add spring cloud sentinel circuitbreaker demo

spring-cloud-alibaba-examples/sentinel-example/sentinel-core-example/src/main/java/com/alibaba/cloud/examples/ServiceApplication.java

@@ -16,11 +16,18 @@
 
 package com.alibaba.cloud.examples;
 
+import java.util.Collections;
+
+import com.alibaba.cloud.circuitbreaker.sentinel.SentinelCircuitBreakerFactory;
+import com.alibaba.cloud.circuitbreaker.sentinel.SentinelConfigBuilder;
 import com.alibaba.cloud.sentinel.annotation.SentinelRestTemplate;
 import com.alibaba.csp.sentinel.datasource.Converter;
+import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.cloud.client.circuitbreaker.Customizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.web.client.RestTemplate;
 
@@ -31,8 +38,7 @@ import org.springframework.web.client.RestTemplate;
 public class ServiceApplication {
 
 	@Bean
-	@SentinelRestTemplate(blockHandler = "handleException",
+	@SentinelRestTemplate(blockHandler = "handleException", blockHandlerClass = ExceptionUtil.class)
-			blockHandlerClass = ExceptionUtil.class)
 	public RestTemplate restTemplate() {
 		return new RestTemplate();
 	}
@@ -47,6 +53,18 @@ public class ServiceApplication {
 		return new JsonFlowRuleListConverter();
 	}
 
+	@Bean
+	public Customizer<SentinelCircuitBreakerFactory> defaultConfig() {
+		return factory -> {
+			factory.configureDefault(
+					id -> new SentinelConfigBuilder().resourceName(id)
+							.rules(Collections.singletonList(new DegradeRule(id)
+									.setGrade(RuleConstant.DEGRADE_GRADE_RT).setCount(100)
+									.setTimeWindow(10)))
+							.build());
+		};
+	}
+
 	public static void main(String[] args) {
 		SpringApplication.run(ServiceApplication.class, args);
 	}

spring-cloud-alibaba-examples/sentinel-example/sentinel-core-example/src/main/java/com/alibaba/cloud/examples/TestController.java

@@ -19,6 +19,7 @@ package com.alibaba.cloud.examples;
 import com.alibaba.csp.sentinel.annotation.SentinelResource;
 
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cloud.client.circuitbreaker.CircuitBreakerFactory;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RestController;
 import org.springframework.web.client.RestTemplate;
@@ -32,6 +33,9 @@ public class TestController {
 	@Autowired
 	private RestTemplate restTemplate;
 
+	@Autowired
+	private CircuitBreakerFactory circuitBreakerFactory;
+
 	@GetMapping("/hello")
 	@SentinelResource("resource")
 	public String hello() {
@@ -54,4 +58,17 @@ public class TestController {
 		return restTemplate.getForObject("http://www.taobao.com/test", String.class);
 	}
 
+	@GetMapping("/slow")
+	public String slow() {
+		return circuitBreakerFactory.create("show").run(() -> {
+			try {
+				Thread.sleep(1000L);
+			}
+			catch (InterruptedException e) {
+				e.printStackTrace();
+			}
+			return "success";
+		}, throwable -> "fallback");
+	}
+
 }