sl-express/sentinel/sentinel-adapter/sentinel-okhttp-adapter/README.md

Sentinel OkHttp Adapter

Introduction

Sentinel provides integration for OkHttp client to enable flow control for web requests.

Add the following dependency in pom.xml (if you are using Maven):

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

We can add the SentinelOkHttpInterceptor interceptor when OkHttpClient at initialization, for example:

OkHttpClient client = new OkHttpClient.Builder()
        .addInterceptor(new SentinelOkHttpInterceptor(new SentinelOkHttpConfig()))
        .build();

Configuration

SentinelOkHttpConfig configuration:

name	description	type	default value
resourcePrefix	customized resource name prefix	String	okhttp:
resourceExtractor	customized resource extractor	OkHttpResourceExtractor	DefaultOkHttpResourceExtractor
fallback	handle request when it is blocked	OkHttpFallback	DefaultOkHttpFallback

Resource Extractor

We can define OkHttpResourceExtractor to customize the logic of extracting resource name from the HTTP request. For example: okhttp:GET:ip:port/okhttp/back/1 ==> /okhttp/back/{id}

OkHttpResourceExtractor extractor = (request, connection) -> {
    String resource = request.url().toString();
    String regex = "/okhttp/back/";
    if (resource.contains(regex)) {
        resource = resource.substring(0, resource.indexOf(regex) + regex.length()) + "{id}";
    }
    return resource;
};

The pattern of default resource name extractor is ${HTTP_METHOD}:${URL} (e.g. GET:/foo).

Fallback (Block handling)

We can define OkHttpFallback to handle blocked request. For example:

public class DefaultOkHttpFallback implements OkHttpFallback {

    @Override
    public Response handle(Request request, Connection connection, BlockException e) {
        return new Response(myErrorBuilder);
    }
}