logback + slf4j + jboss + spring mvc

logback、log4j、log4j2 全是以同一个人为首的团伙搞出来的（日志专业户！），这几个各有所长，log4j性能相对最差，log4j2性能不错，但是目前跟mybatis有些犯冲(log4j2的当前版本，已经将AbstractLoggerWrapper更名成ExtendedLoggerWrapper，但是mybatis 2.3.7依赖的仍然是旧版本的log4j2，所以mybatis使用log4j2会报错)，说到日志，还要注意另一外项目SLF4J( java的世界里，记日志的组件真是多!)，SLF4J只一个接口标准，并不提供实现（就好象JSF/JPA 与 RichFaces/Hibernate的关系类似），而LogBack是SLF4J的一个实现，下面介绍logback的基本用法

一、基本用法

1.1 maven依赖项

         <!-- log -->
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
             <version>1.7.7</version>
         </dependency>

         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-core</artifactId>
             <version>1.1.2</version>
         </dependency>

         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
             <version>1.1.2</version>
         </dependency>

1.2 配置文件logback.xml

 <?xml version="1.0" encoding="UTF-8" ?>
 <configuration scan="true" scanPeriod="1800 seconds"
     debug="false">

     <property name="USER_HOME" value="logs" />
     <property scope="context" name="FILE_NAME" value="mylog-logback" />

     <timestamp key="byDay" datePattern="yyyy-MM-dd" />

     <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
         <encoder>
             <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
             </pattern>
         </encoder>
     </appender>

     <appender name="file"
         class="ch.qos.logback.core.rolling.RollingFileAppender">
         <file>${USER_HOME}/${FILE_NAME}.log</file>

         <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
             <fileNamePattern>${USER_HOME}/${byDay}/${FILE_NAME}-${byDay}-%i.log.zip
             </fileNamePattern>
             <minIndex>1</minIndex>
             <maxIndex>10</maxIndex>
         </rollingPolicy>

         <triggeringPolicy
             class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
             <maxFileSize>5MB</maxFileSize>
         </triggeringPolicy>
         <encoder>
             <pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
             </pattern>
         </encoder>

     </appender>

     <logger name="com.cnblogs.yjmyzz.App2" level="debug" additivity="true">
         <appender-ref ref="file" />
         <!-- <appender-ref ref="STDOUT" /> -->
     </logger>

     <root level="info">
         <appender-ref ref="STDOUT" />
     </root>
 </configuration>

1.3 示例程序
跟前面log4j2的示例程序几乎完全一样：

 package com.cnblogs.yjmyzz;

 import org.slf4j.*;

 public class App2 {

     static Logger logger = LoggerFactory.getLogger(App2.class);

     public static void main(String[] args) {
         for (int i = 0; i < 100000; i++) {
             logger.trace("trace message " + i);
             logger.debug("debug message " + i);
             logger.info("info message " + i);
             logger.warn("warn message " + i);
             logger.error("error message " + i);
         }
         System.out.println("Hello World! 2");
     }
 }

运行后，会在当前目录下创建logs目录，生成名为mylog-logback.log的日志文件，该文件体积>5M后，会自动创建 yyyy-mm-dd的目录，将历史日志打包生成类似：mylog-logback-2014-09-24-1.log.zip 的压缩包，每天最多保留10个

二、与spring -mvc的集成 

2.1 maven依赖项

注：${springframework.version}，我用的是3.2.8.RELEASE 版本

 <!-- Spring -->
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-core</artifactId>
             <version>${springframework.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-beans</artifactId>
             <version>${springframework.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-context</artifactId>
             <version>${springframework.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-web</artifactId>
             <version>${springframework.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-webmvc</artifactId>
             <version>${springframework.version}</version>
         </dependency>
         <dependency>
             <groupId>org.springframework</groupId>
             <artifactId>spring-expression</artifactId>
             <version>${springframework.version}</version>
         </dependency>

         <!-- logback -->
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
             <version>1.7.7</version>
         </dependency>        

         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-core</artifactId>
             <version>1.1.2</version>
         </dependency>

         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
             <version>1.1.2</version>
         </dependency>

         <!-- Servlet -->
         <dependency>
             <groupId>javax.servlet</groupId>
             <artifactId>servlet-api</artifactId>
             <version>2.5</version>
             <scope>provided</scope>
         </dependency>

2.2 web.xml里增加下面的内容

 <!-- logback-begin -->
     <context-param>
         <param-name>logbackConfigLocation</param-name>
         <param-value>classpath:logback.xml</param-value>
     </context-param>
     <listener>
         <listener-class>com.cnblogs.yjmyzz.util.LogbackConfigListener</listener-class>
     </listener>
     <!-- logback-end -->

其中com.cnblogs.yjmyzz.util.LogbackConfigListener 是自己开发的类，代码如下：(从网上掏来的)

注：该处理方式同样适用于struts 2.x

 package com.cnblogs.yjmyzz.util;

 import javax.servlet.ServletContextEvent;
 import javax.servlet.ServletContextListener;

 public class LogbackConfigListener implements ServletContextListener {

     public void contextInitialized(ServletContextEvent event) {
         LogbackWebConfigurer.initLogging(event.getServletContext());
     }

     public void contextDestroyed(ServletContextEvent event) {
         LogbackWebConfigurer.shutdownLogging(event.getServletContext());
     }
 }

LogbackConfigListener

 package com.cnblogs.yjmyzz.util;

 import java.io.FileNotFoundException;

 import javax.servlet.ServletContext;

 import org.springframework.util.ResourceUtils;
 import org.springframework.util.SystemPropertyUtils;
 import org.springframework.web.util.WebUtils;

 public abstract class LogbackWebConfigurer {

     /** Parameter specifying the location of the logback config file */
     public static final String CONFIG_LOCATION_PARAM = "logbackConfigLocation";

     /**
      * Parameter specifying the refresh interval for checking the logback config
      * file
      */
     public static final String REFRESH_INTERVAL_PARAM = "logbackRefreshInterval";

     /** Parameter specifying whether to expose the web app root system property */
     public static final String EXPOSE_WEB_APP_ROOT_PARAM = "logbackExposeWebAppRoot";

     /**
      * Initialize logback, including setting the web app root system property.
      *
      * @param servletContext
      *            the current ServletContext
      * @see WebUtils#setWebAppRootSystemProperty
      */
     public static void initLogging(ServletContext servletContext) {
         // Expose the web app root system property.
         if (exposeWebAppRoot(servletContext)) {
             WebUtils.setWebAppRootSystemProperty(servletContext);
         }

         // Only perform custom logback initialization in case of a config file.
         String location = servletContext
                 .getInitParameter(CONFIG_LOCATION_PARAM);
         if (location != null) {
             // Perform actual logback initialization; else rely on logback's
             // default initialization.
             try {
                 // Return a URL (e.g. "classpath:" or "file:") as-is;
                 // consider a plain file path as relative to the web application
                 // root directory.
                 if (!ResourceUtils.isUrl(location)) {
                     // Resolve system property placeholders before resolving
                     // real path.
                     location = SystemPropertyUtils
                             .resolvePlaceholders(location);
                     location = WebUtils.getRealPath(servletContext, location);
                 }

                 // Write log message to server log.
                 servletContext.log("Initializing logback from [" + location
                         + "]");

                 // Initialize without refresh check, i.e. without logback's
                 // watchdog thread.
                 LogbackConfigurer.initLogging(location);

             } catch (FileNotFoundException ex) {
                 throw new IllegalArgumentException(
                         "Invalid 'logbackConfigLocation' parameter: "
                                 + ex.getMessage());
             }
         }
     }

     /**
      * Shut down logback, properly releasing all file locks and resetting the
      * web app root system property.
      *
      * @param servletContext
      *            the current ServletContext
      * @see WebUtils#removeWebAppRootSystemProperty
      */
     public static void shutdownLogging(ServletContext servletContext) {
         servletContext.log("Shutting down logback");
         try {
             LogbackConfigurer.shutdownLogging();
         } finally {
             // Remove the web app root system property.
             if (exposeWebAppRoot(servletContext)) {
                 WebUtils.removeWebAppRootSystemProperty(servletContext);
             }
         }
     }

     /**
      * Return whether to expose the web app root system property, checking the
      * corresponding ServletContext init parameter.
      *
      * @see #EXPOSE_WEB_APP_ROOT_PARAM
      */
     private static boolean exposeWebAppRoot(ServletContext servletContext) {
         String exposeWebAppRootParam = servletContext
                 .getInitParameter(EXPOSE_WEB_APP_ROOT_PARAM);
         return (exposeWebAppRootParam == null || Boolean
                 .valueOf(exposeWebAppRootParam));
     }

 }

LogbackWebConfigurer

 package com.cnblogs.yjmyzz.util;

 import java.io.File;
 import java.io.FileNotFoundException;
 import java.net.URL;

 import org.slf4j.LoggerFactory;
 import org.springframework.util.ResourceUtils;
 import org.springframework.util.SystemPropertyUtils;

 import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.joran.JoranConfigurator;
 import ch.qos.logback.core.joran.spi.JoranException;

 public abstract class LogbackConfigurer {

     /** Pseudo URL prefix for loading from the class path: "classpath:" */
     public static final String CLASSPATH_URL_PREFIX = "classpath:";

     /** Extension that indicates a logback XML config file: ".xml" */
     public static final String XML_FILE_EXTENSION = ".xml";

     private static LoggerContext lc = (LoggerContext) LoggerFactory
             .getILoggerFactory();
     private static JoranConfigurator configurator = new JoranConfigurator();

     /**
      * Initialize logback from the given file location, with no config file
      * refreshing. Assumes an XML file in case of a ".xml" file extension, and a
      * properties file otherwise.
      *
      * @param location
      *            the location of the config file: either a "classpath:"
      *            location (e.g. "classpath:mylogback.properties"), an absolute
      *            file URL (e.g.
      *            "file:C:/logback.properties), or a plain absolute path in the file system (e.g. "
      *            C:/logback.properties")
      * @throws FileNotFoundException
      *             if the location specifies an invalid file path
      */
     public static void initLogging(String location)
             throws FileNotFoundException {
         String resolvedLocation = SystemPropertyUtils
                 .resolvePlaceholders(location);
         URL url = ResourceUtils.getURL(resolvedLocation);
         if (resolvedLocation.toLowerCase().endsWith(XML_FILE_EXTENSION)) {
             // DOMConfigurator.configure(url);
             configurator.setContext(lc);
             lc.reset();
             try {
                 configurator.doConfigure(url);
             } catch (JoranException ex) {
                 throw new FileNotFoundException(url.getPath());
             }
             lc.start();
         }
         // else {
         // PropertyConfigurator.configure(url);
         // }
     }

     /**
      * Shut down logback, properly releasing all file locks.
      * <p>
      * This isn't strictly necessary, but recommended for shutting down logback
      * in a scenario where the host VM stays alive (for example, when shutting
      * down an application in a J2EE environment).
      */
     public static void shutdownLogging() {
         lc.stop();
     }

     /**
      * Set the specified system property to the current working directory.
      * <p>
      * This can be used e.g. for test environments, for applications that
      * leverage logbackWebConfigurer's "webAppRootKey" support in a web
      * environment.
      *
      * @param key
      *            system property key to use, as expected in logback
      *            configuration (for example: "demo.root", used as
      *            "${demo.root}/WEB-INF/demo.log")
      * @see org.springframework.web.util.logbackWebConfigurer
      */
     public static void setWorkingDirSystemProperty(String key) {
         System.setProperty(key, new File("").getAbsolutePath());
     }

 }

LogbackConfigurer

2.3 JBOSS EAP 6+ 的特殊处理

jboss 默认已经集成了sf4j模块，会与上面新加的3个类有冲突，app启动时会报错：

java.lang.ClassCastException: org.slf4j.impl.Slf4jLoggerFactory cannot be cast to ch.qos.logback.classic.LoggerContext

所以，需要手动排除掉jboss默认的slf4j模块，在web-inf下创建名为jboss-deployment-structure.xml的文件，内容如下：

 <?xml version="1.0" encoding="UTF-8"?>
 <jboss-deployment-structure>
     <deployment>
         <exclusions>
             <module name="org.slf4j" />
             <module name="org.slf4j.impl" />
             <module name="org.slf4j.jcl-over-slf4j" />
             <module name="org.slf4j.ext" />
         </exclusions>
     </deployment>
 </jboss-deployment-structure>

2.4 最后将logback.xml放到resouces目录下即可(打包后，会自动复制到classpath目录下)