流量控制服务降级神器之Sentinel

java -Dserver.port=9999 -Dcsp.sentinel.dashboard.server=localhost:9999 -Dproject.name=sentinel-dashboard -jar sentinel-dashboard-1.8.6.jar

<dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        </dependency>

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-actuator</artifactId>
      <version>2.4.2</version>
      <scope>compile</scope>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-actuator-autoconfigure</artifactId>
      <version>2.4.2</version>
      <scope>compile</scope>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-configuration-processor</artifactId>
      <version>2.4.2</version>
      <scope>compile</scope>
      <optional>true</optional>
    </dependency>

spring:
  application:
    name: xxxxx
  cloud:
    nacos:
      config:
        username: nacos
        password: nacos
        context-path: /nacos
        server-addr: 127.0.0.1:8848
        file-extension: yml
        group: DEFAULT_GROUP
      discovery:
        username: nacos
        password: nacos
        server-addr: 127.0.0.1:8848
    sentinel:
      # sentinel看板的地址
      transport:
        dashboard: localhost:9999
      # 开启对sentinel看板的饥饿式加载。sentinel默认是懒加载机制，只有访问过一次的资源才会被监控，通过关闭懒加载，在项目启动时就连接sentinel控制台
      eager: true

package com.alibaba.csp.sentinel.annotation;

import com.alibaba.csp.sentinel.EntryType;

import java.lang.annotation.*;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface SentinelResource {

    /**
     * @return name of the Sentinel resource
     */
    String value() default "";

    /**
     * @return the entry type (inbound or outbound), outbound by default
     */
    EntryType entryType() default EntryType.OUT;

    /**
     * @return the classification (type) of the resource
     * @since 1.7.0
     */
    int resourceType() default 0;

    /**
     * @return name of the block exception function, empty by default
     */
    String blockHandler() default "";

    /**
     * The {@code blockHandler} is located in the same class with the original method by default.
     * However, if some methods share the same signature and intend to set the same block handler,
     * then users can set the class where the block handler exists. Note that the block handler method
     * must be static.
     *
     * @return the class where the block handler exists, should not provide more than one classes
     */
    Class<?>[] blockHandlerClass() default {};

    /**
     * @return name of the fallback function, empty by default
     */
    String fallback() default "";

    /**
     * The {@code defaultFallback} is used as the default universal fallback method.
     * It should not accept any parameters, and the return type should be compatible
     * with the original method.
     *
     * @return name of the default fallback method, empty by default
     * @since 1.6.0
     */
    String defaultFallback() default "";

    /**
     * The {@code fallback} is located in the same class with the original method by default.
     * However, if some methods share the same signature and intend to set the same fallback,
     * then users can set the class where the fallback function exists. Note that the shared fallback method
     * must be static.
     *
     * @return the class where the fallback method is located (only single class)
     * @since 1.6.0
     */
    Class<?>[] fallbackClass() default {};

    /**
     * @return the list of exception classes to trace, {@link Throwable} by default
     * @since 1.5.1
     */
    Class<? extends Throwable>[] exceptionsToTrace() default {Throwable.class};
    
    /**
     * Indicates the exceptions to be ignored. Note that {@code exceptionsToTrace} should
     * not appear with {@code exceptionsToIgnore} at the same time, or {@code exceptionsToIgnore}
     * will be of higher precedence.
     *
     * @return the list of exception classes to ignore, empty by default
     * @since 1.6.0
     */
    Class<? extends Throwable>[] exceptionsToIgnore() default {};
}