logback + MDC 搭建 springboot 的日志系统

灰太狼 2021-01-19 16:55 574阅读 0赞

#### 前言： ####

日志的作用是什么？调试，问题定位，数据分析。日志很重要，要保证统一的样式，分级别，请求可追溯。

##### 1. springboot 自带的logback #####

如果你是 ieda 开发工具，并且是maven工程，  
可以点开 pom 文件，右键 -> maven -> Show Dependencies ，可以查看整个项目的依赖关系，其中有 logback  
![logback][]

##### 2.配置 logback.xml 文件 #####

这个文件配置好放在 resources 目录下即可（不需要其他任何地方的配置），工程可自动识别，仔细阅读文件注解。

<?xml version="1.0" encoding="UTF-8"?>
    <configuration debug="false">
        
        <contextName>${APP_NAME}</contextName>
        
        <property name="LOG_HOME" value="./logs" />
        <property name="APP_NAME" value="log"/>
        
        <property name="LOG_PATTERN" value="%d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] [%X{requestId}]  %-5level %logger{50} - %msg%n"/>
    
        
        <appender name="consoleLog" class="ch.qos.logback.core.ConsoleAppender">
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>${LOG_PATTERN}</pattern>
            </encoder>
        </appender>
    
        <appender name="fileInfoLog"  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>INFO</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                
                <FileNamePattern>${LOG_HOME}/${APP_NAME}.info.log.%d{yyyy-MM-dd}.log</FileNamePattern>
                
                <MaxHistory>30</MaxHistory>
                <totalSizeCap>30MB</totalSizeCap>
            </rollingPolicy>
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>${LOG_PATTERN}</pattern>
            </encoder>
        </appender>
    
        <appender name="fileErrorLog"  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>ERROR</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                
                <FileNamePattern>${LOG_HOME}/${APP_NAME}.error.log.%d{yyyy-MM-dd}.log</FileNamePattern>
                
                <MaxHistory>10</MaxHistory>
                <totalSizeCap>8MB</totalSizeCap>
            </rollingPolicy>
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>${LOG_PATTERN}</pattern>
            </encoder>
        </appender>
    
        <appender name="fileWarnLog"  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>WARN</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                
                <FileNamePattern>${LOG_HOME}/${APP_NAME}.warn.log.%d{yyyy-MM-dd}.log</FileNamePattern>
                
                <MaxHistory>10</MaxHistory>
                <totalSizeCap>8MB</totalSizeCap>
            </rollingPolicy>
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>${LOG_PATTERN}</pattern>
            </encoder>
        </appender>
    
        <appender name="fileDebugLog"  class="ch.qos.logback.core.rolling.RollingFileAppender">
            <filter class="ch.qos.logback.classic.filter.LevelFilter">
                <level>DEBUG</level>
                <onMatch>ACCEPT</onMatch>
                <onMismatch>DENY</onMismatch>
            </filter>
            <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
                
                <FileNamePattern>${LOG_HOME}/${APP_NAME}.debug.log.%d{yyyy-MM-dd}.log</FileNamePattern>
                
                <MaxHistory>10</MaxHistory>
                <totalSizeCap>1MB</totalSizeCap>
            </rollingPolicy>
            <encoder class="ch.qos.logback.classic.encoder.PatternLayoutEncoder">
                <pattern>${LOG_PATTERN}</pattern>
            </encoder>
        </appender>
    
        
        <root level="INFO">
            <appender-ref ref="consoleLog" />
            <appender-ref ref="fileErrorLog" />
            <appender-ref ref="fileInfoLog"/>
            <appender-ref ref="fileWarnLog" />
            <appender-ref ref="fileDebugLog" />
        </root>
    </configuration>

##### 3.写个controller 测试一下 #####

日志记录用的是 lombok 里面的小插件，也可以使用其他的。

@RestController
    @Slf4j
    public class LogController {
        @GetMapping("/search")
        public Object getInfo(
                @RequestParam(value = "keyword", required = false) String keyword) {
            String error = "这是error级别log";
            log.error("this is error log,{}", error);
    
            String warn = "这是warn级别log";
            log.warn("this is warn log,{}", warn);
    
            String info = "这是info级别log";
            log.info("this is info log,{}", info);
    
            Map<String, String> response = new HashMap<>();
            response.put("requestId", RequestIdUtil.getRequestId());  // 这块下面讲
            response.put("body", "body");
    
            return response;
    
        }
    }

在服务器上运行以后可以发现在当前目录下生成 log 文件夹，里面有4个级别的log文件，如下  
![日志级别文件][20200917145617463.png_pic_center]

##### 4.增加请求可追溯功能 #####

在步骤 2 和 3 里面都有一个关键词 requestId，它的作用是给每次请求加一个唯一标识，这样请求在系统流转就会带着这个唯一id打印日志，定位问题和分析很有用。

1.  主流方式是MDC，有兴趣的可以查一下，这里直接贴代码
2.  先写一个类用于操作MDC

import org.slf4j.MDC;
    import java.util.UUID;
    
    
    public class RequestIdUtil {
        public static final String REQUEST_ID = "requestId";
    
        public static void setRequestId() {
            MDC.put(REQUEST_ID, UUID.randomUUID().toString());
        }
    
    
        public static String getRequestId() {
            return MDC.get(REQUEST_ID);
        }
    
        public static void clear() {
            MDC.clear();
        }
    }

1.  再写一个过滤器，用于记录每次请求

import org.springframework.stereotype.Component;
    import javax.servlet.*;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    @Component
    public class RequestIdFilter implements Filter {
    
        private static final String REQUEST_ID_HEADER = "RequestId";
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            HttpServletResponse httpResponse = (HttpServletResponse) servletResponse;
            RequestIdUtil.setRequestId();
            String requestId = RequestIdUtil.getRequestId();
            httpResponse.setHeader(REQUEST_ID_HEADER, requestId);
            try {
                filterChain.doFilter(servletRequest, servletResponse);
            } finally {
                RequestIdUtil.clear();
            }
        }
    }

1.  测试

看一下步骤 3 的返回结果

{"requestId":"651a0b9b-1691-4fb2-a95f-e37275ee19e9","body":"body"}

查看一下日志内容：

2020-09-14 20:06:39.997 [http-nio-8088-exec-1] [651a0b9b-1691-4fb2-a95f-e37275ee19e9]  INFO  log.test.controller.LogController - this is info log,这是info级别log

[logback]: /images/1611075303713.png
[20200917145617463.png_pic_center]: /images/1611075267387.png