哨兵流控规则对应 Controller、Service 服务示例

sentinel-sample/.mvn/wrapper/MavenWrapperDownloader.java

@@ -13,9 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import java.net.*;
-import java.io.*;
-import java.nio.channels.*;
 import java.util.Properties;
 
 public class MavenWrapperDownloader {

sentinel-sample/src/main/java/com/example/demo/config/BlockExceptionHandler.java

@@ -0,0 +1,25 @@
+package com.example.demo.config;
+
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * 哨兵流控规则异常处理器
+ *
+ * @author yclimb
+ * @date 2020/10/12
+ */
+public interface BlockExceptionHandler {
+
+    /**
+     * 在此处处理限流异常，可以跳转到指定页面或返回指定的内容
+     *
+     * @param request req
+     * @param response resp
+     * @param e e
+     * @throws Exception e
+     */
+    void handle(HttpServletRequest request, HttpServletResponse response, BlockException e) throws Exception;
+}

sentinel-sample/src/main/java/com/example/demo/config/SentinelWebConfig.java

@@ -0,0 +1,29 @@
+package com.example.demo.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.io.PrintWriter;
+
+/**
+ * 哨兵流控规则异常处理配置项(流控规则对应 Controller 中的方法)
+ *
+ * @author yclimb
+ * @date 2020/10/12
+ */
+@Configuration
+public class SentinelWebConfig {
+
+    @Bean
+    public BlockExceptionHandler sentinelBlockExceptionHandler() {
+        return (request, response, e) -> {
+            // 429 Too Many Requests
+            response.setStatus(429);
+
+            PrintWriter out = response.getWriter();
+            out.print("Oops, blocked by Sentinel: " + e.getClass().getSimpleName());
+            out.flush();
+            out.close();
+        };
+    }
+}

sentinel-sample/src/main/java/com/example/demo/controller/TestController.java

@@ -1,10 +1,38 @@
 package com.example.demo.controller;
 
+import com.example.demo.service.TestService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RestController;
+
 /**
- * 测试
+ * 测试控制层
  *
  * @author yclimb
  * @date 2020/10/12
  */
+@RestController
 public class TestController {
+
+    @Autowired
+    private TestService testService;
+
+    @GetMapping("/test")
+    public void test() {
+        testService.test();
+    }
+
+    @GetMapping("/hello/{name}")
+    public String hello(@PathVariable String name) {
+        /*String str = testService.hello(111L);
+        System.out.println(str);*/
+        return testService.sayHello(name);
+    }
+
+    @GetMapping("/hello")
+    public void hello() {
+        testService.hello();
+    }
+
 }

sentinel-sample/src/main/java/com/example/demo/service/TestService.java

@@ -0,0 +1,110 @@
+package com.example.demo.service;
+
+import com.alibaba.csp.sentinel.Entry;
+import com.alibaba.csp.sentinel.SphU;
+import com.alibaba.csp.sentinel.annotation.SentinelResource;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
+import com.example.demo.util.ExceptionUtil;
+import org.springframework.stereotype.Service;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * 测试服务层(流控规则对应 Service 中的方法)
+ *
+ * @author yclimb
+ * @date 2020/10/12
+ */
+@Service
+public class TestService {
+
+    /**
+     * 自定义流控规则，手动代码实现
+     */
+    public void hello() {
+        initFlowRules();
+
+        // 循环30次
+        int i = 30;
+        while (i > 0) {
+            // 1.5.0 版本开始可以直接利用 try-with-resources 特性，自动 exit entry
+            try (Entry entry = SphU.entry("HelloWorld")) {
+                // 被保护的逻辑
+                System.out.println(i + ":hello world");
+            } catch (BlockException ex) {
+                // 处理被流控的逻辑
+                System.out.println(i + "blocked!");
+            }
+            i--;
+        }
+    }
+
+    /**
+     * 初始化流控规则，用于 hello 自定义流控规则方法使用
+     */
+    private static void initFlowRules(){
+        List<FlowRule> rules = new ArrayList<>();
+        FlowRule rule = new FlowRule();
+        rule.setResource("HelloWorld");
+        rule.setGrade(RuleConstant.FLOW_GRADE_QPS);
+        // Set limit QPS to 20.
+        rule.setCount(20);
+        rules.add(rule);
+        FlowRuleManager.loadRules(rules);
+    }
+
+    /**
+     * 哨兵自定义异常类
+     * 对应的 `handleException` 函数需要位于 `ExceptionUtil` 类中，并且必须为 static 函数.
+     */
+    @SentinelResource(value = "test", blockHandler = "handleException", blockHandlerClass = {ExceptionUtil.class})
+    public void test() {
+        System.out.println("Test");
+    }
+
+    /**
+     * 默认哨兵，触动规则无异常处理
+     * @param name name
+     * @return String
+     */
+    @SentinelResource(value = "sayHello")
+    public String sayHello(String name) {
+        return "Hello, " + name;
+    }
+
+    /**
+     * 原始函数
+     * 需要借助于本类方法 exceptionHandler、helloFallback 来使用
+     * @param s s
+     * @return String
+     */
+    @SentinelResource(value = "hello", blockHandler = "exceptionHandler", fallback = "helloFallback")
+    public String hello(long s) {
+        return String.format("Hello at %d", s);
+    }
+
+    /**
+     * Fallback 函数，函数签名与原函数一致或加一个 Throwable 类型的参数.
+     * @param s s
+     * @return String
+     */
+    public String helloFallback(long s) {
+        return String.format("Halooooo %d", s);
+    }
+
+    /**
+     * Block 异常处理函数，参数最后多一个 BlockException，其余与原函数一致.
+     * @param s s
+     * @param ex ex
+     * @return String
+     */
+    public String exceptionHandler(long s, BlockException ex) {
+        // Do some log here.
+        ex.printStackTrace();
+        return "Oops, error occurred at " + s;
+    }
+}

sentinel-sample/src/main/java/com/example/demo/util/ExceptionUtil.java

@@ -0,0 +1,20 @@
+package com.example.demo.util;
+
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+
+/**
+ * 异常处理工具类
+ *
+ * @author yclimb
+ * @date 2020/10/12
+ */
+public final class ExceptionUtil {
+
+    /**
+     * 使用 @SentinelResource(blockHandlerClass) 时使用，返回值必须和方法返回值一致
+     * @param ex ex
+     */
+    public static void handleException(BlockException ex) {
+        System.out.println("Oops: " + ex.getClass().getCanonicalName());
+    }
+}

sentinel-sample/src/main/resources/application.properties

@@ -12,8 +12,9 @@ server.port=8080
 # spring 静态资源扫描路径
 spring.resources.static_locations=classpath:/static/
 
+# PS：哨兵控制台需要自己实现，可以使用 docker，地址: https://hub.docker.com/r/bladex/sentinel-dashboard
 # Sentinel 控制台地址
-spring.cloud.sentinel.transport.dashboard=localhost:8080
+spring.cloud.sentinel.transport.dashboard=localhost:8858
 # 取消Sentinel控制台懒加载
 # 默认情况下 Sentinel 会在客户端首次调用的时候进行初始化，开始向控制台发送心跳包
 # 配置 sentinel.eager=true 时，取消Sentinel控制台懒加载功能