为Logback日志添加唯一追踪ID

平常在测试的时候，不容易定位报错信息，这个时候给日志加上唯一的追踪ID，查找日志的时候就非常方便了。
像这样：

每个请求打印的日志都会有不同的ID，哪个请求出错，根据ID来定位日志就行了。这个ID还会返回给前端，前端发现报错让后台找原因的话只需要给个ID，后台开发人员就能根据

---

环境：

• SpringBoot - 2.1.5.RELEASE
• JDK8

一、创建过滤器

LogMDCFilter.java

public class LogMDCFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        String requestIdKey = "requestId";
        String requestId = UUID.randomUUID().toString();
        MDC.put(requestIdKey, requestId);

        String levelName = "logLevel";
        String value = servletRequest.getParameter(levelName);
        if (StringUtils.isNotBlank(value)) {
        	//org.slf4j.MDC
            MDC.put(levelName, value.toUpperCase());
        }

        try {
            filterChain.doFilter(servletRequest, servletResponse);
        } finally {
            MDC.remove(requestIdKey);
            MDC.remove(levelName);
        }
    }

    @Override
    public void destroy() {

    }
}

DebugLogTurboFilter.java

public class DebugLogTurboFilter extends TurboFilter {

    @Override
    public FilterReply decide(Marker marker, Logger logger, Level level, String format, Object[] params, Throwable t) {
        int levelInt = level.toInt();
        String levelName = MDC.get("logLevel");
        if (StringUtils.isBlank(levelName) || "DEBUG,INFO,TRACE,WARN".indexOf(levelName) == -1) {
            return FilterReply.NEUTRAL;
        }
        if ((Level.TRACE.levelStr.equals(levelName) && levelInt >= Level.TRACE_INT)
                || (Level.DEBUG.levelStr.equals(levelName) && levelInt >= Level.DEBUG_INT)
                || (Level.INFO.levelStr.equals(levelName) && levelInt >= Level.INFO_INT)
                || (Level.WARN.levelStr.equals(levelName) && levelInt >= Level.WARN_INT)) {
            return FilterReply.ACCEPT;
        }
        return FilterReply.DENY;
    }
}

二、注册过滤器

FilterConfiguration.java

@Configuration
public class FilterConfiguration {

    @Bean
    public FilterRegistrationBean logFilterRegistration() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        //注入过滤器
        registration.setFilter(new LogMDCFilter());
        //拦截规则
        registration.addUrlPatterns("/*");
        //过滤器名称
        registration.setName("logMDCFilter");
        //过滤器顺序
        registration.setOrder(0);
        return registration;
    }
}

三、Logback.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%date{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36}:%line - %msg %X{requestId}%n
            </pattern>
        </encoder>
    </appender>
	//上面的 DebugLogTurboFilter
    <turboFilter class="com.example.common.config.DebugLogTurboFilter">
    </turboFilter>

    <appender name="rollingFile" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>/home/logs/merchant/common-merchant.log</file>
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <fileNamePattern>/home/logs/merchant/history/merchant.%d{yyyy-MM-dd HH}.%i.log</fileNamePattern>
            <maxHistory>30</maxHistory>
            <maxFileSize>3MB</maxFileSize>
        </rollingPolicy>
        <encoder>
            <pattern>%date{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %-5level %logger{36}:%line - %msg %X{requestId}%n
            </pattern>
        </encoder>
    </appender>

    <!-- project default level -->
    <logger name="com.version" level="DEBUG"/>
    <logger name="org.springframework.web.servlet.handler" level="INFO"/>
    <logger name="com.example.user.mapper" level="DEBUG"/>
    <!--log4jdbc -->
    <logger name="org.springframework.jdbc.core.JdbcTemplate" level="INFO"/>

    <root level="INFO">
        <appender-ref ref="console"/>
        <appender-ref ref="rollingFile"/>
    </root>
</configuration>

注意配置中的{requestId}占位符，这个就会替换为生成的唯一日志ID。

四、返回值封装

ResponseModel.java

public class ResponseModel implements Serializable {

    private static final long serialVersionUID = -8972819161141262263L;

    @ApiModelProperty(value = "是否处理成功", name = "success", example = "true")
    private Boolean success;
    @ApiModelProperty(value = "返回码", name = "code", example = "200")
    private Integer code;
    @ApiModelProperty(value = "处理消息", name = "msg", example = "处理成功")
    private String msg;
    @ApiModelProperty(value = "返回数据", name = "data", example = "{}")
    private Object data;
    private String requestId = MDC.get("requestId");
    }

代码写完了，前端每次请求，如果有返回值的话，都会收到唯一日志ID，如图：

可以根据requestId，通过此命令在日志文件中查找对应的日志

cat common-user.log | grep -C 10 f11819ea-6169-4c13-8032-979a88977575