如何在Struts 2中使用DispatcherListener [英] How to use DispatcherListener in Struts 2

问题描述

Struts2中有一个接口 DispatcherListener 。文档说

There is a interface DispatcherListener in Struts2. The docs says

标记那些想要在 init 和
销毁 Dispatcher 的。

"A interface to tag those that want to execute code on the init and destroy of a Dispatcher."

但是如何使用这个界面。如果我创建一个实现此接口的类，我应该如何配置它为Struts2？

But how to use this interface. If I create a class that implements this interface, how should I configure it to Struts2?

推荐答案

当 Dispatcher 被实例化，它可以在初始化或销毁时发送给监听器通知。参考和代码示例来自此处。

When a Dispatcher is instantiated, it could send to the listener notification when it's initialized or destroyed. The reference and code samples are from here.

简单的用法是通过容器通过 bean 标签实例化bean并将其自身添加到 init 方法并在销毁时删除自己，就像 ClasspathConfigurationProvider 。

The simple usage is to instantiate a bean by the container via bean tag and add themselves in the init method and remove themselves when destroyed like it did by the ClasspathConfigurationProvider.

代码原始只是为了向您展示这个想法

The code is raw just for to show you the idea

struts.xml ：

struts.xml:

<bean type="com.opensymphony.xwork2.config.PackageProvider" name="myBean" class="jspbean.struts.MyBean" />

MyBean.java ：

MyBean.java:

public class MyBean implements ConfigurationProvider, DispatcherListener {
  public MyBean() {
    System.out.println("!!! MyBean !!!");
  }

  @Override
  public void dispatcherInitialized(Dispatcher du) {
    System.out.println("!!! dispatcherInitialized !!!");
  }

  @Override
  public void dispatcherDestroyed(Dispatcher du) {
    System.out.println("!!! dispatcherDestroyed !!!");
  }

  @Override
  public void destroy() {
    System.out.println("!!! destroy !!!");
    Dispatcher.removeDispatcherListener(this);
  }

  @Override
  public void init(Configuration configuration) throws ConfigurationException {
    System.out.println("!!! init !!!");
    Dispatcher.addDispatcherListener(this);
  }

  @Override
  public boolean needsReload() {
    return false;
  }

  @Override
  public void loadPackages() throws ConfigurationException {

  }

  @Override
  public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException {

  }
}

输出：

15:27:50  INFO (org.apache.struts2.spring.StrutsSpringObjectFactory:42) - ... initialized Struts-Spring integration successfully
!!! MyBean !!!
!!! init !!!
jul 18, 2013 3:27:51 PM org.apache.catalina.startup.HostConfig deployDirectory
!!! dispatcherInitialized !!!
[2013-07-18 06:28:11,102] Artifact jspbean:war exploded: Artifact is deployed successfully
INFO: A valid shutdown command was received via the shutdown port. Stopping the Server instance.
INFO: Stopping service Catalina
!!! dispatcherDestroyed !!!

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