SpringBoot项目使用Log4j2+SLF4J构建日志的方法步骤

<dependencies>
    <!-- Spring Boot Log4j2 Starter -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <!-- 排除掉默认的 logback 依赖 -->
            <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>
</dependencies>

import org.apache.logging.log4j.ThreadContext;
import org.springframework.stereotype.Component;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.UUID;

@Component
public class TraceIdFilter implements Filter {
    
    // 你可以自定义请求头中TraceId的名字
    private static final String TRACE_ID_HEADER = "X-Trace-Id";
    // 这是TraceId在Log4j2 ThreadContext中存储的key
    private static final String TRACE_ID_KEY = "traceId";

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        // 尝试从请求头中获取TraceId，如果没有则生成一个
        String traceId = httpRequest.getHeader(TRACE_ID_HEADER);
        if (traceId == null || traceId.isEmpty()) {
            // 生成唯一ID，这里使用UUID，你可以根据需要调整
            traceId = UUID.randomUUID().toString().replace("-", "").substring(0, 16);
        }

        // 将TraceId放入Log4j2的ThreadContext，这样日志就能自动打印了
        ThreadContext.put(TRACE_ID_KEY, traceId);
        // 可选：将TraceId设置到响应头，方便前端或下游服务追踪
        httpResponse.setHeader(TRACE_ID_HEADER, traceId);

        try {
            chain.doFilter(request, response); // 继续执行请求链
        } finally {
            // 请求处理完毕，务必清理ThreadContext，避免内存泄漏和数据污染
            ThreadContext.remove(TRACE_ID_KEY);
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <!-- 控制台输出配置 -->
        <Console name="Console" target="SYSTEM_OUT">
            <!-- 设置日志输出格式 -->
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level [%X{traceId}] %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Root level="info">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DemoController {
    
    private static final Logger logger = LoggerFactory.getLogger(DemoController.class);
    
    @GetMapping("/test")
    public String testEndpoint() {
        logger.info("收到请求"); // 日志会自动包含traceId
        // ... 你的业务逻辑
        return "请求完成";
    }
}

# application.properties 示例
logging.file.name=/var/log/your-app/application.log

# application.yml 示例
logging:
  file:
    name: /var/log/your-app/application.log

# application.properties 示例
logging.file.path=/var/log/your-app

<!-- logback-spring.xml 示例片段 -->
<configuration>
    <springProperty scope="context" name="LOG_HOME" source="logging.file.path" defaultValue="/tmp/logs"/>
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <!-- 使用在application.properties中设置的logging.file.path -->
        <file>${LOG_HOME}/spring.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- 按天归档日志 -->
            <fileNamePattern>${LOG_HOME}/application.%d{yyyy-MM-dd}.log</fileNamePattern>
            <!-- 保留最多30天的日志历史 -->
            <maxHistory>30</maxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>
    <!-- 其他配置... -->
</configuration>

java -jar your-app.jar --logging.file.name=/path/to/your/logfile.log

export LOGGING_FILE_NAME=/path/to/your/logfile.log
java -jar your-app.jar