Support setting class-level defaultFallback for annotation extension

sentinel-core/src/main/java/com/alibaba/csp/sentinel/annotation/SentinelResource.java

@@ -23,9 +23,10 @@
  * The annotation indicates a definition of Sentinel resource.
  *
  * @author Eric Zhao
+ * @author zhaoyuguang
  * @since 0.1.1
  */
-@Target(ElementType.METHOD)
+@Target({ElementType.METHOD, ElementType.TYPE})
 @Retention(RetentionPolicy.RUNTIME)
 @Inherited
 public @interface SentinelResource {

sentinel-extension/sentinel-annotation-aspectj/src/main/java/com/alibaba/csp/sentinel/annotation/aspectj/AbstractSentinelAspectSupport.java

@@ -33,6 +33,7 @@
  * Some common functions for Sentinel annotation aspect.
  *
  * @author Eric Zhao
+ * @author zhaoyuguang
  */
 public abstract class AbstractSentinelAspectSupport {
 
@@ -186,7 +187,13 @@ private Method extractFallbackMethod(ProceedingJoinPoint pjp, String fallbackNam
     private Method extractDefaultFallbackMethod(ProceedingJoinPoint pjp, String defaultFallback,
                                                 Class<?>[] locationClass) {
         if (StringUtil.isBlank(defaultFallback)) {
-            return null;
+            SentinelResource annotationClass = pjp.getTarget().getClass().getAnnotation(SentinelResource.class);
+            if (annotationClass != null && StringUtil.isNotBlank(annotationClass.defaultFallback())) {
+                defaultFallback = annotationClass.defaultFallback();
+                locationClass = annotationClass.fallbackClass();
+            } else {
+                return null;
+            }
         }
         boolean mustStatic = locationClass != null && locationClass.length >= 1;
         Class<?> clazz = mustStatic ? locationClass[0] : pjp.getTarget().getClass();

sentinel-extension/sentinel-annotation-aspectj/src/test/java/com/alibaba/csp/sentinel/annotation/aspectj/integration/SentinelAnnotationIntegrationTest.java

@@ -16,6 +16,7 @@
 package com.alibaba.csp.sentinel.annotation.aspectj.integration;
 
 import com.alibaba.csp.sentinel.annotation.aspectj.integration.config.AopTestConfig;
+import com.alibaba.csp.sentinel.annotation.aspectj.integration.service.BarService;
 import com.alibaba.csp.sentinel.annotation.aspectj.integration.service.FooService;
 import com.alibaba.csp.sentinel.annotation.aspectj.integration.service.FooUtil;
 import com.alibaba.csp.sentinel.node.ClusterNode;
@@ -47,6 +48,8 @@ public class SentinelAnnotationIntegrationTest extends AbstractJUnit4SpringConte
 
     @Autowired
     private FooService fooService;
+    @Autowired
+    private BarService barService;
 
     @Test
     public void testProxySuccessful() {
@@ -181,6 +184,29 @@ public void testNormalBlockHandlerAndFallback() throws Exception {
         assertThat(cn.blockQps()).isPositive();
     }
 
+    @Test
+    public void testClassLevelDefaultFallbackWithSingleParam() {
+        assertThat(barService.anotherBar(1)).isEqualTo("Hello for 1");
+        String resourceName = "apiAnotherBarWithDefaultFallback";
+        ClusterNode cn = ClusterBuilderSlot.getClusterNode(resourceName);
+        assertThat(cn).isNotNull();
+        assertThat(cn.passQps()).isPositive();
+
+        assertThat(barService.doSomething(1)).isEqualTo("do something");
+        String resourceName1 = "com.alibaba.csp.sentinel.annotation.aspectj.integration.service.BarService:doSomething(int)";
+        ClusterNode cn1 = ClusterBuilderSlot.getClusterNode(resourceName1);
+        assertThat(cn1).isNotNull();
+        assertThat(cn1.passQps()).isPositive();
+
+        assertThat(barService.anotherBar(5758)).isEqualTo("eee...");
+        assertThat(cn.exceptionQps()).isPositive();
+        assertThat(cn.blockQps()).isZero();
+
+        assertThat(barService.doSomething(5758)).isEqualTo("GlobalFallback:doFallback");
+        assertThat(cn1.exceptionQps()).isPositive();
+        assertThat(cn1.blockQps()).isZero();
+    }
+
     @Before
     public void setUp() throws Exception {
         FlowRuleManager.loadRules(new ArrayList<FlowRule>());

sentinel-extension/sentinel-annotation-aspectj/src/test/java/com/alibaba/csp/sentinel/annotation/aspectj/integration/service/BarService.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.csp.sentinel.annotation.aspectj.integration.service;
+
+import com.alibaba.csp.sentinel.annotation.SentinelResource;
+import org.springframework.stereotype.Service;
+
+/**
+ * @author zhaoyuguang
+ */
+@Service
+@SentinelResource(defaultFallback = "doFallback", fallbackClass = GlobalFallback.class)
+public class BarService {
+
+    @SentinelResource(value = "apiAnotherBarWithDefaultFallback", defaultFallback = "fallbackFunc")
+    public String anotherBar(int i) {
+        if (i == 5758) {
+            throw new IllegalArgumentException("oops");
+        }
+        return "Hello for " + i;
+    }
+
+    @SentinelResource()
+    public String doSomething(int i) {
+        if (i == 5758) {
+            throw new IllegalArgumentException("oops");
+        }
+        return "do something";
+    }
+
+    public String fallbackFunc(Throwable t) {
+        System.out.println(t.getMessage());
+        return "eee...";
+    }
+}

sentinel-extension/sentinel-annotation-aspectj/src/test/java/com/alibaba/csp/sentinel/annotation/aspectj/integration/service/GlobalFallback.java

@@ -0,0 +1,12 @@
+package com.alibaba.csp.sentinel.annotation.aspectj.integration.service;
+
+/**
+ * @author zhaoyuguang
+ */
+
+public class GlobalFallback {
+
+    public static String doFallback(Throwable t) {
+        return "GlobalFallback:doFallback";
+    }
+}