Apache ShenYu源码阅读系列-Divide插件

Apache ShenYu 是一个异步的，高性能的，跨语言的，响应式的 API 网关。

ShenYu 网关使用 divide 插件来处理 http 请求。你可以查看官方文档 Http快速开始了解如何使用该插件。

本文基于shenyu-2.4.3版本进行源码分析，官网的介绍请参考 Http服务接入。

1. 服务注册

1.1 声明注册接口

使用注解@ShenyuSpringMvcClient将服务注册到网关。简单demo如下：

@RestController
@RequestMapping("/order")
@ShenyuSpringMvcClient(path = "/order")  // API注册
public class OrderController {@GetMapping("/findById")@ShenyuSpringMvcClient(path = "/findById", desc = "Find by id") // 方法注册public OrderDTO findById(@RequestParam("id") final String id) {return build(id, "hello world findById");}
}

注解定义：


/*** 作用于类和方法上*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.METHOD})
public @interface ShenyuSpringMvcClient {//注册路径String path() default "";//规则名称String ruleName() default "";//描述信息String desc() default "";//是否启用boolean enabled() default true;//注册元数据boolean registerMetaData() default false;
}

1.2 扫描注解信息

注解扫描通过SpringMvcClientBeanPostProcessor完成，它实现了BeanPostProcessor接口，是Spring提供的后置处理器。

在构造器实例化的过程中：

读取属性配置
添加注解，读取path信息
启动注册中心，向shenyu-admin注册

public class SpringMvcClientBeanPostProcessor implements BeanPostProcessor {//.../*** 构造器实例化*/public SpringMvcClientBeanPostProcessor(final PropertiesConfig clientConfig,final ShenyuClientRegisterRepository shenyuClientRegisterRepository) {// 1. 读取属性配置Properties props = clientConfig.getProps();this.appName = props.getProperty(ShenyuClientConstants.APP_NAME);this.contextPath = props.getProperty(ShenyuClientConstants.CONTEXT_PATH, "");if (StringUtils.isBlank(appName) && StringUtils.isBlank(contextPath)) {String errorMsg = "http register param must config the appName or contextPath";LOG.error(errorMsg);throw new ShenyuClientIllegalArgumentException(errorMsg);}this.isFull = Boolean.parseBoolean(props.getProperty(ShenyuClientConstants.IS_FULL, Boolean.FALSE.toString()));// 2. 添加注解mappingAnnotation.add(ShenyuSpringMvcClient.class);mappingAnnotation.add(PostMapping.class);mappingAnnotation.add(GetMapping.class);mappingAnnotation.add(DeleteMapping.class);mappingAnnotation.add(PutMapping.class);mappingAnnotation.add(RequestMapping.class);// 3. 启动注册中心publisher.start(shenyuClientRegisterRepository);}@Overridepublic Object postProcessAfterInitialization(@NonNull final Object bean, @NonNull final String beanName) throws BeansException {// 重写后置处理器逻辑return bean;}

SpringMvcClientBeanPostProcessor#postProcessAfterInitialization()

重写后置处理器逻辑：读取注解信息，构建元数据对象和URI对象，并向shenyu-admin注册。

    @Overridepublic Object postProcessAfterInitialization(@NonNull final Object bean, @NonNull final String beanName) throws BeansException {// 1. 如果是注册整个服务或者不是Controller类，就不处理if (Boolean.TRUE.equals(isFull) || !hasAnnotation(bean.getClass(), Controller.class)) {return bean;}// 2. 读取类上的注解 ShenyuSpringMvcClientfinal ShenyuSpringMvcClient beanShenyuClient = AnnotationUtils.findAnnotation(bean.getClass(), ShenyuSpringMvcClient.class);// 2.1构建superPathfinal String superPath = buildApiSuperPath(bean.getClass());// 2.2 是否注册整个类方法if (Objects.nonNull(beanShenyuClient) && superPath.contains("*")) {// 构建元数据对象，然后向shenyu-admin注册publisher.publishEvent(buildMetaDataDTO(beanShenyuClient, pathJoin(contextPath, superPath)));return bean;}// 3. 读取所有方法final Method[] methods = ReflectionUtils.getUniqueDeclaredMethods(bean.getClass());for (Method method : methods) {// 3.1 读取方法上的注解 ShenyuSpringMvcClientShenyuSpringMvcClient methodShenyuClient = AnnotationUtils.findAnnotation(method, ShenyuSpringMvcClient.class);// 如果方法上面没有注解，就用类上面的注解methodShenyuClient = Objects.isNull(methodShenyuClient) ? beanShenyuClient : methodShenyuClient;if (Objects.nonNull(methodShenyuClient)) {// 3.2 构建path信息，构建元数据对象，向shenyu-admin注册publisher.publishEvent(buildMetaDataDTO(methodShenyuClient, buildApiPath(method, superPath)));}}return bean;}

1.如果是注册整个服务或者不是Controller类，就不处理
2.读取类上的注解 ShenyuSpringMvcClient，如果是注册整个类，就在这里构建元数据对象，然后向shenyu-admin注册
3.处理方法上的注解 ShenyuSpringMvcClient，针对特定方法构建path信息，构建元数据对象，然后向shenyu-admin注册

这里有两个取path的方法，需要特别说明一下：

buildApiSuperPath()

构造SuperPath：先从类上的注解ShenyuSpringMvcClient取path属性，如果没有，就从当前类的RequestMapping注解中取path信息。

    private String buildApiSuperPath(@NonNull final Class<?> method) {// 先从类上的注解ShenyuSpringMvcClient取path属性ShenyuSpringMvcClient shenyuSpringMvcClient = AnnotationUtils.findAnnotation(method, ShenyuSpringMvcClient.class);if (Objects.nonNull(shenyuSpringMvcClient) && StringUtils.isNotBlank(shenyuSpringMvcClient.path())) {return shenyuSpringMvcClient.path();}// 从当前类的RequestMapping注解中取path信息RequestMapping requestMapping = AnnotationUtils.findAnnotation(method, RequestMapping.class);if (Objects.nonNull(requestMapping) && ArrayUtils.isNotEmpty(requestMapping.path()) && StringUtils.isNotBlank(requestMapping.path()[0])) {return requestMapping.path()[0];}return "";}

buildApiPath()

构建path：先读取方法上的注解ShenyuSpringMvcClient，如果存在就构建；否则从方法的其他注解上获取path信息；完整的path = contextPath(上下文信息)+superPath(类信息)+methodPath(方法信息)。

    private String buildApiPath(@NonNull final Method method, @NonNull final String superPath) {// 1. 读取方法上的注解ShenyuSpringMvcClientShenyuSpringMvcClient shenyuSpringMvcClient = AnnotationUtils.findAnnotation(method, ShenyuSpringMvcClient.class);// 1.1如果存在path，就构建if (Objects.nonNull(shenyuSpringMvcClient) && StringUtils.isNotBlank(shenyuSpringMvcClient.path())) {//1.2完整 path = contextPath+superPath+methodPathreturn pathJoin(contextPath, superPath, shenyuSpringMvcClient.path());}// 2.从方法的其他注解上获取path信息final String path = getPathByMethod(method);if (StringUtils.isNotBlank(path)) {// 2.1 完整的path = contextPath+superPath+methodPathreturn pathJoin(contextPath, superPath, path);}return pathJoin(contextPath, superPath);}

getPathByMethod()

从方法的其他注解上获取path信息，其他注解包括：
- ShenyuSpringMvcClient
- PostMapping
- GetMapping
- DeleteMapping
- PutMapping
- RequestMapping

private String getPathByMethod(@NonNull final Method method) {// 遍历接口注解获取path信息for (Class<? extends Annotation> mapping : mappingAnnotation) {final String pathByAnnotation = getPathByAnnotation(AnnotationUtils.findAnnotation(method, mapping), pathAttributeNames);if (StringUtils.isNotBlank(pathByAnnotation)) {return pathByAnnotation;}}return null;}

扫描注解完成后，构建元数据对象，然后将该对象发送到shenyu-admin，即可完成注册。

元数据对象

包括当前注册方法的规则信息：contextPath，appName，注册路径，描述信息，注册类型，是否启用，规则名称和是否注册元数据。

 private MetaDataRegisterDTO buildMetaDataDTO(@NonNull final ShenyuSpringMvcClient shenyuSpringMvcClient, final String path) {return MetaDataRegisterDTO.builder().contextPath(contextPath) // contextPath.appName(appName) // appName.path(path) // 注册路径，在网关规则匹配时使用.pathDesc(shenyuSpringMvcClient.desc()) // 描述信息.rpcType(RpcTypeEnum.HTTP.getName()) // divide插件，默认时http类型.enabled(shenyuSpringMvcClient.enabled()) // 是否启用规则.ruleName(StringUtils.defaultIfBlank(shenyuSpringMvcClient.ruleName(), path))//规则名称.registerMetaData(shenyuSpringMvcClient.registerMetaData()) //是否注册元数据信息.build();}

具体的注册逻辑由注册中心实现，在之前的文章中已经分析过了，这里就不再深入分析。

1.3 注册URI信息

ContextRegisterListener负责将客户端的URI信息注册到shenyu-admin，它实现了ApplicationListener接口，发生上下文刷新事件ContextRefreshedEvent时，执行onApplicationEvent()方法，实现注册逻辑。


public class ContextRegisterListener implements ApplicationListener<ContextRefreshedEvent>, BeanFactoryAware {//....../*** 构造器实例化*/public ContextRegisterListener(final PropertiesConfig clientConfig) {// 读取属性配置final Properties props = clientConfig.getProps();this.isFull = Boolean.parseBoolean(props.getProperty(ShenyuClientConstants.IS_FULL, Boolean.FALSE.toString()));this.contextPath = props.getProperty(ShenyuClientConstants.CONTEXT_PATH);if (Boolean.TRUE.equals(isFull)) {if (StringUtils.isBlank(contextPath)) {final String errorMsg = "http register param must config the contextPath";LOG.error(errorMsg);throw new ShenyuClientIllegalArgumentException(errorMsg);}}this.port = Integer.parseInt(Optional.ofNullable(props.getProperty(ShenyuClientConstants.PORT)).orElseGet(() -> "-1"));this.appName = props.getProperty(ShenyuClientConstants.APP_NAME);this.protocol = props.getProperty(ShenyuClientConstants.PROTOCOL, ShenyuClientConstants.HTTP);this.host = props.getProperty(ShenyuClientConstants.HOST);}@Overridepublic void setBeanFactory(final BeanFactory beanFactory) throws BeansException {this.beanFactory = beanFactory;}// 执行应用事件@Overridepublic void onApplicationEvent(@NonNull final ContextRefreshedEvent contextRefreshedEvent) {// 保证该方法执行一次if (!registered.compareAndSet(false, true)) {return;}// 1. 如果是注册整个服务if (Boolean.TRUE.equals(isFull)) {// 构建元数据，并注册publisher.publishEvent(buildMetaDataDTO());}try {// 获取端口信息final int mergedPort = port <= 0 ? PortUtils.findPort(beanFactory) : port;// 2. 构建URI数据，并注册publisher.publishEvent(buildURIRegisterDTO(mergedPort));} catch (ShenyuException e) {throw new ShenyuException(e.getMessage() + "please config ${shenyu.client.http.props.port} in xml/yml !");}}// 构建URI数据private URIRegisterDTO buildURIRegisterDTO(final int port) {return URIRegisterDTO.builder().contextPath(this.contextPath) // contextPath.appName(appName) // appName.protocol(protocol) // 服务使用的协议.host(IpUtils.isCompleteHost(this.host) ? this.host : IpUtils.getHost(this.host)) //主机.port(port) // 端口.rpcType(RpcTypeEnum.HTTP.getName()) // divide插件，默认注册http类型.build();}// 构建元数据private MetaDataRegisterDTO buildMetaDataDTO() {return MetaDataRegisterDTO.builder().contextPath(contextPath).appName(appName).path(contextPath).rpcType(RpcTypeEnum.HTTP.getName()).enabled(true).ruleName(contextPath).build();}
}

1.4 处理注册信息

客户端通过注册中心注册的元数据和URI数据，在shenyu-admin进行处理，负责存储到数据库和同步给shenyu网关。Divide插件的客户端注册处理逻辑在ShenyuClientRegisterDivideServiceImpl中。继承关系如下：

ShenyuClientRegisterService：客户端注册服务，顶层接口；
FallbackShenyuClientRegisterService：注册失败，提供重试操作；
AbstractShenyuClientRegisterServiceImpl：抽象类，实现部分公共注册逻辑；
AbstractContextPathRegisterService：抽象类，负责注册ContextPath；
ShenyuClientRegisterDivideServiceImpl：实现Divide插件的注册；

1.4.1 注册服务

org.apache.shenyu.admin.service.register.AbstractShenyuClientRegisterServiceImpl#register()

客户端通过注册中心注册的元数据MetaDataRegisterDTO对象在shenyu-admin的register()方法被接送到。

   @Overridepublic String register(final MetaDataRegisterDTO dto) {//1. 注册选择器String selectorHandler = selectorHandler(dto);String selectorId = selectorService.registerDefault(dto, PluginNameAdapter.rpcTypeAdapter(rpcType()), selectorHandler);//2. 注册规则String ruleHandler = ruleHandler();RuleDTO ruleDTO = buildRpcDefaultRuleDTO(selectorId, dto, ruleHandler);ruleService.registerDefault(ruleDTO);//3. 注册元数据registerMetadata(dto);//4. 注册ContextPathString contextPath = dto.getContextPath();if (StringUtils.isNotEmpty(contextPath)) {registerContextPath(dto);}return ShenyuResultMessage.SUCCESS;}

1.4.1.1 注册选择器

org.apache.shenyu.admin.service.impl.SelectorServiceImpl#registerDefault()

构建contextPath，查找选择器信息是否存在，如果存在就返回id；不存在就创建默认的选择器信息。

    @Overridepublic String registerDefault(final MetaDataRegisterDTO dto, final String pluginName, final String selectorHandler) {// 构建contextPathString contextPath = ContextPathUtils.buildContextPath(dto.getContextPath(), dto.getAppName());// 通过名称查找选择器信息是否存在SelectorDO selectorDO = findByNameAndPluginName(contextPath, pluginName);if (Objects.isNull(selectorDO)) {// 不存在就创建默认的选择器信息return registerSelector(contextPath, pluginName, selectorHandler);}return selectorDO.getId();}

默认选择器信息

在这里构建默认选择器信息及其条件属性。

   //注册选择器private String registerSelector(final String contextPath, final String pluginName, final String selectorHandler) {//构建选择器SelectorDTO selectorDTO = buildSelectorDTO(contextPath, pluginMapper.selectByName(pluginName).getId());selectorDTO.setHandle(selectorHandler);//注册默认选择器return registerDefault(selectorDTO);}//构建选择器private SelectorDTO buildSelectorDTO(final String contextPath, final String pluginId) {//构建默认选择器SelectorDTO selectorDTO = buildDefaultSelectorDTO(contextPath);selectorDTO.setPluginId(pluginId);//构建默认选择器的条件属性selectorDTO.setSelectorConditions(buildDefaultSelectorConditionDTO(contextPath));return selectorDTO;}

构建默认选择器

private SelectorDTO buildDefaultSelectorDTO(final String name) {return SelectorDTO.builder().name(name) // 名称.type(SelectorTypeEnum.CUSTOM_FLOW.getCode()) // 默认类型自定义.matchMode(MatchModeEnum.AND.getCode()) //默认匹配方式 and.enabled(Boolean.TRUE)  //默认启开启.loged(Boolean.TRUE)  //默认记录日志.continued(Boolean.TRUE) //默认继续后续选择器.sort(1) //默认顺序1.build();
}

构建默认选择器条件属性

private List<SelectorConditionDTO> buildDefaultSelectorConditionDTO(final String contextPath) {SelectorConditionDTO selectorConditionDTO = new SelectorConditionDTO();selectorConditionDTO.setParamType(ParamTypeEnum.URI.getName()); // 默认参数类型URIselectorConditionDTO.setParamName("/");selectorConditionDTO.setOperator(OperatorEnum.MATCH.getAlias()); // 默认匹配策略 matchselectorConditionDTO.setParamValue(contextPath + AdminConstants.URI_SUFFIX); // 默认值 /contextPath/**return Collections.singletonList(selectorConditionDTO);
}

注册默认选择器

@Override
public String registerDefault(final SelectorDTO selectorDTO) {//选择器信息SelectorDO selectorDO = SelectorDO.buildSelectorDO(selectorDTO);//选择器条件属性List<SelectorConditionDTO> selectorConditionDTOs = selectorDTO.getSelectorConditions();if (StringUtils.isEmpty(selectorDTO.getId())) {// 向数据库插入选择器信息selectorMapper.insertSelective(selectorDO);// 向数据库插入选择器条件属性selectorConditionDTOs.forEach(selectorConditionDTO -> {selectorConditionDTO.setSelectorId(selectorDO.getId());            selectorConditionMapper.insertSelective(SelectorConditionDO.buildSelectorConditionDO(selectorConditionDTO));});}// 发布同步事件，向网关同步选择信息及其条件属性publishEvent(selectorDO, selectorConditionDTOs);return selectorDO.getId();
}

1.4.1.2 注册规则

在注册服务的第二步中，开始构建默认规则，然后注册规则。

@Overridepublic String register(final MetaDataRegisterDTO dto) {//1. 注册选择器//......//2. 注册规则// 默认规则处理属性String ruleHandler = ruleHandler();// 构建默认规则信息RuleDTO ruleDTO = buildRpcDefaultRuleDTO(selectorId, dto, ruleHandler);// 注册规则ruleService.registerDefault(ruleDTO);//3. 注册元数据//......//4. 注册ContextPath//......return ShenyuResultMessage.SUCCESS;}

默认规则处理属性

    @Overrideprotected String ruleHandler() {// 默认规则处理属性return new DivideRuleHandle().toJson();}

Divide插件默认规则处理属性


public class DivideRuleHandle implements RuleHandle {/*** 负载均衡：默认随机*/private String loadBalance = LoadBalanceEnum.RANDOM.getName();/*** 重试策略：默认重试当前服务*/private String retryStrategy = RetryEnum.CURRENT.getName();/*** 重试次数：默认3次*/private int retry = 3;/*** 调用超时：默认 3000*/private long timeout = Constants.TIME_OUT;/*** header最大值：10240*/private long headerMaxSize = Constants.HEADER_MAX_SIZE;/*** request最大值：102400*/private long requestMaxSize = Constants.REQUEST_MAX_SIZE;
}

构建默认规则信息

  // 构建默认规则信息private RuleDTO buildRpcDefaultRuleDTO(final String selectorId, final MetaDataRegisterDTO metaDataDTO, final String ruleHandler) {return buildRuleDTO(selectorId, ruleHandler, metaDataDTO.getRuleName(), metaDataDTO.getPath());}//  构建默认规则信息private RuleDTO buildRuleDTO(final String selectorId, final String ruleHandler, final String ruleName, final String path) {RuleDTO ruleDTO = RuleDTO.builder().selectorId(selectorId) //关联的选择器id.name(ruleName) //规则名称.matchMode(MatchModeEnum.AND.getCode()) // 默认匹配模式 and.enabled(Boolean.TRUE) // 默认开启.loged(Boolean.TRUE) //默认记录日志.sort(1) //默认顺序 1.handle(ruleHandler).build();RuleConditionDTO ruleConditionDTO = RuleConditionDTO.builder().paramType(ParamTypeEnum.URI.getName()) // 默认参数类型URI.paramName("/").paramValue(path) //参数值path.build();if (path.indexOf("*") > 1) {ruleConditionDTO.setOperator(OperatorEnum.MATCH.getAlias()); //如果path中有*，操作类型则默认为 match} else {ruleConditionDTO.setOperator(OperatorEnum.EQ.getAlias()); // 否则，默认操作类型 = }ruleDTO.setRuleConditions(Collections.singletonList(ruleConditionDTO));return ruleDTO;}

org.apache.shenyu.admin.service.impl.RuleServiceImpl#registerDefault()

注册规则：向数据库插入记录，并向网关发布事件，进行数据同步。

@Overridepublic String registerDefault(final RuleDTO ruleDTO) {RuleDO exist = ruleMapper.findBySelectorIdAndName(ruleDTO.getSelectorId(), ruleDTO.getName());if (Objects.nonNull(exist)) {return "";}RuleDO ruleDO = RuleDO.buildRuleDO(ruleDTO);List<RuleConditionDTO> ruleConditions = ruleDTO.getRuleConditions();if (StringUtils.isEmpty(ruleDTO.getId())) {// 向数据库插入规则信息ruleMapper.insertSelective(ruleDO);//向数据库插入规则体条件属性ruleConditions.forEach(ruleConditionDTO -> {ruleConditionDTO.setRuleId(ruleDO.getId());                ruleConditionMapper.insertSelective(RuleConditionDO.buildRuleConditionDO(ruleConditionDTO));});}// 向网关发布事件，进行数据同步publishEvent(ruleDO, ruleConditions);return ruleDO.getId();}

1.4.1.3 注册元数据

   @Overridepublic String register(final MetaDataRegisterDTO dto) {//1. 注册选择器//......//2. 注册规则//......//3. 注册元数据registerMetadata(dto);//4. 注册ContextPath//......return ShenyuResultMessage.SUCCESS;}

org.apache.shenyu.admin.service.register.ShenyuClientRegisterDivideServiceImpl#registerMetadata()

插入或更新元数据，然后发布同步事件到网关。

@Overrideprotected void registerMetadata(final MetaDataRegisterDTO dto) {if (dto.isRegisterMetaData()) { // 如果注册元数据// 获取metaDataServiceMetaDataService metaDataService = getMetaDataService();// 元数据是否存在MetaDataDO exist = metaDataService.findByPath(dto.getPath());// 插入或更新元数据metaDataService.saveOrUpdateMetaData(exist, dto);}}@Overridepublic void saveOrUpdateMetaData(final MetaDataDO exist, final MetaDataRegisterDTO metaDataDTO) {DataEventTypeEnum eventType;// 数据类型转换 DTO->DOMetaDataDO metaDataDO = MetaDataTransfer.INSTANCE.mapRegisterDTOToEntity(metaDataDTO);// 插入数据if (Objects.isNull(exist)) {Timestamp currentTime = new Timestamp(System.currentTimeMillis());metaDataDO.setId(UUIDUtils.getInstance().generateShortUuid());metaDataDO.setDateCreated(currentTime);metaDataDO.setDateUpdated(currentTime);metaDataMapper.insert(metaDataDO);eventType = DataEventTypeEnum.CREATE;} else {// 更新数据metaDataDO.setId(exist.getId());metaDataMapper.update(metaDataDO);eventType = DataEventTypeEnum.UPDATE;}// 发布同步事件到网关eventPublisher.publishEvent(new DataChangedEvent(ConfigGroupEnum.META_DATA, eventType,Collections.singletonList(MetaDataTransfer.INSTANCE.mapToData(metaDataDO))));}

1.4.1.4 注册ContextPath

   @Overridepublic String register(final MetaDataRegisterDTO dto) {//1. 注册选择器//......//2. 注册规则//......//3. 注册元数据//......//4. 注册ContextPathString contextPath = dto.getContextPath();if (StringUtils.isNotEmpty(contextPath)) {registerContextPath(dto);}return ShenyuResultMessage.SUCCESS;}

org.apache.shenyu.admin.service.register.AbstractContextPathRegisterService#registerContextPath()

    @Overridepublic void registerContextPath(final MetaDataRegisterDTO dto) {// 设置选择器的contextPathString contextPathSelectorId = getSelectorService().registerDefault(dto, PluginEnum.CONTEXT_PATH.getName(), "");ContextMappingRuleHandle handle = new ContextMappingRuleHandle();handle.setContextPath(PathUtils.decoratorContextPath(dto.getContextPath()));// 设置规则的contextPathgetRuleService().registerDefault(buildContextPathDefaultRuleDTO(contextPathSelectorId, dto, handle.toJson()));}

1.4.2 注册URI

org.apache.shenyu.admin.service.register.FallbackShenyuClientRegisterService#registerURI()

服务端收到客户端注册的URI信息后，进行处理。

    @Overridepublic String registerURI(final String selectorName, final List<URIRegisterDTO> uriList) {String result;String key = key(selectorName);try {this.removeFallBack(key);// 注册URIresult = this.doRegisterURI(selectorName, uriList);logger.info("Register success: {},{}", selectorName, uriList);} catch (Exception ex) {logger.warn("Register exception: cause:{}", ex.getMessage());result = "";// 注册失败后，进行重试this.addFallback(key, new FallbackHolder(selectorName, uriList));}return result;}

org.apache.shenyu.admin.service.register.AbstractShenyuClientRegisterServiceImpl#doRegisterURI()

从客户端注册的URI中获取有效的URI，更新对应的选择器handle属性，向网关发送选择器更新事件。

@Overridepublic String doRegisterURI(final String selectorName, final List<URIRegisterDTO> uriList) {//参数检查if (CollectionUtils.isEmpty(uriList)) {return "";}//获取选择器信息SelectorDO selectorDO = selectorService.findByNameAndPluginName(selectorName, PluginNameAdapter.rpcTypeAdapter(rpcType()));if (Objects.isNull(selectorDO)) {throw new ShenyuException("doRegister Failed to execute,wait to retry.");}// 获取有效的URIList<URIRegisterDTO> validUriList = uriList.stream().filter(dto -> Objects.nonNull(dto.getPort()) && StringUtils.isNotBlank(dto.getHost())).collect(Collectors.toList());// 构建选择器的handle属性String handler = buildHandle(validUriList, selectorDO);if (handler != null) {selectorDO.setHandle(handler);SelectorData selectorData = selectorService.buildByName(selectorName, PluginNameAdapter.rpcTypeAdapter(rpcType()));selectorData.setHandle(handler);// 向数据库更新选择器的handle属性selectorService.updateSelective(selectorDO);// 向网关发送选择器更新事件eventPublisher.publishEvent(new DataChangedEvent(ConfigGroupEnum.SELECTOR, DataEventTypeEnum.UPDATE, Collections.singletonList(selectorData)));}return ShenyuResultMessage.SUCCESS;}

关于服务注册的源码分析就以及完成了，分析流程图如下：

接下来就分析divide插件是如何根据这些信息向http服务发起调用。

2. 服务调用

divide插件是网关用于处理 http协议请求的核心处理插件。

以官网提供的案例 Http快速开始为例，一个直连请求如下：

GET http://localhost:8189/order/findById?id=100
Accept: application/json

通过ShenYu网关代理后，请求如下：

GET http://localhost:9195/http/order/findById?id=100
Accept: application/json

通过ShenYu网关代理后的服务仍然能够请求到之前的服务，在这里起作用的就是divide插件。类继承关系如下：

ShenyuPlugin：顶层接口，定义接口方法；
AbstractShenyuPlugin：抽象类，实现插件共有逻辑；
DividePlugin：Divide插件。

2.1 接收请求

通过ShenYu网关代理后，请求入口是ShenyuWebHandler，它实现了org.springframework.web.server.WebHandler接口。

public final class ShenyuWebHandler implements WebHandler, ApplicationListener<SortPluginEvent> {//....../*** 处理web请求*/@Overridepublic Mono<Void> handle(@NonNull final ServerWebExchange exchange) {// 执行默认插件链Mono<Void> execute = new DefaultShenyuPluginChain(plugins).execute(exchange);if (scheduled) {return execute.subscribeOn(scheduler);}return execute;}private static class DefaultShenyuPluginChain implements ShenyuPluginChain {private int index;private final List<ShenyuPlugin> plugins;/*** 实例化默认插件链*/DefaultShenyuPluginChain(final List<ShenyuPlugin> plugins) {this.plugins = plugins;}/*** 执行每个插件.*/@Overridepublic Mono<Void> execute(final ServerWebExchange exchange) {return Mono.defer(() -> {if (this.index < plugins.size()) {// 获取当前执行插件ShenyuPlugin plugin = plugins.get(this.index++);// 是否跳过当前插件boolean skip = plugin.skip(exchange);if (skip) {// 如果跳过就执行下一个return this.execute(exchange);}// 执行当前插件return plugin.execute(exchange, this);}return Mono.empty();});}}
}

2.2 匹配规则

org.apache.shenyu.plugin.base.AbstractShenyuPlugin#execute()

在execute()方法中执行选择器和规则的匹配逻辑。

匹配选择器；
匹配规则；
执行插件。

@Overridepublic Mono<Void> execute(final ServerWebExchange exchange, final ShenyuPluginChain chain) {// 插件名称String pluginName = named();// 插件信息PluginData pluginData = BaseDataCache.getInstance().obtainPluginData(pluginName);if (pluginData != null && pluginData.getEnabled()) {// 选择器信息final Collection<SelectorData> selectors = BaseDataCache.getInstance().obtainSelectorData(pluginName);if (CollectionUtils.isEmpty(selectors)) {return handleSelectorIfNull(pluginName, exchange, chain);}// 匹配选择器SelectorData selectorData = matchSelector(exchange, selectors);if (Objects.isNull(selectorData)) {return handleSelectorIfNull(pluginName, exchange, chain);}selectorLog(selectorData, pluginName);// 规则信息List<RuleData> rules = BaseDataCache.getInstance().obtainRuleData(selectorData.getId());if (CollectionUtils.isEmpty(rules)) {return handleRuleIfNull(pluginName, exchange, chain);}// 匹配规则RuleData rule;if (selectorData.getType() == SelectorTypeEnum.FULL_FLOW.getCode()) {//get lastrule = rules.get(rules.size() - 1);} else {rule = matchRule(exchange, rules);}if (Objects.isNull(rule)) {return handleRuleIfNull(pluginName, exchange, chain);}ruleLog(rule, pluginName);// 执行插件return doExecute(exchange, chain, selectorData, rule);}return chain.execute(exchange);}

2.3 执行divide插件

org.apache.shenyu.plugin.divide.DividePlugin#doExecute()

在doExecute()方法中执行divide插件的具体逻辑：

校验header大小；
校验request大小；
获取服务列表；
实现负载均衡；
设置请求url，超时时间，重试策略。

@Overrideprotected Mono<Void> doExecute(final ServerWebExchange exchange, final ShenyuPluginChain chain, final SelectorData selector, final RuleData rule) {// 获取上下文信息ShenyuContext shenyuContext = exchange.getAttribute(Constants.CONTEXT);assert shenyuContext != null;// 获取规则的handle属性DivideRuleHandle ruleHandle = DividePluginDataHandler.CACHED_HANDLE.get().obtainHandle(CacheKeyUtils.INST.getKey(rule));long headerSize = 0;// 校验header大小for (List<String> multiHeader : exchange.getRequest().getHeaders().values()) {for (String value : multiHeader) {headerSize += value.getBytes(StandardCharsets.UTF_8).length;}}if (headerSize > ruleHandle.getHeaderMaxSize()) {LOG.error("request header is too large");Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.REQUEST_HEADER_TOO_LARGE, null);return WebFluxResultUtils.result(exchange, error);}// 校验request大小if (exchange.getRequest().getHeaders().getContentLength() > ruleHandle.getRequestMaxSize()) {LOG.error("request entity is too large");Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.REQUEST_ENTITY_TOO_LARGE, null);return WebFluxResultUtils.result(exchange, error);}// 获取服务列表upstreamListList<Upstream> upstreamList = UpstreamCacheManager.getInstance().findUpstreamListBySelectorId(selector.getId());if (CollectionUtils.isEmpty(upstreamList)) {LOG.error("divide upstream configuration error： {}", rule);Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.CANNOT_FIND_HEALTHY_UPSTREAM_URL, null);return WebFluxResultUtils.result(exchange, error);}// 请求ipString ip = Objects.requireNonNull(exchange.getRequest().getRemoteAddress()).getAddress().getHostAddress();// 实现负载均衡Upstream upstream = LoadBalancerFactory.selector(upstreamList, ruleHandle.getLoadBalance(), ip);if (Objects.isNull(upstream)) {LOG.error("divide has no upstream");Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.CANNOT_FIND_HEALTHY_UPSTREAM_URL, null);return WebFluxResultUtils.result(exchange, error);}// 设置urlString domain = upstream.buildDomain();exchange.getAttributes().put(Constants.HTTP_DOMAIN, domain);// 设置超时时间exchange.getAttributes().put(Constants.HTTP_TIME_OUT, ruleHandle.getTimeout());exchange.getAttributes().put(Constants.HTTP_RETRY, ruleHandle.getRetry());// 设置重试策略exchange.getAttributes().put(Constants.RETRY_STRATEGY, ruleHandle.getRetryStrategy());exchange.getAttributes().put(Constants.LOAD_BALANCE, ruleHandle.getLoadBalance());exchange.getAttributes().put(Constants.DIVIDE_SELECTOR_ID, selector.getId());return chain.execute(exchange);}

2.4 发起请求

默认由WebClientPlugin向http服务发起调用请求，类继承关系如下：

ShenyuPlugin：顶层插件，定义插件方法；
AbstractHttpClientPlugin：抽象类，实现请求调用的公共逻辑；
WebClientPlugin：通过WebClient发起请求；
NettyHttpClientPlugin：通过Netty发起请求。

发起请求调用：

org.apache.shenyu.plugin.httpclient.AbstractHttpClientPlugin#execute()

在execute()方法中发起请求调用：

获取指定的超时时间，重试次数
发起请求
根据指定的重试策略进行失败后重试操作


public abstract class AbstractHttpClientPlugin<R> implements ShenyuPlugin {protected static final Logger LOG = LoggerFactory.getLogger(AbstractHttpClientPlugin.class);@Overridepublic final Mono<Void> execute(final ServerWebExchange exchange, final ShenyuPluginChain chain) {// 获取上下文信息final ShenyuContext shenyuContext = exchange.getAttribute(Constants.CONTEXT);assert shenyuContext != null;// 获取urifinal URI uri = exchange.getAttribute(Constants.HTTP_URI);if (Objects.isNull(uri)) {Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.CANNOT_FIND_URL, null);return WebFluxResultUtils.result(exchange, error);}// 获取指定的超时时间final long timeout = (long) Optional.ofNullable(exchange.getAttribute(Constants.HTTP_TIME_OUT)).orElse(3000L);final Duration duration = Duration.ofMillis(timeout);// 获取指定重试次数final int retryTimes = (int) Optional.ofNullable(exchange.getAttribute(Constants.HTTP_RETRY)).orElse(0);// 获取指定的重试策略final String retryStrategy = (String) Optional.ofNullable(exchange.getAttribute(Constants.RETRY_STRATEGY)).orElseGet(RetryEnum.CURRENT::getName);LOG.info("The request urlPath is {}, retryTimes is {}, retryStrategy is {}", uri.toASCIIString(), retryTimes, retryStrategy);// 构建headerfinal HttpHeaders httpHeaders = buildHttpHeaders(exchange);// 发起请求final Mono<R> response = doRequest(exchange, exchange.getRequest().getMethodValue(), uri, httpHeaders, exchange.getRequest().getBody()).timeout(duration, Mono.error(new TimeoutException("Response took longer than timeout: " + duration))).doOnError(e -> LOG.error(e.getMessage(), e));// 重试策略CURRENT，对当前服务进行重试if (RetryEnum.CURRENT.getName().equals(retryStrategy)) {//old version of DividePlugin and SpringCloudPlugin will run on thisreturn response.retryWhen(Retry.anyOf(TimeoutException.class, ConnectTimeoutException.class, ReadTimeoutException.class, IllegalStateException.class).retryMax(retryTimes).backoff(Backoff.exponential(Duration.ofMillis(200), Duration.ofSeconds(20), 2, true))).onErrorMap(TimeoutException.class, th -> new ResponseStatusException(HttpStatus.GATEWAY_TIMEOUT, th.getMessage(), th)).flatMap((Function<Object, Mono<? extends Void>>) o -> chain.execute(exchange));}// 对其他服务进行重试// 排除已经调用过的服务final Set<URI> exclude = Sets.newHashSet(uri);// 请求重试return resend(response, exchange, duration, httpHeaders, exclude, retryTimes).onErrorMap(TimeoutException.class, th -> new ResponseStatusException(HttpStatus.GATEWAY_TIMEOUT, th.getMessage(), th)).flatMap((Function<Object, Mono<? extends Void>>) o -> chain.execute(exchange));}private Mono<R> resend(final Mono<R> clientResponse,final ServerWebExchange exchange,final Duration duration,final HttpHeaders httpHeaders,final Set<URI> exclude,final int retryTimes) {Mono<R> result = clientResponse;// 根据指定的重试次数进行重试for (int i = 0; i < retryTimes; i++) {result = resend(result, exchange, duration, httpHeaders, exclude);}return result;}private Mono<R> resend(final Mono<R> response,final ServerWebExchange exchange,final Duration duration,final HttpHeaders httpHeaders,final Set<URI> exclude) {return response.onErrorResume(th -> {final String selectorId = exchange.getAttribute(Constants.DIVIDE_SELECTOR_ID);final String loadBalance = exchange.getAttribute(Constants.LOAD_BALANCE);//查询可用服务final List<Upstream> upstreamList = UpstreamCacheManager.getInstance().findUpstreamListBySelectorId(selectorId).stream().filter(data -> {final String trimUri = data.getUrl().trim();for (URI needToExclude : exclude) {// exclude already calledif ((needToExclude.getHost() + ":" + needToExclude.getPort()).equals(trimUri)) {return false;}}return true;}).collect(Collectors.toList());if (CollectionUtils.isEmpty(upstreamList)) {// no need to retry anymorereturn Mono.error(new ShenyuException(ShenyuResultEnum.CANNOT_FIND_HEALTHY_UPSTREAM_URL_AFTER_FAILOVER.getMsg()));}// 请求ipfinal String ip = Objects.requireNonNull(exchange.getRequest().getRemoteAddress()).getAddress().getHostAddress();// 实现负载均衡final Upstream upstream = LoadBalancerFactory.selector(upstreamList, loadBalance, ip);if (Objects.isNull(upstream)) {// no need to retry anymorereturn Mono.error(new ShenyuException(ShenyuResultEnum.CANNOT_FIND_HEALTHY_UPSTREAM_URL_AFTER_FAILOVER.getMsg()));}final URI newUri = RequestUrlUtils.buildRequestUri(exchange, upstream.buildDomain());// 排除已经调用的uriexclude.add(newUri);// 进行再次调用return doRequest(exchange, exchange.getRequest().getMethodValue(), newUri, httpHeaders, exchange.getRequest().getBody()).timeout(duration, Mono.error(new TimeoutException("Response took longer than timeout: " + duration))).doOnError(e -> LOG.error(e.getMessage(), e));});}//......
}

org.apache.shenyu.plugin.httpclient.WebClientPlugin#doRequest()

在doRequest()方法中通过webClient发起真正的请求调用。


@Overrideprotected Mono<ClientResponse> doRequest(final ServerWebExchange exchange, final String httpMethod, final URI uri,final HttpHeaders httpHeaders, final Flux<DataBuffer> body) {return webClient.method(HttpMethod.valueOf(httpMethod)).uri(uri) //请求uri.headers(headers -> headers.addAll(httpHeaders)) // 请求header.body(BodyInserters.fromDataBuffers(body)).exchange() // 发起请求.doOnSuccess(res -> {if (res.statusCode().is2xxSuccessful()) { // 成功exchange.getAttributes().put(Constants.CLIENT_RESPONSE_RESULT_TYPE, ResultEnum.SUCCESS.getName());} else { // 失败exchange.getAttributes().put(Constants.CLIENT_RESPONSE_RESULT_TYPE, ResultEnum.ERROR.getName());}exchange.getResponse().setStatusCode(res.statusCode());exchange.getAttributes().put(Constants.CLIENT_RESPONSE_ATTR, res);});}

2.5 处理响应结果

org.apache.shenyu.plugin.response.ResponsePlugin#execute()

响应结果由ResponsePlugin插件处理。

    @Overridepublic Mono<Void> execute(final ServerWebExchange exchange, final ShenyuPluginChain chain) {ShenyuContext shenyuContext = exchange.getAttribute(Constants.CONTEXT);assert shenyuContext != null;// 根据rpc类型处理结果return writerMap.get(shenyuContext.getRpcType()).writeWith(exchange, chain);}

处理类型由MessageWriter决定，类继承关系如下：

MessageWriter：接口，定义消息处理方法；
NettyClientMessageWriter：处理Netty调用结果；
RPCMessageWriter：处理RPC调用结果；
WebClientMessageWriter：处理WebClient调用结果；

默认是通过WebCient发起http请求。

org.apache.shenyu.plugin.response.strategy.WebClientMessageWriter#writeWith()

在writeWith()方法中处理响应结果。

@Overridepublic Mono<Void> writeWith(final ServerWebExchange exchange, final ShenyuPluginChain chain) {return chain.execute(exchange).then(Mono.defer(() -> {// 获取响应ServerHttpResponse response = exchange.getResponse();ClientResponse clientResponse = exchange.getAttribute(Constants.CLIENT_RESPONSE_ATTR);if (Objects.isNull(clientResponse)) {Object error = ShenyuResultWrap.error(exchange, ShenyuResultEnum.SERVICE_RESULT_ERROR, null);return WebFluxResultUtils.result(exchange, error);}//获取cookies和headersresponse.getCookies().putAll(clientResponse.cookies());response.getHeaders().putAll(clientResponse.headers().asHttpHeaders());// image, pdf or stream does not do format processing.// 处理特殊响应类型if (clientResponse.headers().contentType().isPresent()) {final String media = clientResponse.headers().contentType().get().toString().toLowerCase();if (media.matches(COMMON_BIN_MEDIA_TYPE_REGEX)) {return response.writeWith(clientResponse.body(BodyExtractors.toDataBuffers())).doOnCancel(() -> clean(exchange));}}// 处理一般响应类型clientResponse = ResponseUtils.buildClientResponse(response, clientResponse.body(BodyExtractors.toDataBuffers()));return clientResponse.bodyToMono(byte[].class).flatMap(originData -> WebFluxResultUtils.result(exchange, originData)).doOnCancel(() -> clean(exchange));}));}

分析至此，关于Divide插件的源码分析就完成了，分析流程图如下：

3. 小结

本文源码分析从http服务注册开始，到divide插件的服务调用。divide插件主要用来处理http请求。有些源码没有进入深入分析，比如负载均衡的实现，服务探活，将在后续继续分析。