通过注解将接口代理到具体实现类调用

发布时间:2023年12月26日

背景

为了规范和限制业务方使用,我们使用接口加注解的方式来提供业务方来发布任务。业务方在调用该接口的时候,我们会将其动态代理到调用内部客户端真正的方法。

示例

Publisher内部接口(不希望业务方直接感知)

我们内部客户端有个Publisher接口,并有PublisherImpl实现了该接口,用来进行任务发布。但是我们不想业务在调用的时候去填写任务模版Template,而是希望其在接口上声明,我们通过注解扫描将其扫描进来并进行注册,然后帮助业务进行调用时动态加入模板信息。

package com.xxx.arch.mw.nbp.client.publish;

import com.xxx.arch.mw.nbp.common.domain.*;
import com.xxx.arch.mw.nbp.common.exception.BlockException;
import com.xxx.arch.mw.nbp.common.exception.NbpException;
import com.xxx.arch.mw.nbp.common.exception.RpcException;
import com.xxx.arch.mw.nbp.common.extension.Filter;
import com.xxx.arch.mw.nbp.share.dto.*;
import com.xxx.commons.data.domain.CursorPageQuery;
import com.xxx.commons.data.domain.DefaultCursorPage;
import com.xxx.commons.data.domain.DefaultPage;
import com.xxx.commons.data.domain.Result;

import java.util.List;
import java.util.Map;


public interface Publisher extends Bootable, Destroyable {

    /**
     * 注册某个任务发布者
     *
     * @param templateCode 任务模板
     */
    void register(final String templateCode) throws NbpException;

    /**
     * 反注册某个任务发布者
     *
     * @param templateCode 任务模板
     */
    void unregister(final String templateCode) throws NbpException;

    /**
     * 添加一个Filter
     *
     * @param filter
     */
    void addFilter(final Filter filter);

    /**
     * 移除一个Filter
     *
     * @param filter
     */
    void removeFilter(final Filter filter);

    /**
     * 发布一条调度任务
     *
     * @param singleDetail 发布数据包
     * @param template     发布模板
     * @return
     * @throws BlockException 流控降级异常
     * @throws NbpException   业务异常
     * @throws RpcException   超时异常
     */
    Result<SingleDetail> publish(SingleDetail singleDetail, Template template) throws NbpException;

    /**
     * 批量发布一批调度任务
     *
     * @param multiDetail 发布数据包
     * @param template    发布模板
     * @return
     * @throws BlockException 流控降级异常
     * @throws NbpException   业务异常
     * @throws RpcException   超时异常
     */
    Result<MultiResult<SingleDetail>> publish(MultiDetail multiDetail, Template template) throws NbpException;


}

PublishService接口(希望业务方感知)

为此,我们定义了一个PublishService,希望业务方通过继承该接口,然后业务方只需要声明一个接口继承PublishService接口即可。

package com.cainiao.arch.mw.nbp.client.publish;

import com.cainiao.arch.mw.nbp.common.domain.MultiDetail;
import com.cainiao.arch.mw.nbp.common.domain.SingleDetail;
import com.cainiao.arch.mw.nbp.common.exception.BlockException;
import com.cainiao.arch.mw.nbp.common.exception.NbpException;
import com.cainiao.arch.mw.nbp.common.exception.RpcException;
import com.cainiao.arch.mw.nbp.share.dto.MultiResult;
import com.cainiao.commons.data.domain.Result;

/**
 * @author cainiao-inc
 */
public interface PublishService {

    /**
     * 发布一条调度任务
     *
     * @param singleDetail 发布数据包
     * @return
     * @throws BlockException 流控降级异常
     * @throws NbpException   业务异常
     * @throws RpcException   超时异常
     */
    Result<SingleDetail> publish(SingleDetail singleDetail) throws NbpException;

    /**
     * 批量发布一批调度任务
     *
     * @param multiDetail 发布数据包
     * @return
     * @throws BlockException 流控降级异常
     * @throws NbpException   业务异常
     * @throws RpcException   超时异常
     */
    Result<MultiResult<SingleDetail>> publish(MultiDetail multiDetail) throws NbpException;
}

备注说明:

业务在调用PublishService的方法Result<SingleDetail> publish(SingleDetail singleDetail) throws NbpException;时代理到调用内部PublisherImpl的实际方法Result<SingleDetail> publish(SingleDetail singleDetail, Template template) throws NbpException;其中Template是我们在注解时将其扫描进来,在调用时动态带上。

业务接口声明

假设业务方声明了DemoPublisher接口,实际上在调用的时候,我们会将其代理到客户端内部的Publisher接口对应实现类

package com.xxx.arch.sample.spring;

import com.xxx.arch.mw.nbp.client.publish.PublishService;
import com.xxx.arch.mw.nbp.client.publish.annotation.DispatchPublisher;
import com.xxx.arch.mw.nbp.common.exception.NbpException;
import org.springframework.context.annotation.Description;

/**
 * @author cainiao-inc
 * @created 2022-08-15 10:16 AM
 * @description:
 */
@Description("NBP已升级到新内核")
@DispatchPublisher(code = "${demo.nbp.template.code}", desc = "NBP示例")
public interface DemoPublisher extends PublishService {

}

业务接口使用

业务方使用result = demoPublisher.publish(singleDetail); 来发布一个任务。

package com.xxx.arch;

import com.alibaba.fastjson.JSON;
import com.xxx.arch.mw.nbp.common.domain.SingleDetail;
import com.xxx.arch.mw.nbp.common.domain.Trigger;
import com.xxx.arch.mw.nbp.common.domain.Triggerable;
import com.xxx.arch.mw.nbp.common.exception.DegradeException;
import com.xxx.arch.mw.nbp.common.exception.FlowException;
import com.xxx.arch.mw.nbp.common.exception.NbpException;
import com.xxx.arch.mw.nbp.common.exception.RpcException;
import com.xxx.arch.sample.spring.DemoPublisher;
import com.xxx.arch.sample.spring.DemoObject;
import com.xxx.commons.data.domain.Result;
import com.xxx.commons.retry.backoff.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;

/**
 * @author chengxu
 */
@Controller
@RequestMapping("/v1/demo")
@DependsOn("demoPublisher")
public class DemoController {

    @Autowired
    private DemoPublisher demoPublisher;

    @GetMapping("/publish")
    public @ResponseBody
    Result<SingleDetail> publish() {
        Result<SingleDetail> result = null;
        try {
            // 构建业务对象
            DemoObject demoObject = buildDemoObject();
            // 构建默认单任务详情
            // SingleDetail singleDetail = new SingleDetail();
            // 构建带指定bizKey的但任务详情(仅后端是Defylab才支持,且需要先配置)
            // 构建不带Trigger的SingleDetail,对于ISS则是立即下发回调,对于Defylab按匹配的模板规则下发,未匹配到规则则立即下发回调
            SingleDetail singleDetail = new SingleDetail(demoObject.getName());
            // 添加用户自定义业务参数
            singleDetail.getUserContext().put("demoObject", JSON.toJSONString(demoObject));
            // 发布任务
            result = demoPublisher.publish(singleDetail);
        } catch (NbpException nbpException) {
            // 处理业务异常,调用NBP发布任务时被NBP判定为不合法的相关业务异常,需要业务方关注处理
        } catch (RpcException rpcException) {
            // 处理超时异常,调用NBP发布任务超时,业务方需自行尝试重试
        } catch (FlowException | DegradeException blockException) {
            // 处理流控异常,调用NBP发布任务被NBP限流规则限流,业务方需自行尝试重试
        }
        return result;
    }

    public DemoObject buildDemoObject() {
        DemoObject demoObject = new DemoObject();
        long id = ThreadLocalRandom.current().nextLong(1023);
        demoObject.setId(String.valueOf(id));
        demoObject.setName(String.join("_", "demo", String.valueOf(id)));
        demoObject.setSeq(1);
        return demoObject;
    }
}

代理实现

上述示例可以让业务不感知我们的任务模版,限制其一个接口只能发布对应任务模板的任务,避免发送到其它任务模板。那么我们来看下内部是如何实现的。

思路

显然接口是无法直接使用的,最终得有个中间代理类。然后在初始化时我们需要通过注解扫描的方式将对应注解扫描到,并注入到Spring容器中,这样在业务方使用时就可以通过@Autowired注解将其声明的注解注入到对应的位置。而在接口调用时,通过方法代理到实际的Publisher的对应方法上面去。

实现

PublisherProxy
package com.xxx.arch.mw.nbp.client.spring;

import org.springframework.cglib.proxy.InvocationHandler;

import java.lang.reflect.Method;

/**
 * @author cainiao-inc
 */
public interface PublisherProxy extends InvocationHandler {

    @Override
    Object invoke(Object proxy, Method method, Object[] args) throws Throwable;

}
PublisherProxyImpl
package com.xxx.arch.mw.nbp.client.spring;

import com.xxx.arch.mw.nbp.client.publish.Publisher;
import com.xxx.arch.mw.nbp.client.publish.annotation.DispatchPublisher;
import com.xxx.arch.mw.nbp.client.publish.annotation.DispatchTemplate;
import com.xxx.arch.mw.nbp.common.domain.MultiDetail;
import com.xxx.arch.mw.nbp.common.domain.NbpCode;
import com.xxx.arch.mw.nbp.common.domain.SingleDetail;
import com.xxx.arch.mw.nbp.common.domain.Template;
import com.xxx.arch.mw.nbp.common.exception.NbpException;

import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Set;


public class PublisherProxyImpl implements PublisherProxy {

    private final Publisher publisher;
    private final Class<?> clazz;
    private final Template clazzTemplate;

    public PublisherProxyImpl(Publisher publisher) {
        this(publisher, null);
    }

    public PublisherProxyImpl(Publisher publisher, Class<?> clazz) {
        this.publisher = publisher;
        this.clazz = clazz;

        if (this.clazz != null) {
            DispatchPublisher clazzTemplateAnnotation = clazz.getAnnotation(DispatchPublisher.class);
            if (clazzTemplateAnnotation != null && !clazzTemplateAnnotation.code().isEmpty()) {
                clazzTemplate = new Template(clazzTemplateAnnotation.code(), clazzTemplateAnnotation.desc());
            } else {
                clazzTemplate = null;
            }
        } else {
            clazzTemplate = null;
        }

    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (RESERVED_METHOD.contains(method)) {
            return method.invoke(this, args);
        }

        DispatchTemplate methodTemplateAnnotation = method.getAnnotation(DispatchTemplate.class);
        Template template = methodTemplateAnnotation == null ? clazzTemplate :
                new Template(methodTemplateAnnotation.code(), methodTemplateAnnotation.desc());
        if (template == null) {
            throw new NbpException(NbpCode.ILLEGAL_PARAM.getCode(),
                    method.getName() + "'s DispatchTemplate annotation and "
                            + "DispatchPublisher annotation can't be all empty or invalid!");
        }
        Class<?>[] methodParameterTypes = method.getParameterTypes();
        if (methodParameterTypes.length > 0) {
            Class<?> methodParameterType = methodParameterTypes[0];
            if (methodParameterType == SingleDetail.class) {
                return this.publisher.publish((SingleDetail) args[0], template);
            } else if (methodParameterType == MultiDetail.class) {
                return this.publisher.publish((MultiDetail) args[0], template);
            } else {
                throw new NbpException(NbpCode.UNSUPPORTED.getCode(),
                        "Unsupported parameter type, parameter type must be SingleDetail or MultiWrapper");
            }
        }
        throw new NbpException(NbpCode.UNSUPPORTED.getCode(), "Unsupported parameter type");
    }

    private final static Set<Method> RESERVED_METHOD = new HashSet<>();

    static {
        for (Method method : Object.class.getMethods()) {
            RESERVED_METHOD.add(method);
        }

    }

}

为了规范化,我们也使用BeanDefinition方式来初始化

PublisherProxyBeanDefinitionBuilder
package com.xxx.arch.mw.nbp.client.spring;

import com.xxx.arch.mw.nbp.client.constant.ClientConstants;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.context.ApplicationContext;

import java.util.ArrayList;
import java.util.List;

/**
 * @created 2022-11-30 3:08 PM
 * @description:
 */
public class PublisherProxyBeanDefinitionBuilder {
    private Class<?> clazz;
    private ApplicationContext context;

    private List<String> dependsOns = new ArrayList<>();

    PublisherProxyBeanDefinitionBuilder() {
    }

    PublisherProxyBeanDefinitionBuilder clazz(Class<?> clazz) {
        this.clazz = clazz;
        return this;
    }

    PublisherProxyBeanDefinitionBuilder context(ApplicationContext context) {
        this.context = context;
        return this;
    }

    PublisherProxyBeanDefinitionBuilder dependsOns(List<String> dependsOns) {
        if (dependsOns != null) {
            this.dependsOns = dependsOns;
        }
        return this;
    }

    PublisherProxyBeanDefinitionBuilder dependsOn(String dependsOn) {
        if (dependsOn == null) {
            return this;
        }
        if (this.dependsOns != null) {
            this.dependsOns = new ArrayList<>();
        }
        this.dependsOns.add(dependsOn);
        return this;
    }


    BeanDefinition build() {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(PublisherProxyFactoryBean.class);
        builder.addPropertyValue("clazz", this.clazz);
        builder.addPropertyReference("publisher", ClientConstants.NBP_PUBLISHER_IMPL_BEAN_NAME);
        builder.addDependsOn(ClientConstants.NBP_PUBLISHER_IMPL_BEAN_NAME);
        for (String dependsOn : dependsOns) {
            builder.addDependsOn(dependsOn);
        }

        return builder.getBeanDefinition();
    }

}
PublisherProxyFactoryBean
package com.xxx.arch.mw.nbp.client.spring;

import com.xxx.arch.mw.nbp.client.publish.Publisher;
import com.xxx.arch.mw.nbp.common.domain.NbpCode;
import com.xxx.arch.mw.nbp.common.exception.NbpException;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.EnvironmentAware;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Proxy;

/**
 * @created 2022-11-30 3:32 PM
 * @description:
 */
public class PublisherProxyFactoryBean implements FactoryBean<Object>, EnvironmentAware, InitializingBean {
    private ConfigurableEnvironment environment;
    private Publisher publisher;
    private Class<?> clazz;

    public PublisherProxyFactoryBean() {
    }

    @Override
    public Object getObject() throws Exception {
        Constructor<? extends PublisherProxyImpl> constructor = PublisherProxyImpl.class
                .getDeclaredConstructor(Publisher.class, Class.class);
        final PublisherProxyImpl instance = constructor.newInstance(publisher, clazz);

        Object object = Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{clazz}, (proxy, method, args) -> {
            try {
                return instance.invoke(proxy, method, args);
            } catch (NbpException e) {
                throw e;
            } catch (Throwable throwable) {
                if (throwable instanceof InvocationTargetException) {
                    throw ((InvocationTargetException) throwable).getTargetException();
                } else {
                    throw new NbpException(NbpCode.CLIENT_ERROR.getCode(), throwable.getMessage(), throwable);
                }
            }
        });

        return object;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
    }

    @Override
    public Class<?> getObjectType() {
        return clazz;
    }

    @Override
    public void setEnvironment(Environment environment) {
        this.environment = (ConfigurableEnvironment) environment;
    }

    @Override
    public boolean isSingleton() {
        return true;
    }

    public Publisher getPublisher() {
        return publisher;
    }

    public void setPublisher(Publisher publisher) {
        this.publisher = publisher;
    }

    public Class<?> getClazz() {
        return clazz;
    }

    public void setClazz(Class<?> clazz) {
        this.clazz = clazz;
    }
}

注入到Spring上下文

期间省略了注解扫描的实现(该实现后续文章补上)

   private void resolveRegistryPublisherProxyBeanDefinition(BeanDefinitionRegistry registry, Set<Class> classSet) {
        for (Class clazz : classSet) {
            String beanName = this.scanHelper.getComponentName(clazz);
            String[] dependOns = (clazz.getAnnotation(DependsOn.class) == null) ? new String[0] :
                    ((DependsOn) clazz.getAnnotation(DependsOn.class)).value();
            PublisherProxyBeanDefinitionBuilder beanDefinitionBuilder = new PublisherProxyBeanDefinitionBuilder();
            beanDefinitionBuilder.context(context);
            beanDefinitionBuilder.clazz(clazz);
            beanDefinitionBuilder.dependsOns(Arrays.asList(dependOns));
            BeanDefinition beanDefinition = beanDefinitionBuilder.build();
            if (context.containsBean(beanName)) {
                throw new IllegalArgumentException("[NBP-CLIENT-STARTER] Spring context already has a bean named " + beanName
                        + ", please change @DispatchPublisher field name.");
            }
            // 移除,避免被其它框架注解扫描
            try {
                LOGGER.debug("NBP-CLIENT-STARTER", "remove interface beanDefinition of {} in spring context.", beanName);
                registry.removeBeanDefinition(beanName);
            } catch (Exception e) {
                LOGGER.debug("NBP-CLIENT-STARTER", "remove interface beanDefinition of {} in spring context error with reason:",
                        beanName, e.getMessage());
            }

            // 重新注册
            registry.registerBeanDefinition(beanName, beanDefinition);
            LOGGER.info("NBP-CLIENT-STARTER", "registered beanDefinition of {} in spring context.", beanName);
        }
    }

文章来源:https://blog.csdn.net/shallowgrave/article/details/135223004
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