COLA的扩展性使用和源码研究

cola扩展点使用和设计初探

封装变化，可灵活应对程序的需求变化。

扩展点使用

步骤:

定义扩展点接口，类型可以是校验器，转换器，实体； 必须以ExtPt结尾，表示一个扩展点。

比如，我定义一个云枢的组织结构的扩展点接口，消息发送扩展点，二开扩展点，webapi的rest接口扩展点点。

定义扩展点接口

package com.authine.web.cola.domain.customer;

import com.alibaba.cola.extension.ExtensionPointI;
import com.authine.web.cola.dto.domainmodel.Department;

import java.util.List;

/**
 * @author carter
 * create_date  2020/5/25 14:25
 * description     定义扩展点接口，对组织机构的某些方法。
 */

public interface OrganizationExtPt extends ExtensionPointI {

    /**
     * 根据corpId查询企业下所有部门
     *
     * @param corpId        企业编号
     * @param includeDelete 是否包含删除的部门
     * @return 部门
     */
    List<Department> getDepartmentsByCorpId(String corpId, Boolean includeDelete);

}

比如业务扩展分为钉钉，微信：

这里基于扩展理论（x,y）;

即通过 业务，用例，场景得到扩展点的key, 那后扩展类就是针对实际的业务场景的业务处理代码；

钉钉场景扩展点实现

package com.authine.web.cola.domain.customer.extpt;

import com.alibaba.cola.extension.Extension;
import com.authine.web.cola.dto.domainmodel.Department;
import com.authine.web.cola.domain.customer.OrganizationExtPt;
import lombok.extern.slf4j.Slf4j;

import java.util.Collections;
import java.util.List;

/**
 * @author carter
 * create_date  2020/5/25 14:32
 * description     企业部门在通过corpId获取部门列表的场景下，钉钉的扩展
 */
@Extension(bizId = "organize",useCase = "getByCorpId",scenario = "dingTalk")
@Slf4j
public class DingTalkOrganizationExt implements OrganizationExtPt {

    @Override
    public List<Department> getDepartmentsByCorpId(String corpId, Boolean includeDelete) {

        log.info("在组织结构业务，通过企业编号获取部门列表的用例，在钉钉的场景下业务的实现处理方式");

        log.info("通过钉钉的配置信息和API获取得到组织信息，并组装成云枢识别的部门信息");

        Department department = new Department();

        department.setName("dingTalk");
        department.setCorpId(corpId);

        return Collections.singletonList(department);
    }
}

企业微信扩展点实现

package com.authine.web.cola.domain.customer.extpt;

import com.alibaba.cola.extension.Extension;
import com.authine.web.cola.dto.domainmodel.Department;
import com.authine.web.cola.domain.customer.OrganizationExtPt;
import lombok.extern.slf4j.Slf4j;

import java.util.Collections;
import java.util.List;

/**
 * @author carter
 * create_date  2020/5/25 15:05
 * description     企业微信的扩展点实现
 */
@Extension(bizId = "organize",useCase = "getByCorpId",scenario = "wechat")
@Slf4j
public class WechatOrganizationExt  implements OrganizationExtPt {
    @Override
    public List<Department> getDepartmentsByCorpId(String corpId, Boolean includeDelete) {

        log.info("业务：组织机构，用例：通过企业编号获取部门 , 场景：企业微信");

        log.info("通过企业微信的API获取组织的部门信息，然后包装为需要的部门列表");

        Department department = new Department();

        department.setName("wechat");
        department.setCorpId(corpId);

        return Collections.singletonList(department);
    }
}

扩展点使用

在命令执行器中使用。

package com.authine.web.cola.executor.query;

import com.alibaba.cola.command.Command;
import com.alibaba.cola.command.CommandExecutorI;
import com.alibaba.cola.dto.MultiResponse;
import com.alibaba.cola.extension.ExtensionExecutor;
import com.authine.web.cola.dto.domainmodel.Department;
import com.authine.web.cola.domain.customer.OrganizationExtPt;
import com.authine.web.cola.dto.OrgnizationQry;

import java.util.List;

/**
 * @author carter
 * create_date  2020/5/25 15:09
 * description     查询组织机构的指令执行
 */
@Command
public class OrgazationQueryExe implements CommandExecutorI<MultiResponse, OrgnizationQry> {

    private final ExtensionExecutor extensionExecutor;

    public OrgazationQueryExe(ExtensionExecutor extensionExecutor) {
        this.extensionExecutor = extensionExecutor;
    }

    @Override
    public MultiResponse execute(OrgnizationQry cmd) {

        String corpId = cmd.getCorpId();

        boolean includeDelete = cmd.isIncludeDelete();

        List<Department> departmentList = extensionExecutor.execute(OrganizationExtPt.class, cmd.getBizScenario(),
                ex -> ex.getDepartmentsByCorpId(corpId, includeDelete));

        return MultiResponse.ofWithoutTotal(departmentList);
    }
}

测试扩展点的使用

封装一个http接口来调用。

package com.authine.web.cola.controller;

import com.alibaba.cola.dto.MultiResponse;
import com.alibaba.cola.extension.BizScenario;
import com.authine.web.cola.api.OrganizationServiceI;
import com.authine.web.cola.dto.OrgnizationQry;
import com.authine.web.cola.dto.domainmodel.Department;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class OrganizationController {

    private final OrganizationServiceI organizationServiceI;

    public OrganizationController(OrganizationServiceI organizationServiceI) {
        this.organizationServiceI = organizationServiceI;
    }

    @GetMapping(value = "/organization/getDepartmentsByCorpId/{corpId}/{scenario}")
    public MultiResponse<Department> listCustomerByName(@PathVariable("corpId") String corpId,@PathVariable("scenario") String scenario){

        OrgnizationQry qry = new OrgnizationQry();
        qry.setCorpId(corpId);
        qry.setIncludeDelete(true);
        qry.setBizScenario(BizScenario.valueOf("organize","getByCorpId",scenario));

        return organizationServiceI.getDepartmentsByCorpId(qry);
    }

}

下面是使用接口进行测试的结果。

小结

基于元数据的扩展点设计，可以灵活的应对 业务场景的多样性，以及灵活的支持版本升级。

其它的扩展点（校验器，转换器）其它等，也可以轻松做到扩展。

使用例子在框架的单元测试用例中。

扩展点设计

设计本质

设计理念。是一种基于数据的配置扩展。即基于注解上带上配置数据。

@Extension 源码如下：

package com.alibaba.cola.extension;

import com.alibaba.cola.common.ColaConstant;
import org.springframework.stereotype.Component;

import java.lang.annotation.*;

@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@Component
public @interface Extension {
    String bizId()  default BizScenario.DEFAULT_BIZ_ID;
    String useCase() default BizScenario.DEFAULT_USE_CASE;
    String scenario() default BizScenario.DEFAULT_SCENARIO;
}

图文说明如下：

下面深入源码进行研究。从使用的源码出发。

ExtensionExecutor

类图如下。

首先，标注了Component,所以，在ioc中可以通过类型拿到实例。

最后，执行函数是放在父类AbstractComponentExecutor中；

重点分析一下它实现的功能：即通过坐标得到扩展实例；

 /**
     * if the bizScenarioUniqueIdentity is "ali.tmall.supermarket"
     *
     * the search path is as below:
     * 1、first try to get extension by "ali.tmall.supermarket", if get, return it.
     * 2、loop try to get extension by "ali.tmall", if get, return it.
     * 3、loop try to get extension by "ali", if get, return it.
     * 4、if not found, try the default extension
     * @param targetClz
     */
    protected <Ext> Ext locateExtension(Class<Ext> targetClz, BizScenario bizScenario) {
        checkNull(bizScenario);

        Ext extension;
        String bizScenarioUniqueIdentity = bizScenario.getUniqueIdentity();
        logger.debug("BizScenario in locateExtension is : " + bizScenarioUniqueIdentity);

        // first try
        extension = firstTry(targetClz, bizScenarioUniqueIdentity);
        if (extension != null) {
            return extension;
        }

        // loop try
        extension = loopTry(targetClz, bizScenarioUniqueIdentity);
        if (extension != null) {
            return extension;
        }

        throw new ColaException("Can not find extension with ExtensionPoint: "+targetClz+" BizScenario:"+bizScenarioUniqueIdentity);
    }

实现步骤如下：

ExtensionRepository

package com.alibaba.cola.extension;

import java.util.HashMap;
import java.util.Map;

import org.springframework.stereotype.Component;

import lombok.Getter;

/**
 * ExtensionRepository
 * @author fulan.zjf 2017-11-05
 */
@Component
public class ExtensionRepository {

    @Getter
    private Map<ExtensionCoordinate, ExtensionPointI> extensionRepo = new HashMap<>();

}

里面是一个空的map,主要还是看组装过程。看下面的ExtensionRegister;

ExtensionRegister

看名字，就是注册扩展的组件。

/*
 * Copyright 2017 Alibaba.com All right reserved. This software is the
 * confidential and proprietary information of Alibaba.com ("Confidential
 * Information"). You shall not disclose such Confidential Information and shall
 * use it only in accordance with the terms of the license agreement you entered
 * into with Alibaba.com.
 */
package com.alibaba.cola.boot;

import com.alibaba.cola.common.ApplicationContextHelper;
import com.alibaba.cola.common.ColaConstant;
import com.alibaba.cola.exception.framework.ColaException;
import com.alibaba.cola.extension.*;
import org.apache.commons.lang3.ArrayUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * ExtensionRegister
 * @author fulan.zjf 2017-11-05
 */
@Component
public class ExtensionRegister implements RegisterI{

    @Autowired
    private ExtensionRepository extensionRepository;

    @Override
    public void doRegistration(Class<?> targetClz) {
        ExtensionPointI extension = (ExtensionPointI) ApplicationContextHelper.getBean(targetClz);
        Extension extensionAnn = targetClz.getDeclaredAnnotation(Extension.class);
        String extPtClassName = calculateExtensionPoint(targetClz);
        BizScenario bizScenario = BizScenario.valueOf(extensionAnn.bizId(), extensionAnn.useCase(), extensionAnn.scenario());
        ExtensionCoordinate extensionCoordinate = new ExtensionCoordinate(extPtClassName, bizScenario.getUniqueIdentity());
        ExtensionPointI preVal = extensionRepository.getExtensionRepo().put(extensionCoordinate, extension);
        if (preVal != null) {
            throw new ColaException("Duplicate registration is not allowed for :" + extensionCoordinate);
        }
    }

    /**
     * @param targetClz
     * @return
     */
    private String calculateExtensionPoint(Class<?> targetClz) {
        Class[] interfaces = targetClz.getInterfaces();
        if (ArrayUtils.isEmpty(interfaces))
            throw new ColaException("Please assign a extension point interface for "+targetClz);
        for (Class intf : interfaces) {
            String extensionPoint = intf.getSimpleName();
            if (StringUtils.contains(extensionPoint, ColaConstant.EXTENSION_EXTPT_NAMING))
                return intf.getName();
        }
        throw new ColaException("Your name of ExtensionPoint for "+targetClz+" is not valid, must be end of "+ ColaConstant.EXTENSION_EXTPT_NAMING);
    }

}

注册过程如下：

以上是扩展类注册到扩展仓库的过程。

注册时机。启动的时刻通过包扫描进行注册。

RegisterFactory

把各种注册器放入到ioc中，通过一个统一的方法返回。

/*
 * Copyright 2017 Alibaba.com All right reserved. This software is the
 * confidential and proprietary information of Alibaba.com ("Confidential
 * Information"). You shall not disclose such Confidential Information and shall
 * use it only in accordance with the terms of the license agreement you entered
 * into with Alibaba.com.
 */
package com.alibaba.cola.boot;

import com.alibaba.cola.command.Command;
import com.alibaba.cola.command.PostInterceptor;
import com.alibaba.cola.command.PreInterceptor;
import com.alibaba.cola.event.EventHandler;
import com.alibaba.cola.extension.Extension;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * RegisterFactory
 *
 * @author fulan.zjf 2017-11-04
 */
@Component
public class RegisterFactory{

    @Autowired
    private PreInterceptorRegister preInterceptorRegister;
    @Autowired
    private PostInterceptorRegister postInterceptorRegister;
    @Autowired
    private CommandRegister commandRegister;
    @Autowired
    private ExtensionRegister extensionRegister;
    @Autowired
    private EventRegister eventRegister;

    public RegisterI getRegister(Class<?> targetClz) {
        PreInterceptor preInterceptorAnn = targetClz.getDeclaredAnnotation(PreInterceptor.class);
        if (preInterceptorAnn != null) {
            return preInterceptorRegister;
        }
        PostInterceptor postInterceptorAnn = targetClz.getDeclaredAnnotation(PostInterceptor.class);
        if (postInterceptorAnn != null) {
            return postInterceptorRegister;
        }
        Command commandAnn = targetClz.getDeclaredAnnotation(Command.class);
        if (commandAnn != null) {
            return commandRegister;
        }
        Extension extensionAnn = targetClz.getDeclaredAnnotation(Extension.class);
        if (extensionAnn != null) {
            return extensionRegister;
        }
        EventHandler eventHandlerAnn = targetClz.getDeclaredAnnotation(EventHandler.class);
        if (eventHandlerAnn != null) {
            return eventRegister;
        }
        return null;
    }
}

BootStrap

扫描java的class,进行ioc组装；

/*
 * Copyright 2017 Alibaba.com All right reserved. This software is the
 * confidential and proprietary information of Alibaba.com ("Confidential
 * Information"). You shall not disclose such Confidential Information and shall
 * use it only in accordance with the terms of the license agreement you entered
 * into with Alibaba.com.
 */
package com.alibaba.cola.boot;

import java.util.List;
import java.util.Set;
import java.util.TreeSet;

import org.springframework.beans.factory.annotation.Autowired;

import com.alibaba.cola.exception.framework.ColaException;

import lombok.Getter;
import lombok.Setter;

/**
 * <B>应用的核心引导启动类</B>
 * <p>
 * 负责扫描在applicationContext.xml中配置的packages. 获取到CommandExecutors, intercepters, extensions, validators等
 * 交给各个注册器进行注册。
 *
 * @author fulan.zjf 2017-11-04
 */
public class Bootstrap {
    @Getter
    @Setter
    private List<String> packages;
    private ClassPathScanHandler handler;

    @Autowired
    private RegisterFactory registerFactory;

    public void init() {
        Set<Class<?>> classSet = scanConfiguredPackages();
        registerBeans(classSet);
    }

    /**
     * @param classSet
     */
    private void registerBeans(Set<Class<?>> classSet) {
        for (Class<?> targetClz : classSet) {
            RegisterI register = registerFactory.getRegister(targetClz);
            if (null != register) {
                register.doRegistration(targetClz);
            }
        }

    }

其它的核心组件的注册也在该代码中。

AbstractComponentExecutor

抽象的组件执行器，主要功能是定位到扩展类，然后执行接口的方法。

源码如下：

package com.alibaba.cola.boot;

import com.alibaba.cola.extension.BizScenario;
import com.alibaba.cola.extension.ExtensionCoordinate;

import java.util.function.Consumer;
import java.util.function.Function;

/**
 * @author fulan.zjf
 * @date 2017/12/21
 */
public abstract class AbstractComponentExecutor {

    /**
     * Execute extension with Response
     *
     * @param targetClz
     * @param bizScenario
     * @param exeFunction
     * @param <R> Response Type
     * @param <T> Parameter Type
     * @return
     */
    public <R, T> R execute(Class<T> targetClz, BizScenario bizScenario, Function<T, R> exeFunction) {
        T component = locateComponent(targetClz, bizScenario);
        return exeFunction.apply(component);
    }

    public <R, T> R execute(ExtensionCoordinate extensionCoordinate, Function<T, R> exeFunction){
        return execute((Class<T>) extensionCoordinate.getExtensionPointClass(), extensionCoordinate.getBizScenario(), exeFunction);
    }

    /**
     * Execute extension without Response
     *
     * @param targetClz
     * @param context
     * @param exeFunction
     * @param <T> Parameter Type
     */
    public <T> void executeVoid(Class<T> targetClz, BizScenario context, Consumer<T> exeFunction) {
        T component = locateComponent(targetClz, context);
        exeFunction.accept(component);
    }

    public <T> void executeVoid(ExtensionCoordinate extensionCoordinate, Consumer<T> exeFunction){
        executeVoid(extensionCoordinate.getExtensionPointClass(), extensionCoordinate.getBizScenario(), exeFunction);
    }

    protected abstract <C> C locateComponent(Class<C> targetClz, BizScenario context);
}

主要用到了java8的函数式接口Function<T,R>.

T:即系统中注册好的扩展类实例；

R即调用T的使用类的方法，执行之后的返回值。

把执行哪个方法的选择权交给了业务逻辑代码。

提供了4种不同的重载方法。

小结

通过key,value的方式进行扩展。

代码

代码点我获取！

原创不易，关注诚可贵，转发价更高！转载请注明出处，让我们互通有无，共同进步，欢迎沟通交流。

我会持续分享Java软件编程知识和程序员发展职业之路，欢迎关注，我整理了这些年编程学习的各种资源，关注公众号‘李福春持续输出’，发送'学习资料'分享给你！