如何在 Struts 2 中使用 DispatcherListener

有一个界面DispatcherListener在Struts2中。文档说

“一个接口来标记那些想要在init and destroy of a Dispatcher."

但是这个接口怎么用呢。如果我创建一个实现这个接口的类，我应该如何将它配置到Struts2？

When a Dispatcher被实例化后，它可以在初始化或销毁时向侦听器发送通知。参考和代码示例来自here.

简单的用法是通过容器实例化一个beanbean标记并将自己添加到init方法并在被破坏时自行移除，就像被ClasspathConfigurationProvider.

该代码是原始的，只是为了向您展示这个想法

struts.xml:

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

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 !!!