Spring MVC 集成 Logback

• 引用slf4j和logback的依賴，尤其是logback-ext-spring，是Logback對於Spring的擴展：

<!-- Logging begin -->
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>${slf4j.version}</version>
</dependency>
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>${logback.version}</version>
</dependency>
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-core</artifactId>
    <version>${logback.version}</version>
</dependency>
<dependency>
    <groupId>org.logback-extensions</groupId>
    <artifactId>logback-ext-spring</artifactId>
    <version>${logback-ext-spring.version}</version>
</dependency>
<!-- Logging end -->

• 定義Listener，作用是在項目啓動時初始化Logback組件：

import ch.qos.logback.ext.spring.web.WebLogbackConfigurer;

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

public class LogbackListener implements ServletContextListener {

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        // 注入系統變量，可以在logback.xml中引用
        System.setProperty("customSystemProperty", "xxx");

        WebLogbackConfigurer.initLogging(sce.getServletContext());
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        WebLogbackConfigurer.shutdownLogging(sce.getServletContext());
    }
}

• 在web.xml中聲明LogbackListener，可指定logback.xml文件的路徑：

<context-param>
    <param-name>logbackConfigLocation</param-name>
    <param-value>classpath:logback.xml</param-value>
</context-param>

<listener>
    <listener-class>com.yjy.listener.LogbackListener</listener-class>
</listener>

• 自定義logback.xml，聲明日誌格式、存放路徑等：

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
    <property name="LOG_HOME" value="/export/logs/spring-framework-demo/" />
    <property name="APP_NAME" value="spring-framework-demo" />

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <!-- 此處引用了LogbackListener中注入的系統變量 -->
            <pattern>${APP_NAME}-${customSystemProperty}: %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %p - %c %method %m%n</pattern>
        </encoder>
    </appender>
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <FileNamePattern>${LOG_HOME}${APP_NAME}.%d{yyyy-MM-dd}.log.gz</FileNamePattern>
            <!-- 日誌文件保留天數 -->
            <MaxHistory>30</MaxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>${APP_NAME}: %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %p - %c %method %m%n</pattern>
        </encoder>
    </appender>

    <root>
        <level value="INFO" />
        <appender-ref ref="STDOUT" />
        <appender-ref ref="FILE" />
    </root>
</configuration>