Is there a way to view my web-apps tomcat logs in

I am using log4j to log my data. I wan to be able to view the log files realtime alongside my web-app in a browser. There are standalone tools like Chainsaw which are quite good, but they don't serve the purpos eof viewing logs real-time in a browser.

Can anybody help me with this?

回答1:

A simple example would be:

Servlet (change path of log file as needed):

@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 page:

<!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 style="width: 100%; padding: 0; margin: 0">
  <input type="button" id="tog" onclick="toggleLogs()" value="Start" />
  <div id="log" style="width: 100%; padding: 0; margin: 0"></div>
 </body>
</html>

回答2:

You can use psi-probe. It has a built-in functionality to access logs in real-time, change log level, download, etc...