feat(TeeFilter): Remove printing stacktraces in the filter

The filter should not print the Stacktrace and then rethrow the exceptions.
Other handlers will handle the Servlet Exceptions anyways.

Additionally allow users to overwrite the logging output method in the filter.

Signed-off-by: flx5 <1330854+flx5@users.noreply.github.com>

Author: flx5

common/src/main/java/ch/qos/logback/access/common/servlet/TeeFilter.java

@@ -43,29 +43,20 @@ public void doFilter(ServletRequest request, ServletResponse response, FilterCha
             throws IOException, ServletException {
 
         if (active && request instanceof HttpServletRequest) {
-            try {
-                TeeHttpServletRequest teeRequest = new TeeHttpServletRequest((HttpServletRequest) request);
-                TeeHttpServletResponse teeResponse = new TeeHttpServletResponse((HttpServletResponse) response);
+            TeeHttpServletRequest teeRequest = new TeeHttpServletRequest((HttpServletRequest) request);
+            TeeHttpServletResponse teeResponse = new TeeHttpServletResponse((HttpServletResponse) response);
 
-                // System.out.println("BEFORE TeeFilter. filterChain.doFilter()");
+            try {
                 filterChain.doFilter(teeRequest, teeResponse);
-                // System.out.println("AFTER TeeFilter. filterChain.doFilter()");
-
+            } finally {
                 teeResponse.finish();
                 // let the output contents be available for later use by
                 // logback-access-logging
                 teeRequest.setAttribute(AccessConstants.LB_OUTPUT_BUFFER, teeResponse.getOutputBuffer());
-            } catch (IOException e) {
-                e.printStackTrace();
-                throw e;
-            } catch (ServletException e) {
-                e.printStackTrace();
-                throw e;
             }
         } else {
             filterChain.doFilter(request, response);
         }
-
     }
 
     @Override
@@ -76,9 +67,9 @@ public void init(FilterConfig filterConfig) throws ServletException {
 
         active = computeActivation(localhostName, includeListAsStr, excludeListAsStr);
         if (active)
-            System.out.println("TeeFilter will be ACTIVE on this host [" + localhostName + "]");
+            logInfo("TeeFilter will be ACTIVE on this host [" + localhostName + "]");
         else
-            System.out.println("TeeFilter will be DISABLED on this host [" + localhostName + "]");
+            logInfo("TeeFilter will be DISABLED on this host [" + localhostName + "]");
 
     }
 
@@ -101,13 +92,13 @@ public static List<String> extractNameList(String nameListAsStr) {
         return nameList;
     }
 
-    static String getLocalhostName() {
+    String getLocalhostName() {
         String hostname = "127.0.0.1";
 
         try {
             hostname = InetAddress.getLocalHost().getHostName();
         } catch (UnknownHostException uhe) {
-            uhe.printStackTrace();
+            logWarn("Unknown host", uhe);
         }
         return hostname;
     }
@@ -132,4 +123,26 @@ static boolean mathesExcludesList(String hostname, List<String> excludesList) {
         return excludesList.contains(hostname);
     }
 
+    /**
+     * Log a warning.
+     *
+     * Can be overwritten to use a logger.
+     *
+     * @param msg The message.
+     * @param ex The exception.
+     */
+    protected void logWarn(String msg, Throwable ex) {
+        System.err.println(msg + ": " + ex);
+    }
+
+    /**
+     * Log an info message.
+     *
+     * Can be overwritten to use a logger.
+     *
+     * @param msg The message to log.
+     */
+    protected void logInfo(String msg) {
+        System.out.println(msg);
+    }
 }

tomcat_11_0_blackbox/src/main/java/ch/qos/logback/access/tomcat_11_0/EmbeddedTomcatTest.java

@@ -1,12 +1,15 @@
 package ch.qos.logback.access.tomcat_11_0;
 
+import ch.qos.logback.access.common.servlet.TeeFilter;
 import ch.qos.logback.access.common.spi.IAccessEvent;
 import ch.qos.logback.access.tomcat.LogbackValve;
 import org.apache.catalina.Context;
 import org.apache.catalina.LifecycleException;
 import org.apache.catalina.Server;
 import org.apache.catalina.connector.Connector;
 import org.apache.catalina.startup.Tomcat;
+import org.apache.tomcat.util.descriptor.web.FilterDef;
+import org.apache.tomcat.util.descriptor.web.FilterMap;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -31,7 +34,6 @@ public class EmbeddedTomcatTest {
 
     @BeforeEach
     public void embed() throws LifecycleException {
-
         tomcat.setBaseDir("/tmp");
         //tomcat.setPort(port);
         Connector connector = tomcat.getConnector();
@@ -40,6 +42,16 @@ public void embed() throws LifecycleException {
         String contextPath = "";
         String docBase = new File(".").getAbsolutePath();
         Context context = tomcat.addContext(contextPath, docBase);
+        FilterDef filterDef = new FilterDef();
+        filterDef.setFilterName(TeeFilter.class.getSimpleName());
+        filterDef.setFilterClass(TeeFilter.class.getName());
+        context.addFilterDef(filterDef);
+
+        FilterMap myFilterMap = new FilterMap();
+        myFilterMap.setFilterName(TeeFilter.class.getSimpleName());
+        myFilterMap.addURLPattern("/*");
+        context.addFilterMap(myFilterMap);
+
         String servletName = "SampleServlet";
         String urlPattern = "/*";