sl-express/sentinel/sentinel-adapter/sentinel-okhttp-adapter/README.md
shuhongfan cf5ac25c14 init
2023-09-04 16:40:17 +08:00

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# 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):
```xml
<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:
```java
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}`
```java
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:
```java
public class DefaultOkHttpFallback implements OkHttpFallback {
@Override
public Response handle(Request request, Connection connection, BlockException e) {
return new Response(myErrorBuilder);
}
}
```