OpenAPI生成Java客户端时contentType变量重复定义错误

OpenAPI 3.0.1 Schema文件 #

openapi: 3.0.1
info:
  title: tt
  version: 1.0.0
servers:
  - url: https://1.1.1.1
paths:
  /controller/user/login:
    post:
      tags:
        - default
      summary: Login
      requestBody:
        content:
          application/json:
            schema:
              type: object
              example:
                email: user
                password: user
                from: user
      parameters:
        - name: Content-Type
          in: header
          schema:
            type: string
          example: application/json
      responses:
        '200':
          description: Successful response
          content:
            application/json: {}

Maven插件配置 #

<plugin>
    <groupId>org.openapitools</groupId>
    <artifactId>openapi-generator-maven-plugin</artifactId>
    <version>4.3.1</version>
    <executions>
        <execution>
            <id>id1</id>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${project.basedir}/src/main/resources/open-api/schema_1.yaml</inputSpec>
                <generatorName>java</generatorName>
                <library>google-api-client</library>
                <skipValidateSpec>true</skipValidateSpec>
                <output>${codegen.rest.dir}</output>
                <modelPackage>${basepackage}.pkg1</modelPackage>
                <apiPackage>${basepackage}.pkg1.interfaces</apiPackage>
                <invokerPackage>${basepackage}.pkg1.client</invokerPackage>
                <addCompileSourceRoot>false</addCompileSourceRoot>
                <generateSupportingFiles>true</generateSupportingFiles>
                <generateApis>true</generateApis>
                <generateApiDocumentation>false</generateApiDocumentation>
                <generateApiTests>false</generateApiTests>
                <generateModelTests>false</generateModelTests>
                <generateModelDocumentation>false</generateModelDocumentation>
                <configOptions>
                    <java8>true</java8>
                    <library>resttemplate</library>
                    <dateLibrary>java8</dateLibrary>
                    <sourceFolder>.</sourceFolder>
                    <delegatePattern>false</delegatePattern>
                </configOptions>
            </configuration>
        </execution>         
    </executions>
</plugin>

编译错误信息 #

DefaultApi.java:[91,25] variable contentType is already defined in method controllerUserLoginPostWithHttpInfo(java.lang.String,java.lang.Object)

生成代码中的问题 #

生成的DefaultApi.java中，方法参数contentType与方法内局部变量contentType重名：

public ResponseEntity<Void> controllerUserLoginPostWithHttpInfo(String contentType, Object body) throws RestClientException {
        Object postBody = body;
        
        String path = apiClient.expandPath("/controller/user/login", Collections.<String, Object>emptyMap());

        final MultiValueMap<String, String> queryParams = new LinkedMultiValueMap<String, String>();
        final HttpHeaders headerParams = new HttpHeaders();
        final MultiValueMap<String, String> cookieParams = new LinkedMultiValueMap<String, String>();
        final MultiValueMap formParams = new LinkedMultiValueMap();

        if (contentType != null)
        headerParams.add("Content-Type", apiClient.parameterToString(contentType));

        final String[] accepts = { 
            "application/json"
        };
        final List<MediaType> accept = apiClient.selectHeaderAccept(accepts);
        final String[] contentTypes = { 
            "application/json"
        };
        final MediaType contentType = apiClient.selectHeaderContentType(contentTypes);

        String[] authNames = new String[] {  };

        ParameterizedTypeReference<Void> returnType = new ParameterizedTypeReference<Void>() {};
        return apiClient.invokeAPI(path, HttpMethod.POST, queryParams, postBody, headerParams, cookieParams, formParams, accept, contentType, authNames, returnType);
}

已尝试添加<localVarPrefix>localVar</localVarPrefix>配置项，但问题未解决。

解决方案 #

方案1：移除Schema中手动定义的Content-Type header参数 #

你的OpenAPI Schema已经通过requestBody指定了application/json的请求内容类型，OpenAPI Generator会自动处理Content-Type请求头，无需手动在parameters里添加该参数。移除后生成的代码不会出现重名问题：

# 修改后的paths部分
paths:
  /controller/user/login:
    post:
      tags:
        - default
      summary: Login
      requestBody:
        content:
          application/json:
            schema:
              type: object
              example:
                email: user
                password: user
                from: user
      responses:
        '200':
          description: Successful response
          content:
            application/json: {}

方案2：修改自定义Content-Type参数的名称 #

如果业务必须保留自定义的Content-Type头（比如支持非标准内容类型），可以修改参数名称避免冲突，例如改成X-Content-Type：

parameters:
  - name: X-Content-Type
    in: header
    schema:
      type: string
    example: application/json

方案3：升级OpenAPI Generator版本 #

你使用的4.3.1版本较老旧，该变量重名bug在后续版本（如5.x及以上）已修复。升级插件到最新稳定版即可解决问题：

<version>6.6.0</version> <!-- 替换为最新稳定版 -->

方案4：自定义代码模板（进阶） #

若上述方案均不适用，可自定义Java代码模板，修改局部变量contentType的命名。找到OpenAPI Generator的Java模板文件（api.mustache），将局部变量名改为selectedContentType或其他不冲突名称，再通过插件配置指定自定义模板路径。

内容的提问来源于stack exchange，提问作者Peter