一个简单的例子是：
Servlet（根据需要更改日志文件的路径）：
@WebServlet(name = "Log", urlPatterns = { "/log" }) public class LogServlet extends HttpServlet { private static final long serialVersionUID = 7503953988166684851L; public LogServlet() { super(); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { Path path = FileSystems.getDefault() .getPath("/path/to/tomcat/logs", "catalina.out"); StringBuilder logContent = new StringBuilder(); logContent.append("<pre>"); try (BufferedReader reader = Files.newBufferedReader(path, StandardCharsets.UTF_8);) { String line = null; while ((line = reader.readLine()) != null) { logContent.append(line).append("<br/>"); } } catch (IOException x) { // Take care of that } logContent.append("</pre>"); resp.getWriter().print(logContent.toString()); } @Override public void init(ServletConfig servletConfig) throws ServletException { super.init(servletConfig); } }HTML页面：
<!DOCTYPE html><html> <head> <meta charset="UTF-8"> <title>Log viewer</title> <script src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script> <script>window.jQuery || document.write(unescape('%3Cscript src="http://jquery.com/jquery-wp-content/themes/jquery/js/jquery-1.10.2.min.js"%3E%3C/script%3E')) </script> <script type="text/javascript"> var logging = false; function refreshLog() { if (logging) { $.get('/log', function(data) { $('#log').html(data); }); } if (logging) { setTimeout(function() { refreshLog() }, 5000); } } function toggleLogs() { if (logging) { logging = false; $("#tog").val("Start"); } else { logging = true; $("#tog").val("Stop"); refreshLog(); } } </script> </head> <body > <input type="button" id="tog" onclick="toggleLogs()" value="Start" /> <div id="log" ></div> </body></html>
