SpringBoot日志打印实践

背景

在项目当中，我们经常需要打印一些日志埋点信息，这些日志埋点信息，在后续软件的运维、稳定性建设中发挥了巨大的作用：

问题追踪：通过埋点日志中的关键信息，帮助定位系统异常原因
系统监控：通过日志，监控系统的运行情况，包括性能指标、访问频率、错误等
数据分析：分析用户行为、系统性能和业务趋势等
调试：通过查看日志，帮助开发人员了解程序在执行过程中的状态和行为

SpringBoot整合Logback实现日志打印

SpringBoot默认使用Slf4j作为日志门面，并集成Logback作为日志实现。要在springboot中实现日志打印，只需要引入下列依赖：

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-logging</artifactId>
</dependency>

然后在配置文件中，配置对应的日志级别：

logging:level:root: INFO

对某些特定的包，需要指定日志级别，则配置如下：

logging:level:com.example.demo: DEBUG

最后，我们创建logback-spring.xml，来自定义日志的配置信息，包括日志输出文件、日志格式等

<?xml version="1.0" encoding="UTF-8"?>
<configuration><property name="LOG_PATH" value="logs"/><property name="LOG_FILE" value="${LOG_PATH}/spring-boot-logger.log"/><appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender"><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"><file>common.log</file><rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"><fileNamePattern>${LOG_PATH}/spring-boot-logger.%d{yyyy-MM-dd}.log</fileNamePattern><maxHistory>30</maxHistory></rollingPolicy><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><root level="INFO"><appender-ref ref="CONSOLE"/><appender-ref ref="FILE"/></root>
</configuration>

然后，我们在需要打印日志的类，加上Slf4j注解，然后使用log来打印日志信息即可，如下代码所示：

package com.yang.web.controller;import com.yang.api.common.ResultT;
import com.yang.api.common.command.RegisterCommand;
import com.yang.api.common.dto.UserDTO;
import com.yang.api.common.facade.UserFacade;
import com.yang.web.request.RegisterRequest;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping(value = "/user")
@Slf4j
public class UserController {@Autowiredprivate UserFacade userFacade;@GetMapping(value = "/{id}")public ResultT<UserDTO> queryById(@PathVariable("id") Integer id) {log.info("queryById===========");return userFacade.getById(id);}@PostMapping(value = "/register")public ResultT<String> register(@RequestBody RegisterRequest registerRequest) {RegisterCommand registerCommand = convert2RegisterCommand(registerRequest);return userFacade.register2(registerCommand);}private RegisterCommand convert2RegisterCommand(RegisterRequest registerRequest) {RegisterCommand registerCommand = new RegisterCommand();registerCommand.setLoginId(registerRequest.getLoginId());registerCommand.setEmail(registerRequest.getEmail());registerCommand.setPassword(registerRequest.getPassword());registerCommand.setExtendMaps(registerRequest.getExtendMaps());return registerCommand;}
}

然后访问queryById，打印结果如下：

日志打印工具类

在logback-spring.xml中，我们虽然能配置日志打印的格式，但是不够灵活，因此，我们可以添加一个日志打印工具类，通过该工具类，来自定义项目中的日志打印格式，以方便后续更好地通过日志排查、定位问题。

首先创建一个日志打印抽象类，定义日志打印的格式：

package com.yang.core.infrastructure.log;import org.apache.commons.lang3.StringUtils;
import org.springframework.util.CollectionUtils;import java.util.ArrayList;
import java.util.List;public abstract class AbstractLogPrinter {protected String bizCode;protected List<String> params = new ArrayList<>();protected String msg;protected Throwable e;public AbstractLogPrinter addBizCode(String bizCode) {this.bizCode = bizCode;return this;}public AbstractLogPrinter addMsg(String msg) {this.msg = msg;return this;}public AbstractLogPrinter addParam(String key, String value) {this.params.add(key);this.params.add(value);return this;}public AbstractLogPrinter addThrowable(Throwable e) {this.e = e;return this;}public abstract void printBizLog();public abstract void printErrorLog();public abstract String getSeparator();public String commonContent() {StringBuilder stringBuilder = new StringBuilder();String separator = getSeparator();stringBuilder.append("bizCode").append(":").append(this.bizCode).append(separator);if (!CollectionUtils.isEmpty(params)) {for (int i = 0; i < params.size(); i += 2) {stringBuilder.append(params.get(i)).append(":").append(params.get(i + 1)).append(separator);}}if (StringUtils.isNotEmpty(msg)) {stringBuilder.append("msg").append(":").append(msg).append(separator);}return stringBuilder.toString();}
}

然后创建日志打印实现类，在实现类中，定制实现日志打印的级别、分隔符等内容

package com.yang.core.infrastructure.log;import lombok.extern.slf4j.Slf4j;@Slf4j
public class PlatformLogPrinter extends AbstractLogPrinter {public void printBizLog() {log.info(commonContent());}public void printErrorLog() {if (e != null) {log.error(commonContent(), e);} else {log.error(commonContent());}}@Overridepublic String getSeparator() {return "<|>";}
}

同时，为了方便打印日志，创建一个日志打印创建者

package com.yang.core.infrastructure.log;public class PlatformLogger {public static AbstractLogPrinter build() {return new PlatformLogPrinter();}
}

上述内容准备完毕后，我们在controller中，使用PlatformLogger来打印日志，修改后的代码如下：

package com.yang.web.controller;import com.yang.api.common.ResultT;
import com.yang.api.common.command.RegisterCommand;
import com.yang.api.common.dto.UserDTO;
import com.yang.api.common.facade.UserFacade;
import com.yang.core.infrastructure.log.PlatformLogger;
import com.yang.web.request.RegisterRequest;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;@RestController
@RequestMapping(value = "/user")
public class UserController {@Autowiredprivate UserFacade userFacade;@GetMapping(value = "/{id}")public ResultT<UserDTO> queryById(@PathVariable("id") Integer id) {PlatformLogger.build().addBizCode("queryById").addParam("id", id.toString()).addMsg("query by id").printBizLog();return userFacade.getById(id);}@GetMapping(value = "/error/{id}")public ResultT testError(@PathVariable("id") Integer id) {try {int i = 1 / 0;} catch (Throwable t) {PlatformLogger.build().addBizCode("testError").addParam("id", id.toString()).addMsg("test error print").addThrowable(t).printErrorLog();}return ResultT.fail();}@PostMapping(value = "/register")public ResultT<String> register(@RequestBody RegisterRequest registerRequest) {RegisterCommand registerCommand = convert2RegisterCommand(registerRequest);return userFacade.register2(registerCommand);}private RegisterCommand convert2RegisterCommand(RegisterRequest registerRequest) {RegisterCommand registerCommand = new RegisterCommand();registerCommand.setLoginId(registerRequest.getLoginId());registerCommand.setEmail(registerRequest.getEmail());registerCommand.setPassword(registerRequest.getPassword());registerCommand.setExtendMaps(registerRequest.getExtendMaps());return registerCommand;}
}

启动项目，分别访问queryById和testError，打印日志内容如下：

日志分文件打印

一般情况下，我们的项目会分为不同的模块，每一个模块承担不同的职责，比如bussiness模块，主要是负责业务逻辑代码的实现，业务逻辑编排等；web模块主要负责http请求的接收，参数的校验，入参转化为业务层入参等；而core模块主要负责基础能力实现，比如持久化数据库、领域服务实现等。

对于不同的模块，我们希望将日志输出到不同的文件当中，从而协助我们后续定位问题以及建设不同模块下的监控，包括基础服务监控、业务成功率监控等。

因此，我们在不同的模块下，分别实现不同的日志打印工具类：

package com.yang.web.log;import com.yang.core.infrastructure.log.AbstractLogPrinter;public class WebLogger {public static AbstractLogPrinter build() {return new WebLogPrinter();}
}package com.yang.web.log;import com.yang.core.infrastructure.log.AbstractLogPrinter;
import lombok.extern.slf4j.Slf4j;@Slf4j
public class WebLogPrinter extends AbstractLogPrinter {@Overridepublic void printBizLog() {log.info(commonContent());}@Overridepublic void printErrorLog() {if (this.e != null) {log.error(commonContent(), e);} else {log.error(commonContent());}}@Overridepublic String getSeparator() {return "<|>";}
}package com.yang.business.log;public class BusinessLogger {public static BusinessLogPrinter build() {return new BusinessLogPrinter();}
}package com.yang.business.log;import com.yang.core.infrastructure.log.AbstractLogPrinter;
import lombok.extern.slf4j.Slf4j;@Slf4j
public class BusinessLogPrinter extends AbstractLogPrinter {@Overridepublic void printBizLog() {log.info(commonContent());}@Overridepublic void printErrorLog() {if (this.e != null) {log.error(commonContent(), e);} else {log.error(commonContent());}}@Overridepublic String getSeparator() {return "<|>";}
}

然后我们修改logback-spring.xml文件，将不同的日志打印工具类，输出到不同的日志文件中

<?xml version="1.0" encoding="UTF-8"?>
<configuration><property name="LOG_PATH" value="logs"/><property name="LOG_FILE" value="${LOG_PATH}/spring-boot-logger.log"/><appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender"><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"><file>common.log</file><rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"><fileNamePattern>${LOG_PATH}/spring-boot-logger.%d{yyyy-MM-dd}.log</fileNamePattern><maxHistory>30</maxHistory></rollingPolicy><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><appender name="PLATFORM_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"><file>platform.log</file><rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"><fileNamePattern>${LOG_PATH}/platform-logger.%d{yyyy-MM-dd}.log</fileNamePattern><maxHistory>30</maxHistory></rollingPolicy><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><appender name="BUSINESS_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"><file>business.log</file><rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"><fileNamePattern>${LOG_PATH}/business-logger.%d{yyyy-MM-dd}.log</fileNamePattern><maxHistory>30</maxHistory></rollingPolicy><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><appender name="WEB_FILE" class="ch.qos.logback.core.rolling.RollingFileAppender"><file>web.log</file><rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy"><fileNamePattern>${LOG_PATH}/web-logger.%d{yyyy-MM-dd}.log</fileNamePattern><maxHistory>30</maxHistory></rollingPolicy><encoder><pattern>%d{yyyy-MM-dd HH:mm:ss} - %msg%n</pattern></encoder></appender><root level="INFO"><appender-ref ref="CONSOLE"/><appender-ref ref="FILE"/></root><!-- 工具类PlatformLogPrinter的logger --><logger name="com.yang.core.infrastructure.log.PlatformLogPrinter" level="INFO" additivity="false"><appender-ref ref="PLATFORM_FILE" /></logger><!-- 工具类BusinessLogPrinter的logger --><logger name="com.yang.business.log.BusinessLogPrinter" level="INFO" additivity="false"><appender-ref ref="BUSINESS_FILE" /></logger><!-- 工具类WebLogPrinter的logger --><logger name="com.yang.web.log.WebLogPrinter" level="INFO" additivity="false"><appender-ref ref="WEB_FILE" /></logger>
</configuration>

最后，分别在web模块、business模块和core模块下，添加埋点日志

// WEB模块
@GetMapping(value = "/{id}")public ResultT<UserDTO> queryById(@PathVariable("id") Integer id) {WebLogger.build().addBizCode("userController_queryById").addParam("id", id.toString()).addMsg("query by id").printBizLog();return userFacade.getById(id);}// Business模块
@Overridepublic ResultT<UserDTO> getById(Integer id) {UserQueryDomainRequest userQueryDomainRequest = new UserQueryDomainRequest.UserQueryDomainRequestBuilder().queryMessage(id.toString()).userQueryType(UserQueryType.ID).build();UserQueryDomainResponse userQueryDomainResponse = userDomainService.query(userQueryDomainRequest);List<UserAccount> userAccountList = userQueryDomainResponse.getUserAccountList();UserDTO userDTO = null;if (!CollectionUtils.isEmpty(userAccountList)) {UserAccount userAccount = userAccountList.get(0);userDTO = userDTOConvertor.convert2DTO(userAccount);}BusinessLogger.build().addBizCode("userFacade_getById").addParam("id", id.toString()).addParam("userDTO", JSONObject.toJSONString(userDTO)).addMsg("get by id").printBizLog();return ResultT.success(userDTO);}// core模块
public UserQueryDomainResponse query(UserQueryDomainRequest userQueryDomainRequest) {UserQueryType userQueryType = userQueryDomainRequest.getUserQueryType();UserDO userDO = null;switch (userQueryType) {case ID:userDO = queryById(Integer.valueOf(userQueryDomainRequest.getQueryMessage()));break;case EMAIL:userDO = queryByEmail(userQueryDomainRequest.getQueryMessage());break;case LOGIN_ID:userDO = queryByLoginId(userQueryDomainRequest.getQueryMessage());break;}if (userDO == null) {return new UserQueryDomainResponse();}UserAccount userAccount = new UserAccount();userAccount.setId(userDO.getId());userAccount.setLoginId(userDO.getLoginId());userAccount.setEmail(userDO.getEmail());userAccount.setFeatureMap(FeatureUtils.convert2FeatureMap(userDO.getFeatures()));userAccount.setCreateTime(userDO.getCreateTime());userAccount.setUpdateTime(userDO.getUpdateTime());UserQueryDomainResponse userQueryDomainResponse = new UserQueryDomainResponse();List<UserAccount> userAccounts = new ArrayList<>();userAccounts.add(userAccount);userQueryDomainResponse.setUserAccountList(userAccounts);PlatformLogger.build().addBizCode("userDomainService_query").addParam("queryMsg", userQueryDomainRequest.getQueryMessage()).addParam("queryType", userQueryDomainRequest.getUserQueryType().name()).printBizLog();return userQueryDomainResponse;}