Java for Web学习笔记（四一）：Filter（3）用于Log

下面是一个简单的用于记录请求的URL，请求处理时间的小例子。

在代码中设置Filter

@WebListener public class Configurator implements ServletContextListener { @Override public void contextDestroyed(ServletContextEvent sce) { } @Override public void contextInitialized(ServletContextEvent sce) { ServletContext context = sce.getServletContext(); FilterRegistration.Dynamic registration = context.addFilter("requestLogFilter", new RequestLogFilter()); registration.addMappingForUrlPatterns(null, false, "/*"); } }

Log Filter的代码

public class RequestLogFilter implements Filter { @Override public void init(FilterConfig fConfig) throws ServletException { } @Override public void destroy() { } @Override public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) throws IOException,ServletException { Instant time = Instant.now(); //这里学习一下org.apache.commons.lang3.time.StopWatch的用法，类似于一个秒表计时器，启开，暂停，结束等 StopWatch timer = new StopWatch(); try{ timer.start(); chain.doFilter(request, response); }finally{ //记录servlet的处理情况 timer.stop(); HttpServletRequest in = (HttpServletRequest)request; HttpServletResponse out = (HttpServletResponse)response; //如果是在filter之后的Servlet container（也即web container）进行中设置，检测的值为null String length = out.getHeader("Content-Length"); if(StringUtils.isEmpty(length)) length = "-"; Ststem.out.println(in.getRemoteAddr() + " - - [" + time + "]" + " \"" + in.getMethod() + " " + in.getRequestURI() + " " + in.getProtocol() + "\" " + out.getStatus() + " " + length + " " + timer); } } }

相关链接： 我的Professional Java for Web Applications相关文章