sentinel 资源定义方式

主流框架的适配

1. dubbo

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-dubbo-adapter</artifactId>
    <version>x.y.z</version>
</dependency>

2. Web端适配

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-web-servlet</artifactId>
    <version>x.y.z</version>
</dependency>

在servlet层原生整合(拦截所有请求),如果想自定义拦截配置,可以有下面2种不同方式

• springboot项目

@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean sentinelFilterRegistration() {
        FilterRegistrationBean<Filter> registration = new FilterRegistrationBean<>();
        registration.setFilter(new CommonFilter());
        registration.addUrlPatterns("/*");
        registration.setName("sentinelFilter");
        registration.setOrder(1);
        return registration;
    }
}

• xml项目

<filter>
	<filter-name>SentinelCommonFilter</filter-name>
	<filter-class>com.alibaba.csp.sentinel.adapter.servlet.CommonFilter</filter-class>
</filter>

<filter-mapping>
	<filter-name>SentinelCommonFilter</filter-name>
	<url-pattern>/*</url-pattern>
</filter-mapping>

3. GRPC

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-grpc-adapter</artifactId>
    <version>x.y.z</version>
</dependency>

client 端代码如下

public class ServiceClient {

    private final ManagedChannel channel;

    ServiceClient(String host, int port) {
        this.channel = ManagedChannelBuilder.forAddress(host, port)
            .intercept(new SentinelGrpcClientInterceptor()) // 在此处注册拦截器
            .build();
        // 在此处初始化客户端 stub 类
    }
}

4. ApiGateway

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-spring-cloud-gateway-adapter</artifactId>
    <version>x.y.z</version>
</dependency>

使用的代码

@Configuration
public class GatewayConfiguration {

    private final List<ViewResolver> viewResolvers;
    private final ServerCodecConfigurer serverCodecConfigurer;

    public GatewayConfiguration(ObjectProvider<List<ViewResolver>> viewResolversProvider,
                                ServerCodecConfigurer serverCodecConfigurer) {
        this.viewResolvers = viewResolversProvider.getIfAvailable(Collections::emptyList);
        this.serverCodecConfigurer = serverCodecConfigurer;
    }

    @Bean
    @Order(Ordered.HIGHEST_PRECEDENCE)
    public SentinelGatewayBlockExceptionHandler sentinelGatewayBlockExceptionHandler() {
        // Register the block exception handler for Spring Cloud Gateway.
        return new SentinelGatewayBlockExceptionHandler(viewResolvers, serverCodecConfigurer);
    }

    @Bean
    @Order(-1)
    public GlobalFilter sentinelGatewayFilter() {
        return new SentinelGatewayFilter();
    }
}

抛出异常的方式定义资源

public static void main(String[] args) {
    // 配置规则.
    initFlowRules();

    while (true) {
        // 1.5.0 版本开始可以直接利用 try-with-resources 特性
        try (Entry entry = SphU.entry("HelloWorld")) {
            // 被保护的逻辑
            System.out.println("hello world");
	} catch (BlockException ex) {
            // 处理被流控的逻辑
	    System.out.println("blocked!");
	}
    }
}

返回布尔值方式定义资源

  // 资源名可使用任意有业务语义的字符串
  if (SphO.entry("自定义资源名")) {
    // 务必保证finally会被执行
    try {
      /**
      * 被保护的业务逻辑
      */
    } finally {
      SphO.exit();
    }
  } else {
    // 资源访问阻止，被限流或被降级
    // 进行相应的处理操作
  }

异步调用支持

try {
    AsyncEntry entry = SphU.asyncEntry(resourceName);

    // 异步调用.
    doAsync(userId, result -> {
        try {
            // 在此处处理异步调用的结果.
        } finally {
            // 在回调结束后 exit.
            entry.exit();
        }
    });
} catch (BlockException ex) {
    // Request blocked.
    // Handle the exception (e.g. retry or fallback).
}

注解

@SentinelResource("HelloWorld")
public void helloWorld() {
    // 资源中的逻辑
    System.out.println("hello world");
}