log4j2高级应用

依赖配置

<!--排除默认日志配置-->
<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>
<!--引入log4j2依赖-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

基本组件

Logger 日志记录器

如何输出日志，如指定输出方式、设置日志级别、设置日志过滤器等

Appender 日志输出方式

日志输出到什么地方，常用的包括控制台、滚动文件等

• ConsoleAppender
• RollingFileAppender

Layout 日志格式化

根据表达式或JSON格式化日志，如PatternLayout和JsonLayout

日志参数表达式

环境配置参数表达式

Policy 日志滚动规则

• TimeBasedTriggeringPolicy

Strategy 日志删除策略

• DefaultRolloverStrategy

Filter 日志过滤器

过滤器在Configuration、Logger、Appender三种组件中均可以配置

• MarkerFilter 标记过滤
• ThresholdFilter 日志等级过滤
• TimeFilter 时间过滤
• RegexFilter 正则过滤

  Appenders:
    Console: #输出到控制台
      name: Console # Appender 的名字
      target: SYSTEM_OUT
      PatternLayout: #输出格式
        pattern: "%date %level %class %method : %msg%n"
      filters:
        markerFilter: #marker过滤器
          marker: ACCESS_LOGGER
          onMatch: DENY #丢弃
          onMismatch: NEUTRAL #中立
        thresholdFilter: #日志等级过滤器
          level: debug
          onMatch: ACCEPT
          onMismatch: DENY

编程式日志组件

import cn.orange.common.utils.JsonUtils;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.appender.RollingFileAppender;
import org.apache.logging.log4j.core.appender.rolling.DefaultRolloverStrategy;
import org.apache.logging.log4j.core.appender.rolling.TimeBasedTriggeringPolicy;
import org.apache.logging.log4j.core.appender.rolling.action.*;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.filter.MarkerFilter;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.springframework.beans.factory.annotation.Value;

import javax.annotation.PostConstruct;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * 初始化默认日志配置
 */
public class Log4jConfig {

    public static final String ACCESS_LOGGER = "ACCESS_LOGGER";
    @Value("${spring.application.name}")
    private String SERVER_NAME;

    @PostConstruct
    public void init(){
        final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
        final Configuration config = ctx.getConfiguration();

        //日志统一添加字段
        Map<String,String> patternTemplate = new HashMap<>();
        patternTemplate.put("date","%date{yyyy-MM-dd HH:mm:ss.SSS}");
        patternTemplate.put("level","%level");
        patternTemplate.put("traceId","%X{traceId}");
        patternTemplate.put("serverName",SERVER_NAME);
        patternTemplate.put("thread","%thread");
        patternTemplate.put("class","%class");
        patternTemplate.put("method","%method");
        //双引号、换行符、TAB符转义
        patternTemplate.put("message","%replace{%replace{%replace{%message}{\"}{\\\"}}{\r?\n}{\\n}}{\t}{\\t}");
        patternTemplate.put("exception","%replace{%replace{%replace{%xwException}{\"}{\\\"}}{\r?\n}{\\n}}{\t}{\\t}");

        //------------------------------- Appender ----------------------------------
        RollingFileAppender ERROR_ROLLING_FILE = createRollingFileAppender(JsonUtils.beanToJson(patternTemplate) + "%n", "ERROR_ROLLING_FILE", "error",config);
        RollingFileAppender INFO_ROLLING_FILE = createRollingFileAppender(JsonUtils.beanToJson(patternTemplate) + "%n", "INFO_ROLLING_FILE", "info",config);
        RollingFileAppender ACCESS_ROLLING_FILE = createRollingFileAppender("%message%n", "ACCESS_ROLLING_FILE", "access",config);

        ERROR_ROLLING_FILE.start();
        INFO_ROLLING_FILE.start();
        ACCESS_ROLLING_FILE.start();

        //------------------------------- Logger设置 ----------------------------------
        config.getRootLogger().addAppender(ERROR_ROLLING_FILE, Level.ERROR, null);
        //info不需要access日志
        MarkerFilter infoMarkerFilter = MarkerFilter.createFilter(ACCESS_LOGGER, Filter.Result.DENY, Filter.Result.ACCEPT);
        config.getRootLogger().addAppender(INFO_ROLLING_FILE, Level.DEBUG, infoMarkerFilter);
        //只保留access日志
        MarkerFilter accessMarkerFilter = MarkerFilter.createFilter(ACCESS_LOGGER, Filter.Result.ACCEPT, Filter.Result.DENY);
        config.getRootLogger().addAppender(ACCESS_ROLLING_FILE, Level.INFO, accessMarkerFilter);
        ctx.updateLoggers(config);
    }

    /**
     * 创建appender
     * @param pattern   日志表达式
     * @param name      appender名称
     * @param fileName  日志文件名（不包括后缀名，如：info）
     * @param config
     * @return
     */
    private RollingFileAppender createRollingFileAppender(String pattern,String name,String fileName,Configuration config){
        //Layout
        PatternLayout patternLayout = PatternLayout.newBuilder()
                .withAlwaysWriteExceptions(false)
                .withCharset(StandardCharsets.UTF_8)
                .withPattern(pattern)
                .build();

        //日志滚动规则
        TimeBasedTriggeringPolicy timeBasedTriggeringPolicy = TimeBasedTriggeringPolicy.newBuilder().withModulate(true).withInterval(1).build();
        //日志删除策略：7天
        IfFileName ifFileName = IfFileName.createNameCondition(fileName+"-*.log",null,null);
        IfLastModified ifLastModified = IfLastModified.createAgeCondition(Duration.parse("168H"),null);
        PathCondition[] pathConditions = {ifFileName,ifLastModified};
        DeleteAction deleteAction = DeleteAction.createDeleteAction("logs/",false, 1,false,null,pathConditions,null,config);
        Action[] actions = {deleteAction};
        DefaultRolloverStrategy defaultRolloverStrategy = DefaultRolloverStrategy.newBuilder().withCustomActions(actions).build();
        //Appender
        return RollingFileAppender.newBuilder()
                .setName(name)
                .withFileName("logs/"+fileName+".log")
                .withFilePattern("logs/"+fileName+"-%date{yyyy-MM-dd}.log")

                .setLayout(patternLayout)
                .withPolicy(timeBasedTriggeringPolicy)
                .withStrategy(defaultRolloverStrategy)
                .build();
    }
}

分布式追踪日志

1. 通过 servlet 的 Filter 设置 traceId。参考
2. 通过阿里开源的 TransmittableThreadLocal 跨线程存储 traceId。

日志切面

参考地址