Netflix/feign
Feign
Feign is a declarative Java HTTP client that automates the generation of web service clients. It allows developers to define REST API endpoints using interfaces and annotations, removing the need to write manual request and response boilerplate code.
The project uses dynamic proxies to map method calls to HTTP request templates. It features a pluggable pipeline of encoders and decoders to transform Java objects into request bodies and convert response bodies back into type-safe objects.
The library covers a broad range of integration capabilities, including request interception for header management, strategy-based retry logic for resilient service consumption, and template expansion for URIs. It also provides tools for recording HTTP traffic logs and gathering client performance metrics.
Features
- Declarative API Clients - Allows the definition of network endpoints using a declarative interface style with annotations.
- Pluggable Transformation Pipelines - Provides a pluggable pipeline of interchangeable encoders and decoders for transforming network payloads.
- API Request Automation - Automates the transformation of Java objects into formatted HTTP request bodies and query parameters.
- API Client Generators - Automates the generation of HTTP client implementations by mapping Java method calls to request templates.
- Microservices Communications - Standardizes synchronous communication between distributed microservices using a declarative client approach.
- HTTP Client Libraries - Serves as a comprehensive Java library for performing synchronous and asynchronous HTTP requests.
- HTTP Client Wrappers - Wraps complex HTTP communication into type-safe Java interfaces to eliminate request boilerplate.
- Client Services - Implements network clients that provide type-safe responses and automated request handling.
- Response Body Decoders - Transforms HTTP response payloads into type-safe Java objects using a pluggable decoding system.
- Dynamic Proxies - Uses runtime dynamic proxies to intercept interface calls and dispatch them as HTTP requests.
- Interface-to-Endpoint Mappings - Maps Java method signatures and annotations directly to HTTP endpoints to automate request construction.
- REST Clients - Implements an interface-based approach to define and execute requests against RESTful APIs.
- Query Parameter Encoders - Automatically formats maps and objects into valid query strings for dynamic request URL construction.
- Multipart Form Encoding - Serializes request payloads into multipart/form-data or url-encoded formats for web service transmission.
- Request Header Configuration - Provides comprehensive tools for defining static and dynamic HTTP request headers via annotations and interceptors.
- Retry Policies - Implements configurable retry policies to automatically re-execute failed network requests based on specific exceptions.
- HTTP Request Interceptors - Includes middleware components to intercept and modify outgoing requests for global header injection and authentication.
- API Error Handling Patterns - Processes non-success HTTP responses through a custom decoder to wrap failures into type-safe exceptions.
- Interceptor Sequences - Processes outgoing requests through an ordered sequence of interceptors to modify metadata or inject headers.
- Retry Strategies - Determines whether to re-execute failed network operations based on configurable policies and exception types.
- Resilience Retry Patterns - Implements configurable retry policies and failure handling to ensure resilient web service consumption.
- URI Template Expanders - Resolves placeholders in URIs and headers using standard template expansion rules and method parameters.
- External API Integrations - Facilitates integration with external REST services using custom interceptors and error handling.
- Request Body Attachers - Converts Java objects into HTTP request bodies using configurable encoders and template expansion.
- REST框架 - 声明式HTTP客户端连接器。
