[JAVA]如何讓tomcat啓動時執行某一方法

import java.util.Timer; 

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

public class TestListener implements ServletContextListener { 
  private Timer timer = null; 

  public void contextInitialized(ServletContextEvent event) { 
    timer = new Timer(true); 
    timer.schedule(new TestTimer(), 0, 86400000);//milliseconds 
  } 

  public void contextDestroyed(ServletContextEvent event) { 
    timer.cancel(); 
  } 
} 

------------------------------------------ 

import java.util.TimerTask; 

public class TestTimer extends TimerTask { 
  public void run() { 
    // do something ... 
  } 
} 

------------------------------------------ 

web.xml: 

<listener> 
<listener-class>test.TestListener</listener-class> 
</listener> 

創建監聽.tomcat服務器啓動時自動執行監聽器的方法