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tessl/maven-ch-qos-logback--logback-classic

Comprehensive SLF4J implementation providing enterprise-grade logging with flexible configuration, high performance, and extensive appender ecosystem for Java applications.

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servlet-integration.mddocs/

Servlet Integration

Web application integration components for servlet containers, providing lifecycle management, context initialization, and request-based logging enhancements for Java web applications.

Capabilities

Servlet Context Listener

Servlet container lifecycle integration for proper Logback initialization and cleanup.

/**
 * Servlet context listener for Logback lifecycle management
 */
public class LogbackServletContextListener implements ServletContextListener {
    
    /**
     * Initialize Logback when servlet context starts
     */
    @Override
    public void contextInitialized(ServletContextEvent sce);
    
    /**
     * Cleanup Logback when servlet context stops
     */
    @Override
    public void contextDestroyed(ServletContextEvent sce);
}

Usage Examples:

<!-- web.xml configuration -->
<web-app>
    <listener>
        <listener-class>ch.qos.logback.classic.servlet.LogbackServletContextListener</listener-class>
    </listener>
</web-app>
// Programmatic registration (Servlet 3.0+)
@WebListener
public class MyLogbackListener extends LogbackServletContextListener {
    // Inherits all functionality
}

Servlet Container Initializer

Automatic servlet container initialization using the SPI mechanism.

/**
 * Servlet container initializer for automatic Logback setup
 */
@HandlesTypes({})
public class LogbackServletContainerInitializer implements ServletContainerInitializer {
    
    /**
     * Automatically called by servlet container during startup
     */
    @Override
    public void onStartup(Set<Class<?>> c, ServletContext ctx) throws ServletException;
}

This initializer is automatically discovered and invoked by Servlet 3.0+ containers through the ServiceLoader mechanism, requiring no manual configuration.

Context Selectors for Web Applications

Specialized context selectors for multi-webapp environments.

/**
 * Context detaching servlet context listener for proper cleanup
 */
public class ContextDetachingSCL implements ServletContextListener {
    
    @Override
    public void contextInitialized(ServletContextEvent sce);
    
    @Override
    public void contextDestroyed(ServletContextEvent sce);
}

/**
 * Logger context filter for web applications
 */
public class LoggerContextFilter implements Filter {
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException;
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException;
    
    @Override
    public void destroy();
}

Status Servlet

Web interface for viewing Logback status and configuration information.

/**
 * Servlet for viewing Logback status messages via web interface
 */
public class ViewStatusMessagesServlet extends HttpServlet {
    private static final long serialVersionUID = 443878494348593337L;
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException;
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException;
}

Usage Examples:

<!-- web.xml servlet configuration -->
<servlet>
    <servlet-name>ViewStatusMessages</servlet-name>
    <servlet-class>ch.qos.logback.classic.ViewStatusMessagesServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>ViewStatusMessages</servlet-name>
    <url-pattern>/logback-status</url-pattern>
</servlet-mapping>

MDC Servlet Filter

Servlet filter for automatically populating MDC with request information.

/**
 * Servlet filter that populates MDC with request information
 */
public class MDCInsertingServletFilter implements Filter {
    
    @Override
    public void init(FilterConfig filterConfig) throws ServletException;
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException;
    
    @Override
    public void destroy();
}

This filter automatically adds the following keys to the MDC:

  • req.remoteHost - Remote host address
  • req.userAgent - User agent string
  • req.requestURI - Request URI
  • req.queryString - Query string
  • req.requestURL - Full request URL
  • req.method - HTTP method
  • req.xForwardedFor - X-Forwarded-For header

Usage Examples:

<!-- web.xml filter configuration -->
<filter>
    <filter-name>MDCInsertingFilter</filter-name>
    <filter-class>ch.qos.logback.classic.helpers.MDCInsertingServletFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>MDCInsertingFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>
// Programmatic registration (Servlet 3.0+)
@WebFilter("/*")
public class CustomMDCFilter extends MDCInsertingServletFilter {
    // Can override methods to customize behavior
}

Context Configuration

Web application specific context configuration and initialization.

/**
 * Utility methods for web application context configuration
 */
public class WebLoggerContextUtils {
    
    /**
     * Get the logger context for a web application
     */
    public static LoggerContext getLoggerContext(ServletContext servletContext);
    
    /**
     * Initialize logger context for a web application
     */
    public static void initializeLoggerContext(ServletContext servletContext);
    
    /**
     * Destroy logger context for a web application
     */
    public static void destroyLoggerContext(ServletContext servletContext);
}

Configuration Examples

Complete Web Application Setup

<!-- web.xml - Complete Logback servlet integration -->
<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="3.0">
    
    <!-- Context parameters for Logback configuration -->
    <context-param>
        <param-name>logbackConfigLocation</param-name>
        <param-value>classpath:logback-web.xml</param-value>
    </context-param>
    
    <!-- Logback servlet context listener -->
    <listener>
        <listener-class>ch.qos.logback.classic.servlet.LogbackServletContextListener</listener-class>
    </listener>
    
    <!-- MDC inserting filter (must be first) -->
    <filter>
        <filter-name>MDCInsertingFilter</filter-name>
        <filter-class>ch.qos.logback.classic.helpers.MDCInsertingServletFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>MDCInsertingFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    
    <!-- Status viewing servlet -->
    <servlet>
        <servlet-name>ViewStatusMessages</servlet-name>
        <servlet-class>ch.qos.logback.classic.ViewStatusMessagesServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>ViewStatusMessages</servlet-name>
        <url-pattern>/admin/logback</url-pattern>
    </servlet-mapping>
    
</web-app>

Servlet 3.0+ Annotation-Based Configuration

import ch.qos.logback.classic.servlet.LogbackServletContextListener;
import ch.qos.logback.classic.helpers.MDCInsertingServletFilter;

@WebListener
public class MyLogbackListener extends LogbackServletContextListener {
    // Automatic registration and lifecycle management
}

@WebFilter(filterName = "mdcFilter", urlPatterns = {"/*"})
public class MyMDCFilter extends MDCInsertingServletFilter {
    // Automatic MDC population for all requests
}

@WebServlet(name = "logbackStatus", urlPatterns = {"/admin/logback-status"})
public class MyStatusServlet extends ViewStatusMessagesServlet {
    // Web interface for viewing Logback status
}

Spring Boot Integration

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class LogbackWebConfig {
    
    @Bean
    public ServletListenerRegistrationBean<LogbackServletContextListener> logbackListener() {
        ServletListenerRegistrationBean<LogbackServletContextListener> listener = 
            new ServletListenerRegistrationBean<>();
        listener.setListener(new LogbackServletContextListener());
        return listener;
    }
    
    @Bean
    public FilterRegistrationBean<MDCInsertingServletFilter> mdcFilter() {
        FilterRegistrationBean<MDCInsertingServletFilter> filter = 
            new FilterRegistrationBean<>();
        filter.setFilter(new MDCInsertingServletFilter());
        filter.addUrlPatterns("/*");
        filter.setOrder(1); // Ensure it's first
        return filter;
    }
    
    @Bean
    public ServletRegistrationBean<ViewStatusMessagesServlet> statusServlet() {
        ServletRegistrationBean<ViewStatusMessagesServlet> servlet = 
            new ServletRegistrationBean<>();
        servlet.setServlet(new ViewStatusMessagesServlet());
        servlet.addUrlMappings("/admin/logback-status");
        return servlet;
    }
}

Web-specific Logback Configuration

<!-- logback-web.xml - Web application specific configuration -->
<configuration>
    
    <!-- Use servlet context name in logs -->
    <contextName>${CONTEXT_NAME}</contextName>
    
    <!-- Web-specific appender with request information -->
    <appender name="WEB_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${catalina.base}/logs/webapp.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${catalina.base}/logs/webapp.%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
            <maxFileSize>100MB</maxFileSize>
            <maxHistory>30</maxHistory>
            <totalSizeCap>1GB</totalSizeCap>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} [%X{req.requestURI}] [%X{req.remoteHost}] - %msg%n</pattern>
        </encoder>
    </appender>
    
    <!-- Separate appender for access logs -->
    <appender name="ACCESS_LOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>${catalina.base}/logs/access.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>${catalina.base}/logs/access.%d{yyyy-MM-dd}.log.gz</fileNamePattern>
            <maxHistory>90</maxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} %X{req.remoteHost} "%X{req.method} %X{req.requestURI} %X{req.queryString}" %X{req.userAgent}%n</pattern>
        </encoder>
    </appender>
    
    <!-- Access logger -->
    <logger name="access" level="INFO" additivity="false">
        <appender-ref ref="ACCESS_LOG" />
    </logger>
    
    <!-- Root logger -->
    <root level="INFO">
        <appender-ref ref="WEB_FILE" />
    </root>
    
</configuration>

Usage in Web Application Code

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;

@WebServlet("/user")
public class UserServlet extends HttpServlet {
    private static final Logger logger = LoggerFactory.getLogger(UserServlet.class);
    private static final Logger accessLogger = LoggerFactory.getLogger("access");
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException {
        
        // MDC is automatically populated by MDCInsertingServletFilter
        // Additional custom MDC values can be added
        String userId = req.getParameter("userId");
        if (userId != null) {
            MDC.put("userId", userId);
        }
        
        try {
            logger.info("Processing user request");
            
            // Business logic here
            processUserRequest(req, resp);
            
            // Access log entry
            accessLogger.info("Request processed successfully");
            
        } catch (Exception e) {
            logger.error("Error processing user request", e);
            resp.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
        } finally {
            // Clean up custom MDC values
            MDC.remove("userId");
            // Note: Request-related MDC values are automatically cleaned up
        }
    }
    
    private void processUserRequest(HttpServletRequest req, HttpServletResponse resp) {
        // Implementation
    }
}

Context Separation in Multi-Webapp Environment

// Custom context selector for webapp isolation
public class WebAppContextSelector extends ContextJNDISelector {
    
    @Override
    public LoggerContext getLoggerContext() {
        // Return context specific to current web application
        return getLoggerContext(getCurrentWebAppName());
    }
    
    private String getCurrentWebAppName() {
        // Implementation to determine current webapp context
        return Thread.currentThread().getContextClassLoader().toString();
    }
}

// System property to enable custom selector
// -Dlogback.ContextSelector=com.example.WebAppContextSelector

This servlet integration provides:

  1. Automatic Lifecycle Management - Proper initialization and cleanup of Logback contexts
  2. Request Context Logging - Automatic population of request-related information in MDC
  3. Web Interface - Status servlet for monitoring and debugging
  4. Multi-Webapp Support - Context isolation in enterprise environments
  5. Container Integration - Seamless integration with servlet containers like Tomcat, Jetty, etc.

Install with Tessl CLI

npx tessl i tessl/maven-ch-qos-logback--logback-classic

docs

appenders.md

configuration.md

core-logging.md

encoders-layouts.md

filters.md

index.md

network-logging.md

servlet-integration.md

tile.json