Dubbo 路由规则的过滤器实现

common/mall-spring-boot-starter-dubbo/src/main/java/cn/iocoder/mall/dubbo/config/DubboWebAutoConfiguration.java

@@ -0,0 +1,25 @@
+package cn.iocoder.mall.dubbo.config;
+
+import cn.iocoder.mall.dubbo.core.web.DubboRouterTagWebInterceptor;
+import org.springframework.beans.factory.NoSuchBeanDefinitionException;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET)
+public class DubboWebAutoConfiguration implements WebMvcConfigurer {
+
+    // ========== 拦截器相关 ==========
+
+    @Override
+    public void addInterceptors(InterceptorRegistry registry) {
+        try {
+            registry.addInterceptor(new DubboRouterTagWebInterceptor()).order(-1000);
+        } catch (NoSuchBeanDefinitionException e) {
+//            logger.warn("[addInterceptors][无法获取 AccessLogInterceptor 拦截器，因此不启动 AccessLog 的记录]");
+        }
+    }
+
+}

common/mall-spring-boot-starter-dubbo/src/main/java/cn/iocoder/mall/dubbo/core/filter/DubboRouterTagFilter.java

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+package cn.iocoder.mall.dubbo.core.filter;
+
+import cn.iocoder.common.framework.util.StringUtils;
+import cn.iocoder.mall.dubbo.core.router.DubboRouterTagContextHolder;
+import org.apache.dubbo.common.constants.CommonConstants;
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.rpc.*;
+
+/**
+ * 基于 Dubbo 标签路由规则(http://dubbo.apache.org/zh-cn/docs/user/demos/routing-rule.html)，实现如下功能：
+ * 1. 本地开发调试时，在带有 Dubbo Tag 的情况下，优先调用指定 Tag 的服务提供者。这样，我们可以将本地启动的服务提供者打上相应的 Tag，即可优先调用本地；
+ * 2. TODO 优化点：蓝绿发布、灰度发布
+ *
+ * 实现逻辑为：
+ * 1. 对于 Consumer 方，在调用 Provider 时，会将 {@link DubboRouterTagContextHolder} 中的 Tag 通过 Dubbo 隐式传参。
+ *      同时，Dubbo 自带 {@link org.apache.dubbo.rpc.cluster.router.tag.TagRouter}，会根据该参数，会选择符合该 Tag 的 Provider。
+ * 2. 对于 Provider 方，在通过 Dubbo 隐式传参获得到 Tag 时，会设置到 {@link DubboRouterTagContextHolder} 中。
+ *      这样，在 Provider 作为 Consumer 角色时，调用其它 Provider 时，可以继续实现标签路由的功能。
+ */
+@Activate(group = {CommonConstants.PROVIDER, CommonConstants.CONSUMER}, order = -1000)
+public class DubboRouterTagFilter implements Filter {
+
+    @Override
+    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
+        // 消费端
+        if (RpcContext.getContext().isConsumerSide()) {
+            // 设置 Dubbo Tag 到 Dubbo 隐式传参
+            String dubboTag = DubboRouterTagContextHolder.getTag();
+            boolean hasDubboTag = StringUtils.hasText(dubboTag);
+            if (hasDubboTag) {
+                invocation.setAttachment(CommonConstants.TAG_KEY, dubboTag);
+            }
+            // 继续调用
+            try {
+                return invoker.invoke(invocation);
+            } finally {
+                // 解决极端情况下，本地 injvm 调用时，消费端会调用 DubboRouterTagContextHolder.clear() 上下文，导致消费端也被清理了，因为在同一个 JVM 进程内。
+                if (hasDubboTag) {
+                    DubboRouterTagContextHolder.setTag(dubboTag);
+                }
+            }
+            // 提供端
+        } else {
+            // 从 Dubbo 隐式传参获得 Dubbo Tag
+            String dubboTag = invocation.getAttachment(CommonConstants.TAG_KEY);
+            boolean hasDubboTag = StringUtils.hasText(dubboTag);
+            if (hasDubboTag) {
+                invocation.setAttachment(CommonConstants.TAG_KEY, dubboTag);
+            }
+            // 继续调用
+            try {
+                return invoker.invoke(invocation);
+            } finally {
+                // 清理
+                if (hasDubboTag) {
+                    DubboRouterTagContextHolder.clear();
+                }
+            }
+        }
+    }
+
+}

common/mall-spring-boot-starter-dubbo/src/main/java/cn/iocoder/mall/dubbo/core/package-info.java

@@ -1,4 +0,0 @@
-/**
- * 占坑
- */
-package cn.iocoder.mall.dubbo.core;

common/mall-spring-boot-starter-dubbo/src/main/java/cn/iocoder/mall/dubbo/core/router/DubboRouterTagContextHolder.java

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+package cn.iocoder.mall.dubbo.core.router;
+
+/**
+ * Dubbo 路由 Tag 的上下文
+ *
+ * @see cn.iocoder.mall.dubbo.core.filter.DubboRouterTagFilter
+ * @see cn.iocoder.mall.dubbo.core.web.DubboRouterTagWebInterceptor
+ */
+public class DubboRouterTagContextHolder {
+
+    private static ThreadLocal<String> tagContext = new ThreadLocal<>();
+
+    public static void setTag(String tag) {
+        tagContext.set(tag);
+    }
+
+    public static String getTag() {
+        return tagContext.get();
+    }
+
+    public static void clear() {
+        tagContext.remove();
+    }
+
+}

common/mall-spring-boot-starter-dubbo/src/main/java/cn/iocoder/mall/dubbo/core/web/DubboRouterTagWebInterceptor.java

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+package cn.iocoder.mall.dubbo.core.web;
+
+import cn.iocoder.common.framework.util.StringUtils;
+import cn.iocoder.mall.dubbo.core.router.DubboRouterTagContextHolder;
+import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.ModelAndView;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * Dubbo 路由标签的 Web 拦截器，将请求 Header 中的 {@link #HEADER_DUBBO_TAG} 设置到 {@link DubboRouterTagContextHolder} 中。
+ *
+ * @see cn.iocoder.mall.dubbo.core.filter.DubboRouterTagFilter
+ */
+public class DubboRouterTagWebInterceptor implements HandlerInterceptor {
+
+    private static final String HEADER_DUBBO_TAG = "dubbo-tag";
+
+    @Override
+    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
+        String tag = request.getHeader(HEADER_DUBBO_TAG);
+        if (StringUtils.hasText(tag)) {
+            DubboRouterTagContextHolder.setTag(tag);
+        }
+        return true;
+    }
+
+    @Override
+    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) {
+        DubboRouterTagContextHolder.clear();
+    }
+
+}