Zhuoli's Blog上篇文章Spring Boot日志管理，我简单讲述了Spring Boot中使用默认日志Logback进行日志管理的配置。在上篇文章中有讲到，LogBack是Log4j的改良版本，比Log4j拥有更多的特性，同时也带来很大性能提升。但是log4j作为一款常用的日志库，在实际开发中还是很常用的，本片文章，我将简单介绍一下Spring Boot中如何使用Log4J进行日志管理。
创建Spring Boot工程时，必然会引入了spring-boot-starter，其中包含了spring-boot-starter-logging，该依赖内容就是Spring Boot默认的日志框架Logback，所以我们在引入log4j之前，首先要先排除该包的依赖，再引入log4j的依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>在src/main/resuorces文件夹添加log4j配置文件log4j2.xml：
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
<Property name="LOG_PATTERN">
%d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${hostName} --- [%15.15t] %-40.40c{1.} : %m%n%ex
</Property>
</Properties>
<Appenders>
<Console name="ConsoleAppender" target="SYSTEM_OUT" follow="true">
<PatternLayout pattern="${LOG_PATTERN}"/>
</Console>
</Appenders>
<Loggers>
<Logger name="com.example.log4j2demo" level="debug" additivity="false">
<AppenderRef ref="ConsoleAppender"/>
</Logger>
<Root level="info">
<AppenderRef ref="ConsoleAppender"/>
</Root>
</Loggers>
</Configuration>log4J也可以和SLF4J配合使用，实现运行时绑定log4J实例，使用方法与上一篇文章logback一致。
@RestController
@RequestMapping(value = "/health")
public class HealthCheckController {
private final Logger logger = LoggerFactory.getLogger(Object.class);
@RequestMapping(value = "/check", method = RequestMethod.GET)
public String check(){
logger.trace("health check controller trace……");
logger.debug("health check controller debug……");
logger.info("health check controller info……");
logger.warn("health check controller warn……");
logger.error("health check controller error……");
return "ok";
}
}-
Log4j文件输出配置
在Logback中可以通过配置RollingFile子节点达到文件输出的目的，配置如下：
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
<Property name="LOG_PATTERN">
%d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${hostName} --- [%15.15t] %-40.40c{1.} : %m%n%ex
</Property>
</Properties>
<Appenders>
<Console name="ConsoleAppender" target="SYSTEM_OUT" follow="true">
<PatternLayout pattern="${LOG_PATTERN}"/>
</Console>
<RollingFile name="FileAppender" fileName="d:/log/log4j2-demo.log"
filePattern="d:/log/log4j2-demo-%d{yyyy-MM-dd}-%i.log">
<PatternLayout>
<Pattern>${LOG_PATTERN}</Pattern>
</PatternLayout>
<Policies>
<SizeBasedTriggeringPolicy size="10MB" />
</Policies>
<DefaultRolloverStrategy max="10"/>
</RollingFile>
</Appenders>
<Loggers>
<Logger name="com.zhuoli.service.springboot.log4j" level="debug" additivity="false">
<AppenderRef ref="ConsoleAppender" />
</Logger>
<Root level="info">
<AppenderRef ref="ConsoleAppender" />
<AppenderRef ref="FileAppender" />
</Root>
</Loggers>
</Configuration>-
Log4j异步日志
log4j启动异步需要lmax支持，需要引入jar包：
<!-- Needed for Async Logging with Log4j 2 -->
<dependency>
<groupId>com.lmax</groupId>
<artifactId>disruptor</artifactId>
<version>3.3.6</version>
</dependency>修改日志输出为异步：
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
<Property name="LOG_PATTERN">
%d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${hostName} --- [%15.15t] %-40.40c{1.} : %m%n%ex
</Property>
</Properties>
<Appenders>
<Console name="ConsoleAppender" target="SYSTEM_OUT" follow="true">
<PatternLayout pattern="${LOG_PATTERN}"/>
</Console>
<RollingFile name="FileAppender" fileName="d:/log/log4j2-demo.log"
filePattern="d:/log/log4j2-demo-%d{yyyy-MM-dd}-%i.log">
<PatternLayout>
<Pattern>${LOG_PATTERN}</Pattern>
</PatternLayout>
<Policies>
<SizeBasedTriggeringPolicy size="10MB" />
</Policies>
<DefaultRolloverStrategy max="10"/>
</RollingFile>
<!--file异步输出-->
<Async name="AsyncFile" buffersize="32768" blocking="false">
<AppenderRef ref="FileAppender"/>
</Async>
<!--console异步输出-->
<Async name="AsyncConsole" buffersize="32768" blocking="false">
<AppenderRef ref="ConsoleAppender"/>
</Async>
</Appenders>
<Loggers>
<Logger name="org.apache.catalina.startup.DigesterFactory" level="error"/>
<Logger name="org.apache.catalina.util.LifecycleBase" level="error"/>
<Logger name="org.apache.coyote.http11.Http11NioProtocol" level="warn"/>
<logger name="org.apache.sshd.common.util.SecurityUtils" level="warn"/>
<Logger name="org.apache.tomcat.util.net.NioSelectorPool" level="warn"/>
<Logger name="org.crsh.plugin" level="warn"/>
<logger name="org.crsh.ssh" level="warn"/>
<Logger name="org.eclipse.jetty.util.component.AbstractLifeCycle" level="error"/>
<Logger name="org.hibernate.validator.internal.util.Version" level="warn"/>
<logger name="org.springframework.boot.actuate.autoconfigure.CrshAutoConfiguration" level="warn"/>
<logger name="org.springframework.boot.actuate.endpoint.jmx" level="warn"/>
<logger name="org.thymeleaf" level="warn"/>
<logger name="org.springframework.context.support" level="warn"/>
<logger name="org.springframework.jmx.export.annotation" level="warn"/>
<logger name="com.zaxxer.hikari" level="warn"/>
<logger name="org.springframework.context.annotation.AnnotationConfigApplicationContext" level="warn"/>
<logger name="org.springframework.web.servlet.mvc.method.annotation" level="warn"/>
<logger name="metrics_influxdb.measurements" level="off"/>
<Root level="info">
<AppenderRef ref="AsyncConsole" />
<AppenderRef ref="AsyncFile" />
</Root>
</Loggers>
</Configuration>上述配置实现了日志异步输出，及区别包进行不同级别的log输出，在日常开发中基本是可用的。通过本片文章可以看出，其实log4j配置和logback配置是相通的，建议想了解日志配置的同学花时间去看一下上篇Spring Boot日志管理的文章。另外，在生产上，通过kafaka异步日志输出也是非常常见的，想了解的同学可以看一下这一篇文章Kafka+Log4j实现日志集中管理
示例代码：码云 – 卓立 – Spring Boot + log4j日志配置
参考链接：