Classloader隔離技術在業務監控中的應用詳解

@Service
public class DubboDemoScript implements DemoScript {
    @Resource
    private DemoService demoService;
    @Override
    public boolean filter(JSONObject jsonObject) {
        // 這裡省略數據過濾邏輯 由業務使用方實現
        return true;
    }
    @Override
    public String check(JSONObject jsonObject) {
        Long id = jsonObject.getLong("id");
        // 數據校驗，由業務使用方實現
        Response responseResult = demoService.queryById(id);
        log.info("[DubboClassloaderTestDemo]返回結果={}", JsonUtils.serialize(responseResult));
        return JsonUtils.serialize(responseResult);
    }
}

public class CustomClassLoader extends URLClassLoader {
/**
 * @param jarPath jar文件目錄地址
 * @return
 */
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();
    }
    /**
     * 重寫loadClass方法，按照類包路徑規則拉進行加載Class到jvm
     * @param name 類全限定名
     * @return
     * @throws ClassNotFoundException
     */
    @Override
    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
        // 這裡定義類加載規則，和findClass方法一起組合打破雙親
        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;
    }
}

/**
 * 
 * @param serverName 服務名 （@FeignClient主鍵中的name值）
 *  eg：@FeignClient("demo-interfaces") 
 * @param beanName feign對象名稱 eg: DemoFeignClient
 * @param targetClass feign的Class對象 
 * @param <T> FeignClient主鍵標記的Object
 * @return
 */
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) {
        // 當前應用配置
    ApplicationConfig application = new ApplicationConfig();
    application.setName("demo-service");
    // 連接註冊中心配置
    RegistryConfig registry = new RegistryConfig();
    registry.setAddress(registryAddress);
    // ReferenceConfig為重對象，內部封裝瞭與註冊中心的連接，以及與服務提供方的連接
    ReferenceConfig reference = new ReferenceConfig<>(); // 此實例很重，封裝瞭與註冊中心的連接以及與提供者的連接，請自行緩存，否則可能造成內存和連接泄漏
    reference.setApplication(application);
    reference.setRegistry(registry); // 多個註冊中心可以用setRegistries()
    reference.setInterface(clazz);
    reference.setVersion("1.0");
    // 註意：此代理對象內部封裝瞭所有通訊細節，這裡用dubbo2.4版本以後提供的緩存類ReferenceConfigCache
    ReferenceConfigCache cache = ReferenceConfigCache.getCache();
    Object dubboBean = cache.get(reference);    
    dubboBeanMap.put(beanName, dubboBean);
    // 註冊bean
    SpringContextUtils.registerBean(beanName, dubboBean);
    // 註入bean
    SpringContextUtils.autowireBean(dubboBean);
}