servlet启动服务的两种方式

1、配置监听，实现ServletContextListener

web.xml:

<listener>
      <display-name>startThreadHelloWorld</display-name>
      <listener-class>com.relive.listener.HelloListener</listener-class>

  </listener>

java代码：

public class HelloListener implements ServletContextListener {

	@Override
	public void contextDestroyed(ServletContextEvent sce) {
		System.out.println("执行销毁方法...");
	}

	@Override
	public void contextInitialized(ServletContextEvent sce) {
		System.out.println("启动监听，执行初始化方法...");
	}

}

在contextInitialized(ServletContextEvent sce)方法中启动线程或任意其他服务。

2、配置servlet，继承GenericServlet类

web.xml:

 <servlet>
  	<servlet-name>helloServlet</servlet-name>
  	<servlet-class>com.relive.servlet.HelloServlet</servlet-class>
	<load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
  	<servlet-name>helloServlet</servlet-name>
  	<url-pattern>/helloServlet/*</url-pattern>
  </servlet-mapping>

java代码：

public class HelloServlet extends GenericServlet {

	private static final long serialVersionUID = -566043926299855050L;

	public void init(ServletConfig config) throws ServletException {
		System.out.println("执行servlet..init方法..");
	}
	
	public void service(ServletRequest sRequest, ServletResponse sResponse)
			throws ServletException, IOException {
		System.out.println("执行servlet..service方法..");
	}

}