Classloader隔离技术在业务监控中的应用详解

@Service
public class DubboDemoScript implements DemoScript {
    @Resource
    private DemoService demoService;
    @Override
    public boolean filter(JSONObject jsonObject) {
        // 这里省略数据过滤逻辑 由业务使用方实现
        return true;
    }
    @Override
    public String check(JSONObject jsonObject) {
        Long id = jsonObject.getLong("id");
        // 数据校验，由业务使用方实现
        Response responseResult = demoService.queryById(id);
        log.info("[DubboClassloaderTestDemo]返回结果={}", JsonUtils.serialize(responseResult));
        return JsonUtils.serialize(responseResult);
    }
}

public class CustomClassLoader extends URLClassLoader {

private CustomClassLoader createCustomClassloader(String jarPath) throws MalformedURLException {
    File file = new File(jarPath);
    URL url = file.toURI().toURL();
    List<URL> urlList = Lists.newArrayList(url);
    URL[] urls = new URL[urlList.size()];
    urls = urlList.toArray(urls);
    return new CustomJarClassLoader(urls, classLoader.getParent());
}
public CustomClassLoader(URL[] urls, ClassLoader parent) {
    super(urls, parent);
}

public class CustomClassLoader extends URLClassLoader {
    public JarFile jarFile;
    public ClassLoader parent;
    public CustomClassLoader(URL[] urls, JarFile jarFile, ClassLoader parent) {
        super(urls, parent);
        this.jarFile = jarFile;
        this.parent = parent;
    }
    public CustomClassLoader(URL[] urls, ClassLoader parent) {
        super(urls, parent);
    }
    private static String classNameToJarEntry(String name) {
        String classPath = name.replaceAll("\\.", "\\/");
        return new StringBuilder(classPath).append(".class").toString();
    }
    
    @Override
    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        // 这里定义类加载规则，和findClass方法一起组合打破双亲
        if (name.startsWith("com.xx") || name.startsWith("com.yyy")) {
           return this.findClass(name);
        }
        return super.loadClass(name, resolve);
    }
    @Override
    protected Class<?> findClass(String name) throws ClassNotFoundException {
        Class clazz = null;
        try {
            String jarEntryName = classNameToJarEntry(name);
            if (jarFile == null) {
                return clazz;
            }
            JarEntry jarEntry = jarFile.getJarEntry(jarEntryName);
            if (jarEntry != null) {
                InputStream inputStream = jarFile.getInputStream(jarEntry);
                byte[] bytes = IOUtils.toByteArray(inputStream);
                clazz = defineClass(name, bytes, 0, bytes.length);
            }
        } catch (IOException e) {
            log.info("Custom classloader load calss {} failed", name)
        }
        return clazz;
    }
}

public static <T> T build(String serverName, String beanName, Class<T> targetClass) {
    return buildClient(serverName, beanName, targetClass);
}
private static <T> T buildClient(String serverName, String beanName, Class<T> targetClass) {
    T t = (T) BEAN_CACHE.get(serverName + "-" + beanName);
    if (Objects.isNull(t)) {
        FeignClientBuilder.Builder<T> builder = new FeignClientBuilder(applicationContext).forType(targetClass, serverName);
        t = builder.build();
        BEAN_CACHE.put(serverName + "-" + beanName, t);
    }
    return t;
}

public void registerDubboBean(Class clazz, String beanName) {
        // 当前应用配置
    ApplicationConfig application = new ApplicationConfig();
    application.setName("demo-service");
    // 连接注册中心配置
    RegistryConfig registry = new RegistryConfig();
    registry.setAddress(registryAddress);
    // ReferenceConfig为重对象，内部封装了与注册中心的连接，以及与服务提供方的连接
    ReferenceConfig reference = new ReferenceConfig<>(); // 此实例很重，封装了与注册中心的连接以及与提供者的连接，请自行缓存，否则可能造成内存和连接泄漏
    reference.setApplication(application);
    reference.setRegistry(registry); // 多个注册中心可以用setRegistries()
    reference.setInterface(clazz);
    reference.setVersion("1.0");
    // 注意：此代理对象内部封装了所有通讯细节，这里用dubbo2.4版本以后提供的缓存类ReferenceConfigCache
    ReferenceConfigCache cache = ReferenceConfigCache.getCache();
    Object dubboBean = cache.get(reference);    
    dubboBeanMap.put(beanName, dubboBean);
    // 注册bean
    SpringContextUtils.registerBean(beanName, dubboBean);
    // 注入bean
    SpringContextUtils.autowireBean(dubboBean);
}