springboot 添加全局日志追踪traceId

import org.slf4j.MDC;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.UUID;

@Component
@Order(ordered.HIGHEST_PRECEDENCE)
public class TraceIdFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        
        String traceId = UUID.randomUUID().toString().substring(0, 8);
        MDC.put("traceId", traceId); // key 必须是 "traceId"

        try {
            chain.doFilter(request, response);
        } finally {
            MDC.clear(); // 清理！
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- 控制台输出 -->
    <appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level [%X{traceId}] %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- 文件输出（可选） -->
    <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>logs/app.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <fileNamePattern>logs/app.%d{yyyy-MM-dd}.%i.log</fileNamePattern>
            <maxFileSize>100MB</maxFileSize>
            <maxHistory>30</maxHistory>
        </rollingPolicy>
        <encoder>
            <pattern>%d{HH:mm:ss} [%thread] %-5level [%X{traceId}] %logger - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- 根日志级别 -->
    <root level="INFO">
        <appender-ref ref="CONSOLE"/>
        <appender-ref ref="FILE"/>
    </root>

</configuration>

@RestController
public class TestController {
    private static final Logger log = LoggerFactory.getLogger(TestController.class);

    @GetMapping("/test")
    public String test() {
        log.info("Hello from controller");
        return "OK";
    }
}

16:45:00 [a1b2c3d4] Hello from controller