Sentinel Apache Httpclient 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-apache-httpclient-adapter</artifactId>
    <version>x.y.z</version>
</dependency>

We can use the SentinelApacheHttpClientBuilder when CloseableHttpClient at initialization, for example:

CloseableHttpClient httpclient = new SentinelApacheHttpClientBuilder().build();

If we want to add some additional configurations, we can refer to the following code

HttpClientBuilder builder = new SentinelApacheHttpClientBuilder();
//builder Other Definitions
CloseableHttpClient httpclient = builder.build();

Configuration

• SentinelApacheHttpClientConfig configuration:

|name|description|type|default value||------|------------|------|-------||prefix|customize resource prefix|String|httpclient:||extractor|customize resource extractor|ApacheHttpClientResourceExtractor|DefaultApacheHttpClientResourceExtractor||fallback|handle request when it is blocked|ApacheHttpClientFallback|DefaultApacheHttpClientFallback|

extractor (resource extractor)

We can define ApacheHttpClientResourceExtractor to customize resource extractor replace DefaultApacheHttpClientResourceExtractor at SentinelApacheHttpClientBuilder default config, for example: httpclient:GET:/httpclient/back/1 ==> httpclient:GET:/httpclient/back/{id}

SentinelApacheHttpClientConfig config = new SentinelApacheHttpClientConfig();
config.setExtractor(new ApacheHttpClientResourceExtractor() {

    @Override
    public String extractor(HttpRequestWrapper request) {
        String contains = "/httpclient/back/";
        String uri = request.getRequestLine().getUri();
        if (uri.startsWith(contains)) {
            uri = uri.substring(0, uri.indexOf(contains) + contains.length()) + "{id}";
        }
        return request.getMethod() + ":" + uri;
    }
});
CloseableHttpClient httpclient = new SentinelApacheHttpClientBuilder(config).build();

fallback (Block handling)

We can define ApacheHttpClientFallback at SentinelApacheHttpClientBuilder default config, to handle request is blocked according to the actual scenario, for example:

public class DefaultApacheHttpClientFallback implements ApacheHttpClientFallback {

    @Override
    public CloseableHttpResponse handle(HttpRequestWrapper request, BlockException e) {
        // Just wrap and throw the exception.
        throw new SentinelRpcException(e);
    }
}