[Jaav SE/程序生命周期] 优雅的Java应用程序的启停钩子框架

序

• 了解 spring 生态及框架的 java er 都知道，spring 应用的生命周期管理及配套接口较为优雅、可扩展。

• 但脱离 spring 的 java 应用程序，如何优雅地启停、管理程序的生命周期呢？（以便应用程序在我们需要的运行阶段中进行相应的动作）

概述：Java普通应用程序的启停钩子框架

前置知识

java.lang.FunctionalInterface注解

• 推荐文献

• java.lang.FunctionalInterface : 函数式接口(JDK8+) - [Java SE/JDK] Java 注解机制 - 博客园/千千寰宇

Java普通应用程序的启停钩子框架

ApplicationStartupHook: 抽象的启动钩子接口

package org.example.app.hooks.startup;@FunctionalInterface
public interface ApplicationStartupHook {/*** execute the task* @throws Exception*/void execute() throws Exception;
}

ApplicationStartupHookManager : 统一管理启动钩子

package org.example.app.hooks.startup;import java.util.ArrayList;
import java.util.List;public class ApplicationStartupHookManager {private static final List<ApplicationStartupHook> hooks = new ArrayList<>();private static boolean executed = false;// 注册启动任务public static void registerHook(ApplicationStartupHook hook) {if (executed) {throw new IllegalStateException("Application startup hooks already executed");}hooks.add(hook);}// 执行所有启动任务public static void run() throws Exception {if (!executed) {for (ApplicationStartupHook hook : hooks) {hook.execute();}executed = true;}}
}

ApplicationShutdownHook : 关闭钩子

package org.example.app.hooks.shutdown;@FunctionalInterface
public interface ApplicationShutdownHook {/*** execute the task* @throws Exception*/void execute() throws Exception;
}

ApplicationShutdownHookManager : 统一管理关闭钩子

package org.example.app.hooks.shutdown;import lombok.Getter;
import org.example.app.hooks.startup.ApplicationStartupHook;import java.util.ArrayList;
import java.util.List;public class ApplicationShutdownHookManager {private static final List<ApplicationShutdownHook> hooks = new ArrayList<>();@Getterprivate static boolean executed = false;// 注册启动任务public static void registerHook(ApplicationShutdownHook hook) {if (executed) {throw new IllegalStateException("Application shutdown hooks already executed");}hooks.add(hook);}// 执行所有启动任务public static void run() throws Exception {if (!executed) {for (ApplicationShutdownHook hook : hooks) {hook.execute();}executed = true;}}
}

Demo应用 : Slf4j + Log4j2 + Log4j2 KafkaAppender + Kafka

Maven 依赖

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.example</groupId><artifactId>demos-application-parent</artifactId><version>1.0.0-SNAPSHOT</version><relativePath>../pom.xml</relativePath></parent><artifactId>log4j2-kafka-appender-demo-application</artifactId><packaging>jar</packaging><name>bdp-diagnosticbox-model</name><url>http://maven.apache.org</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><lombok.version>1.18.22</lombok.version><slf4j.version>1.7.30</slf4j.version><log4j.version>2.20.0</log4j.version><kafka-clients.version>2.7.2</kafka-clients.version></properties><dependencies><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>${lombok.version}</version></dependency><!-- log --><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-api</artifactId><version>${slf4j.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-api</artifactId><version>${log4j.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-core</artifactId><version>${log4j.version}</version></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-slf4j-impl</artifactId><version>${log4j.version}</version><exclusions><exclusion><artifactId>slf4j-api</artifactId><groupId>org.slf4j</groupId></exclusion></exclusions></dependency><dependency><groupId>org.apache.logging.log4j</groupId><artifactId>log4j-jul</artifactId><!--<version>2.13.3</version>--><version>${log4j.version}</version><scope>compile</scope></dependency><!-- log [end] --><!-- kafka client --><dependency><groupId>org.apache.kafka</groupId><artifactId>kafka-clients</artifactId><version>${kafka-clients.version}</version></dependency></dependencies>
</project>

配置文件

• resource/log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--<Configuration status="debug" name="demo-application" packages="org.example.app">-->
<Configuration status="off"><!-- 自定义属性 --><Properties><!-- 应用程序名称 --><Property name="application.name">bdp-xxx-app</Property><!-- 应用程序实例的主机地址 --><Property name="application.instance.host">${env:HOST_IP:-127.0.0.1}</Property><!-- 应用程序实例的名称，默认值: localInstance --><Property name="application.instance.name">${env:INSTANCE_NAME:-localInstance}</Property><!-- 字符集 --><Property name="log.encoding">UTF-8</Property><!-- 日志等级，默认 INFO --><Property name="log.level" value="${env:LOG_ACCESS:-INFO}" /><!--<Property name="log.access.level">${env:LOG_ACCESS:-INFO}</Property>--><!--<Property name="log.operation.level">${env:LOG_OPERATE:-INFO}</Property>--><Property name="log.threshold">${log.level}</Property><!-- org.apache.log4j.PatternLayout --><!--<Property name="log.layout" value="CustomPatternLayout"></Property>--><Property name="log.layout" value="PatternLayout"></Property><!-- property.log.layout.consolePattern=%d{yyyy/MM/dd HH:mm:ss.SSS} %-5p | %T | %t | (%C{1}.java:%L %M) | %m%n --><!-- [%d{yyyy/MM/dd HH:mm:ss.SSS}] [%traceId] [%-5p] [%t] [%C{1}.java:%L %M] %m%n --><!-- [%d{yyyy/MM/dd HH:mm:ss.SSS}] [%X{traceId}] [%-5p] [%t] [%C{1}.java:%L %M] %m%n --><!-- [%traceId] [${application.name}] [system] [%d{yyyy/MM/dd HH:mm:ss.SSS}] [%-5p] [%t] [%C{1}] %M:%L__|%X{traceId}|__%m%n --><!-- [${application.name}] [${instance.name}] [${env:HOST_IP}] [${env:CONTAINER_IP}] [%d{yyyy/MM/dd HH:mm:ss.SSS}] [%p] [%t] [%l] %m%n --><!-- ↓ sample: 2023-02-02 14:35:38,664 WARN  main (MonitorController.java:141 lambda$null$0) name: cn.seres.bd.dataservice.common.query, configLevel(Level):DEBUG, effectiveLevel: DEBUG --><!-- %d %-5p %t (%C{1}.java:%L %M) %m%n --><!-- [%d %r] [%-5p] [%t] [%l] [%m]%n --><!-- %d{yyyy-MM-dd HH\:mm\:ss} %-5p[%t] : %m%n --><!-- ↓ sample: 2025-02-21 15:24:27 INFO  | [2aa06a7b-a81f-469b-a0a0-679005bc35a3] | Log4jKafkaAppenderDemoEntry:36 - 这是一条信息日志 --><!--%d{HH:mm:ss.SSS} %-5p [%-7t] %F:%L - %m%n --><!--[%-4level] | %d{YYYY-MM-dd HH:mm:ss} | [%X{REQ_ID}] | %m| ${sys:java.home}%n--><!-- %d{yyyy-MM-dd HH:mm:ss} %-5p | [%X{REQ_ID}] | %c{1}:%L - %m%n --><!-- ${log.appender.kafka.producer.bootstrap.servers} | ${bundle:application:org.example.confgKey} | ${main:\\-logLevel} |  ${main:\\-\-log\.appender\.kafka\.producer\.bootstrap\.servers} | %c{1}:%L - %m%n --><Property name="log.layout.consolePattern">[%d{yyyy/MM/dd HH:mm:ss.SSS}] [%X{traceId}] [%-5p] [%t] [%C{1}.java:%L %M] %m%n</Property><Property name="log.layout.mainPattern" value="${log.layout.consolePattern}" /><!-- KafkaAppender 的属性值 --><!-- 方式1: 从环境变量获取 --><!--<Property name="log.appender.kafka.producer.bootstrap.servers" value="${env:KAFKA_PRODUCER_BOOTSTRAP_SERVERS:-127.0.0.1:9092}"/>--><!-- 方式2: 从 日志框架 MDC 中获取 --><!--<Property name="log.appender.kafka.producer.bootstrap.servers" value="%X{log.appender.kafka.producer.bootstrap.servers}"/>--><!-- 方式3: 从 应用程序的 main 方法启动入参中获取 --><Property name="log.appender.kafka.producer.bootstrap.servers" value="${main:\\-\-log\.appender\.kafka\.producer\.bootstrap\.servers}"/><!-- 目标 Appenders | 注: 属性值(如: ConsoleAppender)，对应的是 <Appender> 标签的 `name` 属性值 --><!-- 1. 标准输出/控制台的 Appender --><Property name="log.consoleAppender" value="MyConsoleAppender"/><!-- 2. 文件输出 系统类日志的 Appender --><Property name="log.systemFileAppender" value="MySystemFileAppender"/><!-- 3. 文件输出 访问类日志的 Appender --><!--<Property name="log.accessFileAppender">MyAccessFileAppender</Property>--><!-- 4. 文件输出 操作类日志的 Appender --><!--<Property name="log.operationFileAppender">MyOperationFileAppender</Property>--><!-- 5. 文件输出 协议类日志的 Appender --><!--<Property name="log.protocolFileAppender">MyProtocolFileAppender</Property>--><!-- 6. 远程 链路追踪系统的 Appender --><!--<Property name="log.linkTraceClientTargetAppender">MySkyWalkingClientAppender</Property>--><!-- 7. 远程 KAFKA/ELK 的 Appender --><Property name="log.loggingSystemMessageQueueAppender" value="MyKafkaAppender"/></Properties><!-- 输出器 --><Appenders><Console name="MyConsoleAppender" target="SYSTEM_OUT"><PatternLayout pattern="${log.layout.consolePattern}" /><!-- com.platform.sp.framework.log.layout.CustomPatternLayout --><!--<CustomPatternLayout pattern="${log.layout.consolePattern}" />--></Console><!--@warn1. 此 KafkaAppender 不建议在 生产环境 的 log4j2.xml/properties 中启用，因 无法从外部动态注入 kafka broker servers2. 针对第1点，需通过 自定义的 {@link org.example.app.hooks.startup.impl.Log4j2KafkaAppenderInitializer } ，实现程序启动时动态注册 KafkaAppender@Appender : KafkaAppender | org.apache.logging.log4j.core.appender.mom.kafka.KafkaAppender | log4j-core:2.20.0@note1. 计划在下一个主要版本中删除此附加程序！如果您正在使用此库，请使用官方支持渠道 与 Log4j 维护人员联系。from https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender2. 使用 Kafka Appender 需要额外的运行时依赖项 : org.apache.kafka:kafka-clients:{version}from https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender3. Kafka appender ignoreExceptions 必须设置为false，否则无法触发 FailOver Appender4. 确保不要让 `org.apache.kafka`Logger 日志记录的日志级别为 DEBUG，因为这将导致`KafkaAppender`递归日志记录from https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender@property//配置属性* name: Log Framework's Appender 's Name* topic : Kafka Topic Namekey:String : Kafka Message(`ProducerRecord`) 的 key。 支持 运行时属性替换，并在全局上下文 中进行评估。参考: https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender参考 : https://logging.apache.org/log4j/2.x/manual/lookups.html#global-context推荐值: key="$${web:contextName}" | contextName 是 log4j2 内置的变量ignoreExceptions:boolean[DefaultValue:true] : 如果false，日志记录异常将被转发给日志记录语句的调用者。否则，它们将被忽略。syncSend:boolean[DefaultValue:true] : 如果true，附加器将阻塞，直到 Kafka 服务器确认该记录为止。否则，附加器将立即返回，从而实现更低的延迟和更高的吞吐量。//嵌套属性FilterLayoutProperty[0..n] : 这些属性会直接转发给 Kafka 生产者。 有关更多详细信息，请参阅 Kafka 生产者属性。参考: https://kafka.apache.org/documentation.html#producerconfigsbootstrap.servers : 此属性是必需的key.serializer : 不应使用这些属性value.serializer : 不应使用这些属性--><Kafka name="MyKafkaAppender" topic="flink_monitor_log" key="$${web:contextName}" syncSend="true" ignoreExceptions="false"><!--<JsonTemplateLayout/>--><PatternLayout pattern="${log.layout.mainPattern}"/><Property name="bootstrap.servers" value="${log.appender.kafka.producer.bootstrap.servers}"/><Property name="max.block.ms">2000</Property></Kafka><RollingFile name="MyFailoverKafkaLogAppender" fileName="../log/failover/request.log"filePattern="../log/failover/request.%d{yyyy-MM-dd}.log"><ThresholdFilter level="INFO" onMatch="ACCEPT" onMismatch="DENY"/><PatternLayout><Pattern>${log.layout.mainPattern}</Pattern></PatternLayout><Policies><TimeBasedTriggeringPolicy /></Policies></RollingFile><!--<Failover name="Failover" primary="kafkaLog" retryIntervalSeconds="600"><Failovers><AppenderRef ref="MyFailoverKafkaLogAppender"/></Failovers></Failover>
--><!--异步输出 | org.apache.logging.log4j.core.async.AsyncLoggerConfig1. AsyncAppender接受对其他Appender的引用，并使LogEvents在单独的Thread上写入它们。2. 默认情况下，AsyncAppender使用 java.util.concurrent.ArrayBlockingQueue ，它不需要任何外部库。请注意，多线程应用程序在使用此appender时应小心：阻塞队列容易受到锁争用的影响，并且我们的 测试 表明，当更多线程同时记录时性能可能会变差。考虑使用无锁异步记录器以获得最佳性能。-->
<!--        <AsyncLogger name="kafkaAyncLogger" level="INFO" additivity="false"><appender-ref ref="Failover"/></AsyncLogger>--></Appenders><!-- 日志器--><Loggers><!-- 定义 RootLogger 等 全局性配置(不可随意修改) --><!-- rootLogger, 根记录器，所有记录器的父辈 | 指定根日志的级别 | All < Trace < Debug < Info < Warn < Error < Fatal < OFF --><Root level="${log.level}"> <!-- ${log.level} --><!-- 2.17.2 版本以下通过这种方式将 root 和 Appender关联起来 / 2.17.2 版本以上有更简便的写法 --><!-- rootLogger.appenderRef.stdout.ref=${log.consoleAppender} --><AppenderRef ref="${log.consoleAppender}" level="INFO" /><!-- rootLogger.appenderRef.kafka.ref=${log.loggingSystemMessageQueueAppender} -->
<!--            <AppenderRef ref="${log.loggingSystemMessageQueueAppender}"/> --><!-- MyKafkaAppender --></Root><!-- 指定个别 Class 的 Logger (可随意修改，建议在 nacos 上修改) --><!-- KafkaAppender | org.apache.logging.log4j.core.appender.mom.kafka.KafkaAppender1. 确保不要让 org.apache.kafka Logger 的日志级别为 DEBUG，因为这将导致递归日志记录2. 请记住将配置 additivity 属性设置为false--><Logger name="org.apache.kafka" level="WARN" additivity="false"><AppenderRef ref="${log.consoleAppender}"/></Logger></Loggers>
</Configuration>

Log4j2KafkaAppenderInitializer implements ApplicationStartupHook : 负责实现具体的启动钩子

package org.example.app.hooks.startup.impl;import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.appender.mom.kafka.KafkaAppender;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.example.app.constant.Constants;
import org.example.app.hooks.startup.ApplicationStartupHook;
import org.slf4j.MDC;import java.nio.charset.Charset;
import java.util.Collections;
import java.util.Map;
import java.util.Optional;
import java.util.Properties;/*** @description 基于 log4j2 日志框架，在程序启动时，根据程序的启动参数（kafka brokers地址）动态追加 KafkaAppender* @refrence-doc*  [1] Log4j2 配置日志记录发送到 kafka 中 - CSDN | https://blog.csdn.net/u010454030/article/details/132589450 【推荐】*  [2] 使用代码动态进行 Log4j2 的日志配置 - CSDN | https://blog.csdn.net/scruffybear/article/details/130230414 【推荐】*  [3] Apache Log4j2.x - Kafka Appender 【推荐】*      https://logging.apache.org/log4j/2.x/manual/appenders.html#KafkaAppender*      https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender*      {@link org.apache.logging.log4j.core.appender.mom.kafka.KafkaAppender }*  -----*  [4] Log4j2 - 动态生成Appender - 博客园 | https://www.cnblogs.com/yulinlewis/p/10217385.html*  [5] springboot动态添加log4j2的Appender - CSDN | https://blog.csdn.net/qq_25379811/article/details/127620062*  [6] log4j2.xml中动态读取配置 - CSDN | https://blog.csdn.net/xiaokanfuchen86/article/details/126695010 【推荐】*      https://logging.apache.org/log4j/2.x/manual/lookups.html#global-context 【推荐】* @gpt-promt*/
@Slf4j
public class Log4j2KafkaAppenderInitializer implements ApplicationStartupHook {@Getterprivate Properties applicationProperties;public Log4j2KafkaAppenderInitializer(Properties applicationProperties) {this.applicationProperties = applicationProperties;}@Overridepublic void execute() throws Exception {log.debug("Initializing {} ...", this.getClass().getCanonicalName());LoggerContext ctx = (LoggerContext) LogManager.getContext(false);Configuration config = ctx.getConfiguration();Appender kafkaAppender = createKafkaAppender(ctx, config, applicationProperties);kafkaAppender.start();//防止错误: Attempted to append to non-started appender testNameLevel level = getLevel(applicationProperties);config.getRootLogger().addAppender(kafkaAppender, level, null);// 添加 Appender 到配置中ctx.updateLoggers();log.debug("Initialized {} ...", this.getClass().getCanonicalName());}/*** @note*  1. required properties:*      1. {@link Constants.Log4j2KafkaAppender#LEVEL_PARAM}* @param applicationProperties* @return*/private static Level getLevel(Properties applicationProperties) {Level level = null;String levelStr = applicationProperties == null ? Constants.Log4j2KafkaAppender.LEVEL_DEFAULT : applicationProperties.getProperty( Constants.Log4j2KafkaAppender.LEVEL_PARAM );levelStr = (levelStr == null || levelStr.equals("") ) ? Constants.Log4j2KafkaAppender.LEVEL_DEFAULT : levelStr.toUpperCase();level = Level.getLevel(levelStr);log.info("user config's `{}`'s log level: {}", KafkaAppender.class.getCanonicalName(), levelStr);return level;}/*** create a kafka appender base on log4j2 framework* @reference-doc*  1. https://logging.apache.org/log4j/2.x/manual/appenders/message-queue.html#KafkaAppender* @note*  1. required properties:*      1. {@link Constants.Log4j2KafkaAppender#KAFKA_PRODUCER_TOPIC_PARAM}*      2. {@link ProducerConfig#BOOTSTRAP_SERVERS_CONFIG }*  2. optional properties:*      {@link ProducerConfig } 's Config Properties* @return*/private static Appender createKafkaAppender(LoggerContext loggerContext,Configuration configuration, Properties applicationProperties) {KafkaAppender kafkaAppender = null;if(loggerContext == null){loggerContext = (LoggerContext) LogManager.getContext(false);}if(configuration == null){configuration = loggerContext.getConfiguration();}final PatternLayout layout = PatternLayout.newBuilder().withCharset(Charset.forName("UTF-8")).withConfiguration(configuration).withPattern("%d %p %c{1.} [%t] %m%n").build();Filter filter = null;String topic = applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_TOPIC_PARAM);String appenderName = applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_TOPIC_PARAM) + "Log4J2KafkaAppender";Property [] propertyArray = propertiesToPropertyArray(applicationProperties);String messageKey = applicationProperties.getProperty( Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_KEY_PARAM );Boolean isIgnoreExceptions = Boolean.getBoolean(applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_APPENDER_IGNORE_EXCEPTIONS_PARAM, Constants.Log4j2KafkaAppender.KAFKA_APPENDER_IGNORE_EXCEPTIONS_DEFAULT));Boolean syncSend = Boolean.getBoolean(applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_SYNC_SEND_PARAM, Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_SYNC_SEND_DEFAULT));Boolean sendEventTimestamp = Boolean.getBoolean(applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_APPENDER_SEND_EVENT_TIMESTAMP_PARAM, Constants.Log4j2KafkaAppender.KAFKA_APPENDER_SEND_EVENT_TIMESTAMP_DEFAULT));//kafkaAppender = KafkaAppender.createAppender(layout, filter, appenderName, isIgnoreExceptions, topic, propertyArray, configuration, key );//此方式不支持传入 syncSend 参数//kafkaAppender = new KafkaAppender(name, layout, filter, isIgnoreExceptions, kafkaManager, getPropertyArray(), getRetryCount());//此方式，因构造器是 private，不支持kafkaAppender = KafkaAppender.newBuilder()//此方式 √.setName(appenderName).setConfiguration(configuration).setPropertyArray(propertyArray).setFilter(filter).setLayout(layout).setIgnoreExceptions(isIgnoreExceptions).setTopic(topic).setKey(messageKey).setSendEventTimestamp(sendEventTimestamp).setSyncSend(syncSend).setRetryCount(3).build();return kafkaAppender; // 需要替换为实际的 Appender 创建代码}/*** Java Properties 转 Log4j2 的 Property []* @return*/public static Property [] propertiesToPropertyArray(Properties properties){if(properties == null){return new Property[] {};}Property [] propertyArray = new Property[ properties.size() + 1];int i = 0;for(Map.Entry<Object, Object> entry : properties.entrySet() ) {Property property = Property.createProperty((String) entry.getKey(), (String) entry.getValue());propertyArray[i] = property;i++;}/*** 注入 org.apache.logging.log4j.core.appender.mom.kafka.KafkaAppender 所需的必填参数 {@link ProducerConfig.BOOTSTRAP_SERVERS_CONFIG}*/String kafkaBrokerServers = properties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM);if(kafkaBrokerServers != null && (!kafkaBrokerServers.trim().equals("")) ){propertyArray[i] = Property.createProperty( ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, kafkaBrokerServers);} else {throw new RuntimeException(String.format("The Property `%s` must be not empty for `%s`!", Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, KafkaAppender.class.getCanonicalName()));}return propertyArray;}
}

Slf4Initializer implements ApplicationStartupHook : 负责具体实现的启动钩子

package org.example.app.hooks.startup.impl;import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.example.app.constant.Constants;
import org.example.app.hooks.startup.ApplicationStartupHook;
import org.slf4j.MDC;import java.util.Optional;
import java.util.Properties;@Slf4j
public class Slf4Initializer implements ApplicationStartupHook {@Getterprivate Properties applicationProperties;public Slf4Initializer(Properties applicationProperties) {this.applicationProperties = applicationProperties;}@Overridepublic void execute() throws Exception {log.debug("Initializing {} ...", this.getClass().getCanonicalName());//设置 kafka 主机地址String kafkaProducerBootstrapServers = applicationProperties.getProperty(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM);kafkaProducerBootstrapServers = Optional.ofNullable(kafkaProducerBootstrapServers).<RuntimeException>orElseThrow(() -> {throw new RuntimeException(String.format("`{}` must be not empty!", Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM));});MDC.put(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, kafkaProducerBootstrapServers);log.info("MDC | {} : {}", Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, MDC.get(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM) );log.debug("Initialized {} ...", this.getClass().getCanonicalName());}
}

Slf4Finalizer implements ApplicationShutdownHook : 负责具体实现的钩子

package org.example.app.hooks.shutdown.impl;import lombok.Getter;
import lombok.extern.slf4j.Slf4j;
import org.example.app.constant.Constants;
import org.example.app.hooks.shutdown.ApplicationShutdownHook;
import org.slf4j.MDC;import java.util.Properties;@Slf4j
public class Slf4Finalizer implements ApplicationShutdownHook {@Getterprivate Properties applicationProperties;public Slf4Finalizer(Properties applicationProperties) {this.applicationProperties = applicationProperties;}@Overridepublic void execute() throws Exception {log.debug("Finalizing {} ...", Slf4Finalizer.class.getCanonicalName());// 清理MDClog.info("clear MDC before | {} : {}", Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, MDC.get(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM) );//MDC.clear();MDC.remove( Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM );//或仅清理需要的属性log.info("clear MDC after | {} : {}", Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, MDC.get(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM) );log.debug("Finalized {} ...", Slf4Finalizer.class.getCanonicalName());}
}

Log4jKafkaAppenderDemoEntry

package org.example.app;import org.apache.logging.log4j.core.layout.PatternLayout;
import org.example.app.constant.Constants;
import org.example.app.hooks.shutdown.ApplicationShutdownHookManager;
import org.example.app.hooks.shutdown.impl.Slf4Finalizer;
import org.example.app.hooks.startup.ApplicationStartupHookManager;
import org.example.app.hooks.startup.impl.Log4j2KafkaAppenderInitializer;
import org.example.app.hooks.startup.impl.Slf4Initializer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import java.util.Properties;public class Log4jKafkaAppenderDemoEntry {private static final Logger logger = LoggerFactory.getLogger(Log4jKafkaAppenderDemoEntry.class);private static final String APPLICATION_NAME = "Log4jKafkaAppenderDemoApplication";public static void main(String[] args) throws Exception {//从 nacos 等处动态获取配置 (此处可视为在模拟)Properties applicationProperties = new Properties();applicationProperties.put(Constants.Log4j2KafkaAppender.LEVEL_PARAM, "WARN");applicationProperties.put(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_BOOTSTRAP_SERVERS_PARAM, "127.0.0.1:9092");applicationProperties.put(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_TOPIC_PARAM, "flink_monitor_log");applicationProperties.put(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_KEY_PARAM, APPLICATION_NAME);applicationProperties.put(Constants.Log4j2KafkaAppender.KAFKA_PRODUCER_SYNC_SEND_PARAM, "true");applicationProperties.put(Constants.Log4j2KafkaAppender.KAFKA_APPENDER_IGNORE_EXCEPTIONS_PARAM, "false");enableLog4j2MainLookup(args);//可选步骤（非必须）runStartupHooks(applicationProperties);//运行启动钩子// 测试不同级别的日志logger.info("这是一条信息日志");logger.warn("这是一条警告日志");try {throw new RuntimeException("测试异常");} catch (Exception e) {logger.error("发生错误", e);}//关停钩子runShutdownHooks(applicationProperties);}public static void enableLog4j2MainLookup(String [] args){/*** 若 log4j2.[xml/properties/yaml] 中 Appender 的 pattern 欲以 `${main:\\-logLevel}` ，则需启用如下代码*/try {Class.forName("org.apache.logging.log4j.core.lookup.MainMapLookup").getDeclaredMethod("setMainArguments", String[].class).invoke(null, (Object) args);} catch (final ReflectiveOperationException e) {// Log4j Core is not used.}}public static void runStartupHooks(Properties applicationProperties) throws Exception {ApplicationStartupHookManager.registerHook( new Slf4Initializer(applicationProperties) );ApplicationStartupHookManager.registerHook( new Log4j2KafkaAppenderInitializer(applicationProperties) );ApplicationStartupHookManager.run();}public static void runShutdownHooks(Properties applicationProperties) throws Exception {ApplicationShutdownHookManager.registerHook( new Slf4Finalizer(applicationProperties) );ApplicationShutdownHookManager.run();}
}

X 参考文献

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