Java API invocation flexibility (#18078)

* add direct invocation methods for java (httpclient)

* add direct invocation methods for java (resttemplate)

* handle methods only if endpoints exist for api client

* preserve previous newline to minimize changes

* update httpclient/resttemplate samples

* add common methods in base class

* regenerate samples with base class

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java

@@ -569,6 +569,10 @@ public void processOpts() {
             supportingFiles.add(new SupportingFile("auth/Authentication.mustache", authFolder, "Authentication.java"));
         }
 
+        if (APACHE.equals(getLibrary()) || RESTTEMPLATE.equals(getLibrary())) {
+            supportingFiles.add(new SupportingFile("BaseApi.mustache", invokerFolder, "BaseApi.java"));
+        }
+
         if (FEIGN.equals(getLibrary())) {
             if (getSerializationLibrary() == null) {
                 LOGGER.info("No serializationLibrary configured, using '{}' as fallback", SERIALIZATION_LIBRARY_JACKSON);

modules/openapi-generator/src/main/resources/Java/libraries/apache-httpclient/ApiClient.mustache

@@ -916,15 +916,11 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
   }
 
   /**
-   * Build full URL by concatenating base path, the given sub path and query parameters.
+   * Returns the URL of the client as defined by the server (if exists) or the base path.
    *
-   * @param path The sub path
-   * @param queryParams The query parameters
-   * @param collectionQueryParams The collection query parameters
-   * @param urlQueryDeepObject URL query string of the deep object parameters
-   * @return The full URL
+   * @return The URL for the client.
    */
-  private String buildUrl(String path, List<Pair> queryParams, List<Pair> collectionQueryParams, String urlQueryDeepObject) {
+  public String getBaseURL() {
     String baseURL;
     if (serverIndex != null) {
       if (serverIndex < 0 || serverIndex >= servers.size()) {
@@ -936,6 +932,20 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
     } else {
       baseURL = basePath;
     }
+    return baseURL;
+  }
+
+  /**
+   * Build full URL by concatenating base URL, the given sub path and query parameters.
+   *
+   * @param path The sub path
+   * @param queryParams The query parameters
+   * @param collectionQueryParams The collection query parameters
+   * @param urlQueryDeepObject URL query string of the deep object parameters
+   * @return The full URL
+   */
+  private String buildUrl(String path, List<Pair> queryParams, List<Pair> collectionQueryParams, String urlQueryDeepObject) {
+    String baseURL = getBaseURL();
 
     final StringBuilder url = new StringBuilder();
     url.append(baseURL).append(path);

modules/openapi-generator/src/main/resources/Java/libraries/apache-httpclient/BaseApi.mustache

@@ -0,0 +1,110 @@
+{{>licenseInfo}}
+package {{invokerPackage}};
+
+import com.fasterxml.jackson.core.type.TypeReference;
+
+import java.util.Collections;
+import java.util.Map;
+
+{{>generatedAnnotation}}
+public abstract class BaseApi {
+
+  protected ApiClient apiClient;
+
+  public BaseApi() {
+    this(Configuration.getDefaultApiClient());
+  }
+
+  public BaseApi(ApiClient apiClient) {
+    this.apiClient = apiClient;
+  }
+
+  public ApiClient getApiClient() {
+    return apiClient;
+  }
+
+  public void setApiClient(ApiClient apiClient) {
+    this.apiClient = apiClient;
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @throws ApiException if fails to make API call.
+   */
+  public void invokeAPI(String url, String method) throws ApiException {
+    invokeAPI(url, method, null, null, Collections.emptyMap());
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param additionalHeaders Additional headers for the request.
+   * @throws ApiException if fails to make API call.
+   */
+  public void invokeAPI(String url, String method, Map<String, String> additionalHeaders) throws ApiException {
+    invokeAPI(url, method, null, null, additionalHeaders);
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param request The request object.
+   * @throws ApiException if fails to make API call.
+   */
+  public void invokeAPI(String url, String method, Object request) throws ApiException {
+    invokeAPI(url, method, request, null, Collections.emptyMap());
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param request The request object.
+   * @param additionalHeaders Additional headers for the request.
+   * @throws ApiException if fails to make API call.
+   */
+  public void invokeAPI(String url, String method, Object request, Map<String, String> additionalHeaders) throws ApiException {
+    invokeAPI(url, method, request, null, additionalHeaders);
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param returnType The return type.
+   * @return The API response in the specified type.
+   * @throws ApiException if fails to make API call.
+   */
+  public <T> T invokeAPI(String url, String method, TypeReference<T> returnType) throws ApiException {
+    return invokeAPI(url, method, null, returnType, Collections.emptyMap());
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param request The request object.
+   * @param returnType The return type.
+   * @return The API response in the specified type.
+   * @throws ApiException if fails to make API call.
+   */
+  public <T> T invokeAPI(String url, String method, Object request, TypeReference<T> returnType) throws ApiException {
+    return invokeAPI(url, method, request, returnType, Collections.emptyMap());
+  }
+
+  /**
+   * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+   * @param url The URL for the request, either full URL or only the path.
+   * @param method The HTTP method for the request.
+   * @param request The request object.
+   * @param returnType The return type.
+   * @param additionalHeaders Additional headers for the request.
+   * @return The API response in the specified type.
+   * @throws ApiException if fails to make API call.
+   */
+  public abstract <T> T invokeAPI(String url, String method, Object request, TypeReference<T> returnType, Map<String, String> additionalHeaders) throws ApiException;
+}

modules/openapi-generator/src/main/resources/Java/libraries/apache-httpclient/api.mustache

@@ -5,6 +5,7 @@ import com.fasterxml.jackson.core.type.TypeReference;
 
 import {{invokerPackage}}.ApiException;
 import {{invokerPackage}}.ApiClient;
+import {{invokerPackage}}.BaseApi;
 import {{invokerPackage}}.Configuration;
 {{#models.0}}
 import {{modelPackage}}.*;
@@ -24,25 +25,14 @@ import java.util.StringJoiner;
 
 {{>generatedAnnotation}}
 {{#operations}}
-public class {{classname}} {
-
-
-  private ApiClient apiClient;
+public class {{classname}} extends BaseApi {
 
   public {{classname}}() {
-    this(Configuration.getDefaultApiClient());
+    super(Configuration.getDefaultApiClient());
   }
 
   public {{classname}}(ApiClient apiClient) {
-    this.apiClient = apiClient;
-  }
-
-  public ApiClient getApiClient() {
-    return apiClient;
-  }
-
-  public void setApiClient(ApiClient apiClient) {
-    this.apiClient = apiClient;
+    super(apiClient);
   }
 
   {{#operation}}
@@ -201,6 +191,48 @@ public class {{classname}} {
     );
   }
 
+  {{#-last}}
+  @Override
+  public <T> T invokeAPI(String url, String method, Object request, TypeReference<T> returnType, Map<String, String> additionalHeaders) throws ApiException {
+    String localVarPath = url.replace(apiClient.getBaseURL(), "");
+    StringJoiner localVarQueryStringJoiner = new StringJoiner("&");
+    List<Pair> localVarQueryParams = new ArrayList<Pair>();
+    List<Pair> localVarCollectionQueryParams = new ArrayList<Pair>();
+    Map<String, String> localVarHeaderParams = new HashMap<String, String>();
+    Map<String, String> localVarCookieParams = new HashMap<String, String>();
+    Map<String, Object> localVarFormParams = new HashMap<String, Object>();
+
+    localVarHeaderParams.putAll(additionalHeaders);
+
+    final String[] localVarAccepts = {
+      {{#produces}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/produces}}
+    };
+    final String localVarAccept = apiClient.selectHeaderAccept(localVarAccepts);
+
+    final String[] localVarContentTypes = {
+      {{#consumes}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/consumes}}
+    };
+    final String localVarContentType = apiClient.selectHeaderContentType(localVarContentTypes);
+
+    String[] localVarAuthNames = new String[] { {{#authMethods}}"{{name}}"{{^-last}}, {{/-last}}{{/authMethods}} };
+
+    return apiClient.invokeAPI(
+      localVarPath,
+        method,
+        localVarQueryParams,
+        localVarCollectionQueryParams,
+        localVarQueryStringJoiner.toString(),
+        request,
+        localVarHeaderParams,
+        localVarCookieParams,
+        localVarFormParams,
+        localVarAccept,
+        localVarContentType,
+        localVarAuthNames,
+        returnType
+    );
+  }
+  {{/-last}}
   {{/operation}}
 }
 {{/operations}}

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/BaseApi.mustache

@@ -0,0 +1,74 @@
+package {{invokerPackage}};
+
+import org.springframework.web.client.RestClientException;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.ResponseEntity;
+
+{{>generatedAnnotation}}
+public abstract class BaseApi {
+
+    protected ApiClient apiClient;
+
+    public BaseApi() {
+        this(new ApiClient());
+    }
+
+    public BaseApi(ApiClient apiClient) {
+        this.apiClient = apiClient;
+    }
+
+    public ApiClient getApiClient() {
+        return apiClient;
+    }
+
+    public void setApiClient(ApiClient apiClient) {
+        this.apiClient = apiClient;
+    }
+
+    /**
+     * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+     * @param url The URL for the request, either full URL or only the path.
+     * @param method The HTTP method for the request.
+     * @return ResponseEntity<Void>
+     * @throws RestClientException if an error occurs while attempting to invoke the API
+     */
+    public ResponseEntity<Void> invokeAPI(String url, HttpMethod method) throws RestClientException {
+        return invokeAPI(url, method, null, new ParameterizedTypeReference<Void>() {});
+    }
+
+    /**
+     * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+     * @param url The URL for the request, either full URL or only the path.
+     * @param method The HTTP method for the request.
+     * @param request The request object.
+     * @return ResponseEntity&lt;Void&gt;
+     * @throws RestClientException if an error occurs while attempting to invoke the API
+     */
+    public ResponseEntity<Void> invokeAPI(String url, HttpMethod method, Object request) throws RestClientException {
+        return invokeAPI(url, method, request, new ParameterizedTypeReference<Void>() {});
+    }
+
+    /**
+     * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+     * @param url The URL for the request, either full URL or only the path.
+     * @param method The HTTP method for the request.
+     * @param returnType The return type.
+     * @return ResponseEntity in the specified type.
+     * @throws RestClientException if an error occurs while attempting to invoke the API
+     */
+    public <T> ResponseEntity<T> invokeAPI(String url, HttpMethod method, ParameterizedTypeReference<T> returnType) throws RestClientException {
+        return invokeAPI(url, method, null, returnType);
+    }
+
+    /**
+     * Directly invoke the API for the given URL. Useful if the API returns direct links/URLs for subsequent requests.
+     * @param url The URL for the request, either full URL or only the path.
+     * @param method The HTTP method for the request.
+     * @param request The request object.
+     * @param returnType The return type.
+     * @return ResponseEntity in the specified type.
+     * @throws RestClientException if an error occurs while attempting to invoke the API
+     */
+    public abstract <T> ResponseEntity<T> invokeAPI(String url, HttpMethod method, Object request, ParameterizedTypeReference<T> returnType) throws RestClientException;
+}

modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/api.mustache

@@ -1,6 +1,7 @@
 package {{package}};
 
 import {{invokerPackage}}.ApiClient;
+import {{invokerPackage}}.BaseApi;
 
 {{#imports}}import {{import}};
 {{/imports}}
@@ -31,26 +32,17 @@ import org.springframework.http.ResponseEntity;
 @Component("{{package}}.{{classname}}")
 {{/generateClientAsBean}}
 {{#operations}}
-public class {{classname}} {
-    private ApiClient apiClient;
+public class {{classname}} extends BaseApi {
 
     public {{classname}}() {
-        this(new ApiClient());
+        super(new ApiClient());
     }
 
     {{#generateClientAsBean}}
     @Autowired
     {{/generateClientAsBean}}
     public {{classname}}(ApiClient apiClient) {
-        this.apiClient = apiClient;
-    }
-
-    public ApiClient getApiClient() {
-        return apiClient;
-    }
-
-    public void setApiClient(ApiClient apiClient) {
-        this.apiClient = apiClient;
+        super(apiClient);
     }
 
     {{#operation}}
@@ -159,6 +151,33 @@ public class {{classname}} {
         {{#returnType}}ParameterizedTypeReference<{{#returnType}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{.}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{.}}}{{/isResponseFile}}{{/returnType}}> localReturnType = new ParameterizedTypeReference<{{#returnType}}{{#isResponseFile}}{{#useAbstractionForFiles}}org.springframework.core.io.Resource{{/useAbstractionForFiles}}{{^useAbstractionForFiles}}{{{.}}}{{/useAbstractionForFiles}}{{/isResponseFile}}{{^isResponseFile}}{{{.}}}{{/isResponseFile}}{{/returnType}}>() {};{{/returnType}}{{^returnType}}ParameterizedTypeReference<Void> localReturnType = new ParameterizedTypeReference<Void>() {};{{/returnType}}
         return apiClient.invokeAPI("{{{path}}}", HttpMethod.{{httpMethod}}, {{#hasPathParams}}uriVariables{{/hasPathParams}}{{^hasPathParams}}Collections.<String, Object>emptyMap(){{/hasPathParams}}, localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, localReturnType);
     }
+    {{#-last}}
+
+    @Override
+    public <T> ResponseEntity<T> invokeAPI(String url, HttpMethod method, Object request, ParameterizedTypeReference<T> returnType) throws RestClientException {
+        String localVarPath = url.replace(apiClient.getBasePath(), "");
+        Object localVarPostBody = request;
+
+        final Map<String, Object> uriVariables = new HashMap<String, Object>();
+        final MultiValueMap<String, String> localVarQueryParams = new LinkedMultiValueMap<String, String>();
+        final HttpHeaders localVarHeaderParams = new HttpHeaders();
+        final MultiValueMap<String, String> localVarCookieParams = new LinkedMultiValueMap<String, String>();
+        final MultiValueMap<String, Object> localVarFormParams = new LinkedMultiValueMap<String, Object>();
+
+        final String[] localVarAccepts = { {{#hasProduces}}
+            {{#produces}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/produces}}
+        {{/hasProduces}} };
+        final List<MediaType> localVarAccept = apiClient.selectHeaderAccept(localVarAccepts);
+        final String[] localVarContentTypes = { {{#hasConsumes}}
+            {{#consumes}}"{{{mediaType}}}"{{^-last}}, {{/-last}}{{/consumes}}
+        {{/hasConsumes}} };
+        final MediaType localVarContentType = apiClient.selectHeaderContentType(localVarContentTypes);
+
+        String[] localVarAuthNames = new String[] { {{#authMethods}}"{{name}}"{{^-last}}, {{/-last}}{{/authMethods}} };
+
+        return apiClient.invokeAPI(localVarPath, method, uriVariables, localVarQueryParams, localVarPostBody, localVarHeaderParams, localVarCookieParams, localVarFormParams, localVarAccept, localVarContentType, localVarAuthNames, returnType);
+    }
+    {{/-last}}
     {{/operation}}
 }
 {{/operations}}