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);
}
@Override
protected 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);
@Autowired
private 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<jobHander, Cron> 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beanFactory
DefaultListableBeanFactory 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spring
Boolean 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>() {
@Override
public XxlJob inspect(Method method) {
return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);
}
});
} catch (Throwable ex) {
}
// 3.2 生成并注册方法的JobHander
for (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {
Method executeMethod = methodXxlJobEntry.getKey();
// 获取jobHander和Cron
XxlJobCron 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);
// regist
Method 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<jobHander, Cron> 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jobHandlerRepository
XxlJobExecutor 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beanName
String 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bean
continue;
}
// 1.2 过滤方法
Map<Method, XxlJob> annotatedMethods = null;
try {
annotatedMethods = MethodIntrospector.selectMethods(bean.getClass(),
new MethodIntrospector.MetadataLookup<XxlJob>() {
@Override
public 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.yaml</groupId>
<artifactId>snakeyaml</artifactId>
<version>1.29</version>
</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.yml
Yaml 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("${spring.cloud.nacos.config.namespace}")
private String namespace;
public ConfigService configService() throws NacosException {
Properties properties = new Properties();
properties.put("serverAddr", serverAddr);
properties.put("namespace", namespace);
return NacosFactory.createConfigService(properties);
}
}
package cn.jy.sjzl.util;
import cn.jy.sjzl.config.NacosConfig;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.nacos.api.config.ConfigService;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
/**
* nacos配置中，修改sjzl-loadjars.yml
*
* @author lijianyu
* @date 2023/04/19 17:59
**/
@Component
public class NacosConfigUtil {
private static Logger logger = LoggerFactory.getLogger(NacosConfigUtil.class);
@Autowired
private NacosConfig nacosConfig;
private String dataId = "sjzl-loadjars.yml";
@Value("${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.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.2.4</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<filters>
<filter>
<artifact>*:*</artifact>
<includes>
<include>com/jy/job/demo/**</include>
</includes>
</filter>
</filters>
<finalName>demoJob</finalName>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>