ->-- INITIALIZING        |

 * | |           |              |     ------------------<-----------------------

 * | |           |auto          |     |                                        |

 * | |          \|/    start() \|/   \|/     auto          auto         stop() |

 * | |      INITIALIZED -->-- STARTING_PREP -->- STARTING -->- STARTED -->---  |

 * | |         |                                                  |         |  |

 * | |         |                                                  |         |  |

 * | |         |                                                  |         |  |

 * | |destroy()|                                                  |         |  |

 * | -->-----<--       auto                    auto               |         |  |

 * |     |       ---------<----- MUST_STOP ---------------------<--         |  |

 * |     |       |                                                          |  |

 * |    \|/      ---------------------------<--------------------------------  ^

 * |     |       |                                                             |

 * |     |      \|/            auto                 auto              start()  |

 * |     |  STOPPING_PREP ------>----- STOPPING ------>----- STOPPED ---->------

 * |     |                                ^                  |  |  ^

 * |     |               stop()           |                  |  |  |

 * |     |       --------------------------                  |  |  |

 * |     |       |                                  auto     |  |  |

 * |     |       |                  MUST_DESTROY------<-------  |  |

 * |     |       |                    |                         |  |

 * |     |       |                    |auto                     |  |

 * |     |       |    destroy()      \|/              destroy() |  |

 * |     |    FAILED ---->------ DESTROYING ---<-----------------  |

 * |     |                        ^     |                          |

 * |     |     destroy()          |     |auto                      |

 * |     -------->-----------------    \|/                         |

 * |                                 DESTROYED                     |

 * |                                                               |

 * |                            stop()                             |

 * --->------------------------------>------------------------------

public interface Lifecycle 

3. lifecycle在tomcat中的使用。

public interface Server extends Lifecycle

public interface Service extends Lifecycle 

public interface Container extends Lifecycle