Java-springboot动态加载jar包，动态配置
一、概述
1、背景
目前数据治理服务中有众多治理任务，当其中任一治理任务有改动需要升级或新增一个治理任务时，都需要将数据治理服务重启，会影响其他治理任务的正常运行。
2、目标
- 能够动态启动、停止任一治理任务
- 能够动态升级、添加治理任务
- 启动、停止治理任务或升级、添加治理任务不能影响其他任务
3、方案
- 为了支持业务代码尽量的解耦，把部分业务功能通过动态加载的方式加载到主程序中，以满足可插拔式的加载、组合式的部署。
- 配合xxl-job任务调度框架，将数据治理任务做成xxl-job任务的方式注册到xxl-job中，方便统一管理。
二、动态加载
1、自定义类加载器
URLClassLoader 是一种特殊的类加载器，可以从指定的 URL 中加载类和资源。它的主要作用是动态加载外部的 JAR 包或者类文件，从而实现动态扩展应用程序的功。为了便于管理动态加载的jar包，自定义类加载器继承URLClassloader。
package cn.jy.sjzl.util;import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;/*** 自定义类加载器** @author lijianyu* @date 2023/04/03 17:54**/
public class MyClassLoader extends URLClassLoader {private Map<String, Class<?>> loadedClasses = new ConcurrentHashMap<>();public Map<String, Class<?>> getLoadedClasses() {return loadedClasses;}public MyClassLoader(URL[] urls, ClassLoader parent) {super(urls, parent);}@Overrideprotected Class<?> findClass(String name) throws ClassNotFoundException {// 从已加载的类集合中获取指定名称的类Class<?> clazz = loadedClasses.get(name);if (clazz != null) {return clazz;}try {// 调用父类的findClass方法加载指定名称的类clazz = super.findClass(name);// 将加载的类添加到已加载的类集合中loadedClasses.put(name, clazz);return clazz;} catch (ClassNotFoundException e) {e.printStackTrace();return null;}}public void unload() {try {for (Map.Entry<String, Class<?>> entry : loadedClasses.entrySet()) {// 从已加载的类集合中移除该类String className = entry.getKey();loadedClasses.remove(className);try{// 调用该类的destory方法，回收资源Class<?> clazz = entry.getValue();Method destory = clazz.getDeclaredMethod("destory");destory.invoke(clazz);} catch (Exception e ) {// 表明该类没有destory方法}}// 从其父类加载器的加载器层次结构中移除该类加载器close();} catch (Exception e) {e.printStackTrace();}}
}- 自定义类加载器中，为了方便类的卸载，定义一个map保存已加载的类信息。key为这个类的ClassName，value为这个类的类信息。
- 同时定义了类加载器的卸载方法，卸载方法中，将已加载的类的集合中移除该类。由于此类可能使用系统资源或调用线程，为了避免资源未回收引起的内存溢出，通过反射调用这个类中的destroy方法，回收资源。
- 最后调用close方法。
2、动态加载
由于此项目使用spring框架，以及xxl-job任务的机制调用动态加载的代码，因此要完成以下内容
- 将动态加载的jar包读到内存中
- 将有spring注解的类，通过注解扫描的方式，扫描并手动添加到spring容器中。
- 将@XxlJob注解的方法，通过注解扫描的方式，手动添加到xxljob执行器中。
package com.jy.dynamicLoad;import com.jy.annotation.XxlJobCron;
import com.jy.classLoader.MyClassLoader;
import com.xxl.job.core.executor.impl.XxlJobSpringExecutor;
import com.xxl.job.core.handler.annotation.XxlJob;
import com.xxl.job.core.handler.impl.MethodJobHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.core.MethodIntrospector;
import org.springframework.core.annotation.AnnotatedElementUtils;
import org.springframework.stereotype.Component;import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.Enumeration;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;/*** @author lijianyu* @date 2023/04/29 13:18**/
@Component
public class DynamicLoad {private static Logger logger = LoggerFactory.getLogger(DynamicLoad.class);@Autowiredprivate ApplicationContext applicationContext;private Map<String, MyClassLoader> myClassLoaderCenter = new ConcurrentHashMap<>();@Value("${dynamicLoad.path}")private String path;/*** 动态加载指定路径下指定jar包* @param path* @param fileName* @param isRegistXxlJob 是否需要注册xxljob执行器，项目首次启动不需要注册执行器* @return map 创建xxljob任务时需要的参数配置*/ public void loadJar(String path, String fileName, Boolean isRegistXxlJob) throws ClassNotFoundException, InstantiationException, IllegalAccessException {File file = new File(path +"/" + fileName);Map<String, String> jobPar = new HashMap<>();// 获取beanFactoryDefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) applicationContext.getAutowireCapableBeanFactory();// 获取当前项目的执行器try {// URLClassloader加载jar包规范必须这么写URL url = new URL("jar:file:" + file.getAbsolutePath() + "!/");URLConnection urlConnection = url.openConnection();JarURLConnection jarURLConnection = (JarURLConnection)urlConnection;// 获取jar文件JarFile jarFile = jarURLConnection.getJarFile();Enumeration<JarEntry> entries = jarFile.entries();// 创建自定义类加载器，并加到map中方便管理MyClassLoader myClassloader = new MyClassLoader(new URL[] { url }, ClassLoader.getSystemClassLoader());myClassLoaderCenter.put(fileName, myClassloader);Set<Class> initBeanClass = new HashSet<>(jarFile.size());// 遍历文件while (entries.hasMoreElements()) {JarEntry jarEntry = entries.nextElement();if (jarEntry.getName().endsWith(".class")) {// 1. 加载类到jvm中// 获取类的全路径名String className = jarEntry.getName().replace('/', '.').substring(0, jarEntry.getName().length() - 6);// 1.1进行反射获取myClassloader.loadClass(className);}}Map<String, Class<?>> loadedClasses = myClassloader.getLoadedClasses();XxlJobSpringExecutor xxlJobExecutor = new XxlJobSpringExecutor();for(Map.Entry<String, Class<?>> entry : loadedClasses.entrySet()){String className = entry.getKey();Class<?> clazz = entry.getValue();// 2. 将有@spring注解的类交给spring管理// 2.1 判断是否注入springBoolean flag = SpringAnnotationUtils.hasSpringAnnotation(clazz);if(flag){// 2.2交给spring管理BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(clazz);AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();// 此处beanName使用全路径名是为了防止beanName重复String packageName = className.substring(0, className.lastIndexOf(".") + 1);String beanName = className.substring(className.lastIndexOf(".") + 1);beanName = packageName + beanName.substring(0, 1).toLowerCase() + beanName.substring(1);// 2.3注册到spring的beanFactory中beanFactory.registerBeanDefinition(beanName, beanDefinition);// 2.4允许注入和反向注入beanFactory.autowireBean(clazz);beanFactory.initializeBean(clazz, beanName);/*if(Arrays.stream(clazz.getInterfaces()).collect(Collectors.toSet()).contains(InitializingBean.class)){initBeanClass.add(clazz);}*/initBeanClass.add(clazz);}// 3. 带有XxlJob注解的方法注册任务// 3.1 过滤方法Map<Method, XxlJob> annotatedMethods = null;try {annotatedMethods = MethodIntrospector.selectMethods(clazz,new MethodIntrospector.MetadataLookup<XxlJob>() {@Overridepublic XxlJob inspect(Method method) {return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);}});} catch (Throwable ex) {}// 3.2 生成并注册方法的JobHanderfor (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {Method executeMethod = methodXxlJobEntry.getKey();// 获取jobHander和CronXxlJobCron xxlJobCron = executeMethod.getAnnotation(XxlJobCron.class);if(xxlJobCron == null){throw new CustomException("500", executeMethod.getName() + "()，没有添加@XxlJobCron注解配置定时策略");}if (!CronExpression.isValidExpression(xxlJobCron.value())) {throw new CustomException("500", executeMethod.getName() + "(),@XxlJobCron参数内容错误");}XxlJob xxlJob = methodXxlJobEntry.getValue();jobPar.put(xxlJob.value(), xxlJobCron.value());if (isRegistXxlJob) {executeMethod.setAccessible(true);// registMethod initMethod = null;Method destroyMethod = null;xxlJobExecutor.registJobHandler(xxlJob.value(), new CustomerMethodJobHandler(clazz, executeMethod, initMethod, destroyMethod));}}}// spring bean实际注册initBeanClass.forEach(beanFactory::getBean);} catch (IOException e) {logger.error("读取{} 文件异常", fileName);e.printStackTrace();throw new RuntimeException("读取jar文件异常: " + fileName);}}
}以下是判断该类是否有spring注解的工具类
apublic class SpringAnnotationUtils {private static Logger logger = LoggerFactory.getLogger(SpringAnnotationUtils.class);/*** 判断一个类是否有 Spring 核心注解** @param clazz 要检查的类* @return true 如果该类上添加了相应的 Spring 注解；否则返回 false*/public static boolean hasSpringAnnotation(Class<?> clazz) {if (clazz == null) {return false;}//是否是接口if (clazz.isInterface()) {return false;}//是否是抽象类if (Modifier.isAbstract(clazz.getModifiers())) {return false;}try {if (clazz.getAnnotation(Component.class) != null ||clazz.getAnnotation(Repository.class) != null ||clazz.getAnnotation(Service.class) != null ||clazz.getAnnotation(Controller.class) != null ||clazz.getAnnotation(Configuration.class) != null) {return true;}}catch (Exception e){logger.error("出现异常：{}",e.getMessage());}return false;}
}
注册xxljob执行器的操作是仿照的xxljob中的XxlJobSpringExecutor的注册方法。
3、动态卸载
动态卸载的过程，就是将动态加载的代码，从内存，spring以及xxljob中移除。
代码如下：
/*** 动态卸载指定路径下指定jar包* @param fileName* @return map 创建xxljob任务时需要的参数配置*/ public void unloadJar(String fileName) throws IllegalAccessException, NoSuchFieldException {// 获取加载当前jar的类加载器MyClassLoader myClassLoader = myClassLoaderCenter.get(fileName);// 获取jobHandlerRepository私有属性,为了卸载xxljob任务Field privateField = XxlJobExecutor.class.getDeclaredField("jobHandlerRepository");// 设置私有属性可访问privateField.setAccessible(true);// 获取私有属性的值jobHandlerRepositoryXxlJobExecutor xxlJobSpringExecutor = new XxlJobSpringExecutor();Map<String, IJobHandler> jobHandlerRepository = (ConcurrentHashMap<String, IJobHandler>) privateField.get(xxlJobSpringExecutor);// 获取beanFactory，准备从spring中卸载DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory) applicationContext.getAutowireCapableBeanFactory();Map<String, Class<?>> loadedClasses = myClassLoader.getLoadedClasses();Set<String> beanNames = new HashSet<>();for (Map.Entry<String, Class<?>> entry: loadedClasses.entrySet()) {// 1. 将xxljob任务从xxljob执行器中移除// 1.1 截取beanNameString key = entry.getKey();String packageName = key.substring(0, key.lastIndexOf(".") + 1);String beanName = key.substring(key.lastIndexOf(".") + 1);beanName = packageName + beanName.substring(0, 1).toLowerCase() + beanName.substring(1);// 获取bean，如果获取失败，表名这个类没有加到spring容器中，则跳出本次循环Object bean = null;try{bean = applicationContext.getBean(beanName);}catch (Exception e){// 异常说明spring中没有这个beancontinue;}// 1.2 过滤方法Map<Method, XxlJob> annotatedMethods = null;try {annotatedMethods = MethodIntrospector.selectMethods(bean.getClass(),new MethodIntrospector.MetadataLookup<XxlJob>() {@Overridepublic XxlJob inspect(Method method) {return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);}});} catch (Throwable ex) {}// 1.3 将job从执行器中移除for (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {XxlJob xxlJob = methodXxlJobEntry.getValue();jobHandlerRepository.remove(xxlJob.value());}// 2.0从spring中移除，这里的移除是仅仅移除的bean，并未移除bean定义beanNames.add(beanName);beanFactory.destroyBean(beanName, bean);}// 移除bean定义Field mergedBeanDefinitions = beanFactory.getClass().getSuperclass().getSuperclass().getDeclaredField("mergedBeanDefinitions");mergedBeanDefinitions.setAccessible(true);Map<String, RootBeanDefinition> rootBeanDefinitionMap = ((Map<String, RootBeanDefinition>) mergedBeanDefinitions.get(beanFactory));for (String beanName : beanNames) {beanFactory.removeBeanDefinition(beanName);// 父类bean定义去除rootBeanDefinitionMap.remove(beanName);}// 卸载父任务，子任务已经在循环中卸载jobHandlerRepository.remove(fileName);// 3.2 从类加载中移除try {// 从类加载器底层的classes中移除连接Field field = ClassLoader.class.getDeclaredField("classes");field.setAccessible(true);Vector<Class<?>> classes = (Vector<Class<?>>) field.get(myClassLoader);classes.removeAllElements();// 移除类加载器的引用myClassLoaderCenter.remove(fileName);// 卸载类加载器myClassLoader.unload();} catch (NoSuchFieldException e) {logger.error("动态卸载的类，从类加载器中卸载失败");e.printStackTrace();} catch (IllegalAccessException e) {logger.error("动态卸载的类，从类加载器中卸载失败");e.printStackTrace();}logger.error("{} 动态卸载成功", fileName);}
4、动态配置
使用动态加载时，为了避免服务重新启动后丢失已加载的任务包，使用动态配置的方式，加载后动态更新初始化加载配置。
以下提供了两种自己实际操作过的配置方式。
4.1 动态修改本地yml
动态修改本地yml配置文件，需要添加snakeyaml的依赖
4.1.1 依赖引入
<dependency><groupId>org.yamlgroupId><artifactId>snakeyamlartifactId><version>1.29version>
dependency>
4.1.2 工具类
读取指定路径下的配置文件，并进行修改。
package com.jy.util;import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;
import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.Yaml;import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;/*** 用于动态修改bootstrap.yml配置文件* @author lijianyu* @date 2023/04/18 17:57**/
@Component
public class ConfigUpdater {public void updateLoadJars(List<String> jarNames) throws IOException {// 读取bootstrap.ymlYaml yaml = new Yaml();InputStream inputStream = new FileInputStream(new File("src/main/resources/bootstrap.yml"));Map<String, Object> obj = yaml.load(inputStream);inputStream.close();obj.put("loadjars", jarNames);// 修改FileWriter writer = new FileWriter(new File("src/main/resources/bootstrap.yml"));DumperOptions options = new DumperOptions();options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);options.setPrettyFlow(true);Yaml yamlWriter = new Yaml(options);yamlWriter.dump(obj, writer);}
}
4.2 动态修改nacos配置
Spring Cloud Alibaba Nacos组件完全支持在运行时通过代码动态修改配置，还提供了一些API供开发者在代码里面实现动态修改配置。在每次动态加载或卸载数据治理任务jar包时，执行成功后都会进行动态更新nacos配置。
package cn.jy.sjzl.config;import com.alibaba.nacos.api.NacosFactory;
import com.alibaba.nacos.api.config.ConfigService;
import com.alibaba.nacos.api.exception.NacosException;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;import java.util.Properties;@Configuration
public class NacosConfig {@Value("${spring.cloud.nacos.server-addr}")private String serverAddr;@Value("${spring.cloud.nacos.config.namespace}")private String namespace;public ConfigService configService() throws NacosException {Properties properties = new Properties();properties.put("serverAddr", serverAddr);properties.put("namespace", namespace);return NacosFactory.createConfigService(properties);}
}
package cn.jy.sjzl.util;import cn.jy.sjzl.config.NacosConfig;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.nacos.api.config.ConfigService;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;/*** nacos配置中，修改sjzl-loadjars.yml** @author lijianyu* @date 2023/04/19 17:59**/
@Component
public class NacosConfigUtil {private static Logger logger = LoggerFactory.getLogger(NacosConfigUtil.class);@Autowiredprivate NacosConfig nacosConfig;private String dataId = "sjzl-loadjars.yml";@Value("${spring.cloud.nacos.config.group}")private String group;/*** 从nacos配置文件中，添加初始化jar包配置* @param jarName 要移除的jar包名* @throws Exception*/public void addJarName(String jarName) throws Exception {ConfigService configService = nacosConfig.configService();String content = configService.getConfig(dataId, group, 5000);// 修改配置文件内容YAMLMapper yamlMapper = new YAMLMapper();ObjectMapper jsonMapper = new ObjectMapper();Object yamlObject = yamlMapper.readValue(content, Object.class);String jsonString = jsonMapper.writeValueAsString(yamlObject);JSONObject jsonObject = JSONObject.parseObject(jsonString);List<String> loadjars;if (jsonObject.containsKey("loadjars")) {loadjars = (List<String>) jsonObject.get("loadjars");}else{loadjars = new ArrayList<>();}if (!loadjars.contains(jarName)) {loadjars.add(jarName);}jsonObject.put("loadjars" , loadjars);Object yaml = yamlMapper.readValue(jsonMapper.writeValueAsString(jsonObject), Object.class);String newYamlString = yamlMapper.writeValueAsString(yaml);boolean b = configService.publishConfig(dataId, group, newYamlString);if(b){logger.info("nacos配置更新成功");}else{logger.info("nacos配置更新失败");}}
}
三、分离打包
分离打包时，根据实际情况在pom.xml中修改以下配置
<build><plugins><plugin><groupId>org.apache.maven.pluginsgroupId><artifactId>maven-shade-pluginartifactId><version>3.2.4version><executions><execution><phase>packagephase><goals><goal>shadegoal>goals><configuration><filters><filter><artifact>*:*artifact><includes><include>com/jy/job/demo/**include>includes>filter>filters><finalName>demoJobfinalName>configuration>execution>executions>plugin>plugins>
build>
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