Skip Manual Controllers: Auto‑Generate SpringBoot APIs with Lego‑Starter

1. Overview

In daily development, writing Controllers is tedious. Many companies enforce that Controllers contain no business logic, only parameter parsing and result conversion. However, source code often contains unwanted logic. This article proposes eliminating Controllers entirely by exposing CommandService and QueryService directly as web endpoints.

1.1 Background

By encapsulating CommandService and QueryService as application services, we can expose capabilities via Controllers, which is repetitive and low‑value work. The strategy is to let the framework handle this repetition.

1.2 Goal

Goal: avoid writing Controller code while preserving the same functionality, and integrate with Swagger for dynamic API documentation.

Expose CommandService and QueryService as web interfaces without manual Controllers.

Integrate with Swagger to generate API docs automatically.

2. Quick Start

2.1 Environment Preparation

Add the lego-starter dependency to your pom.xml:

<dependency>
    <groupId>com.geekhalo.lego</groupId>
    <artifactId>lego-starter</artifactId>
    <version>0.1.11-rest-SNAPSHOT</version>
</dependency>

Add Swagger dependencies:

<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-boot-starter</artifactId>
    <version>3.0.0</version>
</dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-data-rest</artifactId>
    <version>3.0.0</version>
</dependency>

Create a Swagger configuration class:

@Configuration
@EnableSwagger2
public class SpringFoxConfiguration {
}

2.2 First Unified Controller

After starting the application, open http://127.0.0.1:8080/swagger-ui/. Two auto‑generated Controllers appear: command-dispatcher-controller (exposes CommandService) and query-dispatcher-controller (exposes QueryService). Both support RequestBody (JSON) and RequestParam (simple parameters). The Query controller additionally supports HTTP GET.

2.3 Command Controller

Annotate a CommandService interface with @AutoRegisterWebController(name="order") to expose its methods:

@CommandServiceDefinition(domainClass = Order.class, idClass = Long.class, repositoryClass = OrderRepository.class)
@AutoRegisterWebController(name = "order")
public interface OrderCommandService {
    void cancel(Long orderId);
    Long create(CreateOrderCommand command);
    void paySuccess(PaySuccessCommand command);
}

The Swagger UI now shows endpoints for cancel, create, and paySuccess with the same signatures as manually written Controllers.

2.4 Query Controller

Similarly, annotate a QueryService:

@QueryServiceDefinition(domainClass = Order.class, repositoryClass = OrderQueryRepository.class)
@Validated
@AutoRegisterWebController(name = "order")
public interface OrderQueryService {
    OrderDetail getById(@Valid @NotNull(message = "订单号不能为null") Long id);
    Page<OrderDetail> pageByUserId(@Valid @NotNull(message = "查询参数不能为 null") PageByUserId query);
    List<OrderDetail> getByUserId(@Valid @NotNull(message = "查询参数不能为 null") GetByUserId getByUserId);
    Long countByUser(@Valid @NotNull(message = "查询参数不能为 null") CountByUserId countByUserId);
    List<OrderDetail> getPaidByUserId(Long id);
}

The generated Query controller mirrors the service methods, providing clear request and response structures.

3. Design & Extension

3.1 Unified Controller

The QueryDispatcherController acts as a universal entry point for all query requests. Initialization registers all QueryService beans into a QueryServicesRegistry, which then populates a QueryMethodRegistry. At runtime, the dispatcher looks up the appropriate method by serviceName and methodName and invokes it.

3.2 Swagger Integration

The QueryServicesProvider extracts method metadata from QueryMethodRegistry, creates request handlers, and registers them with Swagger, enabling dynamic API documentation.