结构图
Listener:
首先定义一个Listener，实现以下接口：
HttpSessionListener(用来监控session的创建，销毁等)
ServletRequestListener(用于监控servlet上下文request)
ServletRequestAttributeListener(用于监控request中的attribute的操作)
public class TestListener implements HttpSessionListener,ServletRequestListener,ServletRequestAttributeListener {
private Logger logger = LoggerFactory.getLogger(TestListener.class);
//sessionListener start!
public void sessionCreated(HttpSessionEvent arg0) {
logger.info(".......TestListener sessionCreated().......");
}
public void sessionDestroyed(HttpSessionEvent arg0) {
logger.info(".......TestListener sessionDestroyed().......");
}
//sessionListener end!
//requestListener start!
public void requestInitialized(ServletRequestEvent arg0) {
logger.info("......TestListener requestInitialized()......");
}
public void requestDestroyed(ServletRequestEvent arg0) {
logger.info("......TestListener requestDestroyed()......");
}
//requestListener end!
//attributeListener start!
public void attributeAdded(ServletRequestAttributeEvent srae) {
logger.info("......TestListener attributeAdded()......");
}
public void attributeRemoved(ServletRequestAttributeEvent srae) {
logger.info("......TestListener attributeRemoved()......");
}
public void attributeReplaced(ServletRequestAttributeEvent srae) {
logger.info("......TestListener attributeReplaced()......");
}
//attributeListener end!
}
Filter：
public class TestFilter implements Filter {
private Logger logger = LoggerFactory.getLogger(TestFilter.class);
public void destroy() {
logger.info("..............execute TestFilter destory()..............");
}
public void doFilter(ServletRequest arg0, ServletResponse arg1,FilterChain arg2) throws IOException, ServletException {
logger.info("..............execute TestFilter doFilter()..............");
arg2.doFilter(arg0, arg1);
}
public void init(FilterConfig arg0) throws ServletException {
logger.info("..............execute TestFilter init()..............");
}
}
Servlet
public class TestServlet extends HttpServlet {
private Logger logger = LoggerFactory.getLogger(TestServlet.class);
/**
*
*/
private static final long serialVersionUID = -4263672728918819141L;
@Override
public void init() throws ServletException {
logger.info("...TestServlet init() init..........");
super.init();
}
@Override
public void destroy() {
logger.info("...TestServlet init() destory..........");
super.destroy();
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
logger.info("...TestServlet doPost() start..........");
//操作attribute
request.setAttribute("a", "a");
request.setAttribute("a", "b");
request.getAttribute("a");
request.removeAttribute("a");
//操作session
request.getSession().setAttribute("a", "a");
request.getSession().getAttribute("a");
request.getSession().invalidate();
logger.info("...TestServlet doPost() end..........");
}
}
配置XML
<!-- 测试filter -->
<filter>
<filter-name>TestFilter</filter-name>
<filter-class>com.xy.web.filter.TestFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>TestFilter</filter-name>
<url-pattern>*.do</url-pattern>
</filter-mapping>
<!-- 测试servlet -->
<servlet>
<servlet-name>TestServlet</servlet-name>
<servlet-class>com.xy.web.servlet.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TestServlet</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
<!-- 测试listener -->
<listener>
<listener-class>com.xy.web.listener.TestListener</listener-class>
</listener>
配置好以后启动项目。
加载顺序
从启动日志来看，
启动的顺序为listener->Filter->servlet.
简单记为：理(Listener)发(Filter)师(servlet).
执行的顺序不会因为三个标签在配置文件中的先后顺序而改变。
生命周期
第一次访问：
2016-01-14 00:03:03,991 INFO TestListener:26 - ......TestListener requestInitialized()......
2016-01-14 00:03:04,001 INFO TestServlet:24 - ...TestServlet init() init..........
2016-01-14 00:03:04,011 INFO TestFilter:23 - ..............execute TestFilter doFilter()..............
2016-01-14 00:03:15,275 INFO TestServlet:42 - ...TestServlet doPost() start..........
2016-01-14 00:03:16,255 INFO TestListener:36 - ......TestListener attributeAdded()......
2016-01-14 00:03:16,853 INFO TestListener:44 - ......TestListener attributeReplaced()......
2016-01-14 00:03:18,561 INFO TestListener:40 - ......TestListener attributeRemoved()......
2016-01-14 00:03:20,065 INFO TestListener:16 - .......TestListener sessionCreated().......
2016-01-14 00:03:22,908 INFO TestListener:20 - .......TestListener sessionDestroyed().......
2016-01-14 00:03:25,624 INFO TestServlet:52 - ...TestServlet doPost() end..........
2016-01-14 00:03:27,746 INFO TestListener:30 - ......TestListener requestDestroyed()......
第二次访问：
2016-01-14 00:04:08,908 INFO TestListener:26 - ......TestListener requestInitialized()......
2016-01-14 00:04:08,909 INFO TestFilter:23 - ..............execute TestFilter doFilter()..............
2016-01-14 00:04:14,385 INFO TestServlet:42 - ...TestServlet doPost() start..........
2016-01-14 00:04:14,778 INFO TestListener:36 - ......TestListener attributeAdded()......
2016-01-14 00:04:14,974 INFO TestListener:44 - ......TestListener attributeReplaced()......
2016-01-14 00:04:15,342 INFO TestListener:40 - ......TestListener attributeRemoved()......
2016-01-14 00:04:15,904 INFO TestListener:16 - .......TestListener sessionCreated().......
2016-01-14 00:04:17,354 INFO TestListener:20 - .......TestListener sessionDestroyed().......
2016-01-14 00:04:17,815 INFO TestServlet:52 - ...TestServlet doPost() end..........
2016-01-14 00:04:19,044 INFO TestListener:30 - ......TestListener requestDestroyed()......
