code: ///////////////////////////////////////////////////////////////////////////////////////////////
  // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
  // Copyright (C) 2001-2023 the original author or authors.
  //
  // This library is free software; you can redistribute it and/or
  // modify it under the terms of the GNU Lesser General Public
  // License as published by the Free Software Foundation; either
  // version 2.1 of the License, or (at your option) any later version.
  //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle;
  
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.PrintWriter;
  import java.io.Writer;
  import java.nio.charset.StandardCharsets;
  
  import com.puppycrawl.tools.checkstyle.api.AuditEvent;
  import com.puppycrawl.tools.checkstyle.api.AuditListener;
  import com.puppycrawl.tools.checkstyle.api.SeverityLevel;
  
  /**
   * Simple logger for metadata generator util.
   */
  public class MetadataGeneratorLogger extends AbstractAutomaticBean implements AuditListener {
  
      /**
       * Where to write error messages.
       */
      private final PrintWriter errorWriter;
  
      /**
       * Formatter for the log message.
       */
      private final AuditEventFormatter formatter;
  
      /**
       * Close output stream in audit finished.
       */
      private final boolean closeErrorWriter;
  
      /**
       * Creates a new MetadataGeneratorLogger instance.
       *
       * @param outputStream where to log audit events
       * @param outputStreamOptions if {@code CLOSE} error should be closed in auditFinished()
       */
      public MetadataGeneratorLogger(OutputStream outputStream,
              OutputStreamOptions outputStreamOptions) {
          final Writer errorStreamWriter = new OutputStreamWriter(outputStream,
                  StandardCharsets.UTF_8);
          errorWriter = new PrintWriter(errorStreamWriter);
          formatter = new AuditEventDefaultFormatter();
          closeErrorWriter = outputStreamOptions == OutputStreamOptions.CLOSE;
      }
  
      @Override
      public void auditStarted(AuditEvent event) {
          errorWriter.flush();
      }
  
      @Override
      public void auditFinished(AuditEvent event) {
          errorWriter.flush();
          if (closeErrorWriter) {
              errorWriter.close();
          }
      }
  
      @Override
      public void fileStarted(AuditEvent event) {
          // No code by default.
      }
  
      @Override
      public void fileFinished(AuditEvent event) {
          errorWriter.flush();
      }
  
      @Override
      public void addError(AuditEvent event) {
          final SeverityLevel severityLevel = event.getSeverityLevel();
          if (severityLevel != SeverityLevel.IGNORE) {
              final String errorMessage = formatter.format(event);
              errorWriter.println(errorMessage);
          }
      }
  
      @Override
      public void addException(AuditEvent event, Throwable throwable) {
          synchronized (errorWriter) {
              throwable.printStackTrace(errorWriter);
          }
      }
  
      @Override
      protected void finishLocalSetup() {
          // No code by default.
      }
  }
  