如何用openapi-generator/swagger-codegen-maven-plugin生成纯Kotlin Spring客户端代码

以下是使用openapi-generator-maven-plugin生成纯Kotlin、支持Spring自动注入的客户端方案，无需混用Java代码：

一、RestTemplate风格自动注入客户端 #

1. Maven插件配置 #

指定kotlin语言和spring库，开启Spring组件注解与RestTemplate支持：

<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>6.6.0</version>
    <executions>
        <execution>
            <id>kotlin-rest-client</id>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${project.basedir}/src/main/resources/openapi.yaml</inputSpec>
                <generatorName>kotlin</generatorName>
                <library>spring</library>
                <output>${project.build.directory}/generated-sources/openapi-rest</output>
                <apiPackage>com.yourteam.api.client</apiPackage>
                <modelPackage>com.yourteam.api.model</modelPackage>
                <configOptions>
                    <component>true</component>
                    <restTemplate>true</restTemplate>
                    <kotlinNullable>true</kotlinNullable>
                    <useSpringBoot3>true</useSpringBoot3>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

2. 直接使用 #

生成的客户端类自带@Component注解，可直接通过@Autowired注入：

@Service
class OrderService {
    @Autowired
    private lateinit var productApiClient: ProductApiClient

    fun getProductDetail(id: Long): Product {
        return productApiClient.getProductById(id)
    }
}

二、Feign风格自动注入客户端 #

1. Maven插件配置 #

指定feign库，启用Spring Cloud Feign支持：

<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>6.6.0</version>
    <executions>
        <execution>
            <id>kotlin-feign-client</id>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${project.basedir}/src/main/resources/openapi.yaml</inputSpec>
                <generatorName>kotlin</generatorName>
                <library>feign</library>
                <output>${project.build.directory}/generated-sources/openapi-feign</output>
                <apiPackage>com.yourteam.feign.client</apiPackage>
                <modelPackage>com.yourteam.feign.model</modelPackage>
                <configOptions>
                    <useSpringCloudFeign>true</useSpringCloudFeign>
                    <component>true</component>
                    <kotlinNullable>true</kotlinNullable>
                    <springBoot3>true</springBoot3>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

2. 补充依赖与配置 #

添加Spring Cloud Feign依赖：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

在Spring启动类上开启Feign扫描：

@SpringBootApplication
@EnableFeignClients(basePackages = ["com.yourteam.feign.client"])
class Application

3. 直接使用 #

生成的Feign接口自带@FeignClient注解，直接注入调用：

@Service
class PaymentService {
    @Autowired
    private lateinit var paymentFeignClient: PaymentFeignApi

    fun createPayment(orderId: Long): PaymentResult {
        return paymentFeignClient.initPayment(orderId)
    }
}

注意事项 #

• 确保OpenAPI Spec为3.x版本，openapi-generator对其兼容性更好
• 插件版本优先选择最新稳定版，避免Kotlin语法兼容问题
• 若需自定义RestTemplate/Feign配置，直接在Spring容器中声明对应Bean即可，生成的客户端会自动复用

内容的提问来源于stack exchange，提问作者drugzverya