[Java] Add streaming endpoint support (#9813)

* add streaming endpoint support to java client

* update doc

docs/generators/java.md

@@ -59,6 +59,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
 |sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
 |sourceFolder|source folder for generated code| |src/main/java|
+|supportStreaming|Support streaming endpoint (beta)| |false|
 |useAbstractionForFiles|Use alternative types instead of java.io.File to allow passing bytes without a file on disk. Available on resttemplate library| |false|
 |useBeanValidation|Use BeanValidation API annotations| |false|
 |useGzipFeature|Send gzip-encoded requests| |false|

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

@@ -63,6 +63,7 @@ public class JavaClientCodegen extends AbstractJavaCodegen
     public static final String MICROPROFILE_FRAMEWORK = "microprofileFramework";
     public static final String USE_ABSTRACTION_FOR_FILES = "useAbstractionForFiles";
     public static final String DYNAMIC_OPERATIONS = "dynamicOperations";
+    public static final String SUPPORT_STREAMING = "supportStreaming";
     public static final String GRADLE_PROPERTIES= "gradleProperties";
 
     public static final String PLAY_24 = "play24";
@@ -112,6 +113,7 @@ public class JavaClientCodegen extends AbstractJavaCodegen
     protected boolean caseInsensitiveResponseHeaders = false;
     protected boolean useAbstractionForFiles = false;
     protected boolean dynamicOperations = false;
+    protected boolean supportStreaming = false;
     protected String gradleProperties;
     protected String authFolder;
     protected String serializationLibrary = null;
@@ -156,6 +158,7 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         cliOptions.add(CliOption.newString(MICROPROFILE_FRAMEWORK, "Framework for microprofile. Possible values \"kumuluzee\""));
         cliOptions.add(CliOption.newBoolean(USE_ABSTRACTION_FOR_FILES, "Use alternative types instead of java.io.File to allow passing bytes without a file on disk. Available on " + RESTTEMPLATE + " library"));
         cliOptions.add(CliOption.newBoolean(DYNAMIC_OPERATIONS, "Generate operations dynamically at runtime from an OAS", this.dynamicOperations));
+        cliOptions.add(CliOption.newBoolean(SUPPORT_STREAMING, "Support streaming endpoint (beta)", this.supportStreaming));
         cliOptions.add(CliOption.newString(GRADLE_PROPERTIES, "Append additional Gradle proeprties to the gradle.properties file"));
 
         supportedLibraries.put(JERSEY1, "HTTP client: Jersey client 1.19.x. JSON processing: Jackson 2.9.x. Enable gzip request encoding using '-DuseGzipFeature=true'. IMPORTANT NOTE: jersey 1.x is no longer actively maintained so please upgrade to 'jersey2' or other HTTP libraries instead.");
@@ -321,6 +324,11 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         }
         additionalProperties.put(DYNAMIC_OPERATIONS, dynamicOperations);
 
+        if (additionalProperties.containsKey(SUPPORT_STREAMING)) {
+            this.setSupportStreaming(Boolean.parseBoolean(additionalProperties.get(SUPPORT_STREAMING).toString()));
+        }
+        additionalProperties.put(SUPPORT_STREAMING, supportStreaming);
+
         if (additionalProperties.containsKey(GRADLE_PROPERTIES)) {
             this.setGradleProperties(additionalProperties.get(GRADLE_PROPERTIES).toString());
         }
@@ -992,6 +1000,10 @@ public class JavaClientCodegen extends AbstractJavaCodegen
         this.dynamicOperations = dynamicOperations;
     }
 
+    public void setSupportStreaming(final boolean supportStreaming) {
+        this.supportStreaming = supportStreaming;
+    }
+
     public void setGradleProperties(final String gradleProperties) {
         this.gradleProperties= gradleProperties;
     }

modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache

@@ -1123,6 +1123,23 @@ public class ApiClient {
         }
     }
 
+    {{#supportStreaming}}
+    public InputStream executeStream(Call call, Type returnType) throws ApiException {
+        try {
+             Response response = call.execute();
+             if (!response.isSuccessful()) {
+                 throw new ApiException(response.code(), response.message());
+             }
+             if (response.body() == null) {
+                 return null;
+             }
+             return response.body().byteStream();
+        } catch (IOException e) {
+            throw new ApiException(e);
+        }
+    }
+
+    {{/supportStreaming}}
     /**
      * {@link #executeAsync(Call, Type, ApiCallback)}
      *

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

@@ -47,6 +47,9 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+{{#supportStreaming}}
+import java.io.InputStream;
+{{/supportStreaming}}
 {{/fullJavaUtil}}
 
 {{#operations}}
@@ -247,10 +250,18 @@ public class {{classname}} {
     {{#isDeprecated}}
     @Deprecated
     {{/isDeprecated}}
+    {{#vendorExtensions.x-streaming}}
+    public {{#returnType}}InputStream {{/returnType}}{{^returnType}}void {{/returnType}}{{operationId}}({{#allParams}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws ApiException {
+        {{#returnType}}InputStream localVarResp = {{/returnType}}{{operationId}}WithHttpInfo({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});{{#returnType}}
+        return localVarResp;{{/returnType}}
+    }
+    {{/vendorExtensions.x-streaming}}
+    {{^vendorExtensions.x-streaming}}
     public {{#returnType}}{{{.}}} {{/returnType}}{{^returnType}}void {{/returnType}}{{operationId}}({{#allParams}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws ApiException {
         {{#returnType}}ApiResponse<{{{.}}}> localVarResp = {{/returnType}}{{operationId}}WithHttpInfo({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});{{#returnType}}
         return localVarResp.getData();{{/returnType}}
     }
+    {{/vendorExtensions.x-streaming}}
     {{/vendorExtensions.x-group-parameters}}
 
     {{^vendorExtensions.x-group-parameters}}/**
@@ -279,11 +290,17 @@ public class {{classname}} {
     {{#isDeprecated}}
     @Deprecated
     {{/isDeprecated}}
-    public{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}private{{/vendorExtensions.x-group-parameters}} ApiResponse<{{{returnType}}}{{^returnType}}Void{{/returnType}}> {{operationId}}WithHttpInfo({{#allParams}}{{#useBeanValidation}}{{>beanValidationQueryParams}}{{/useBeanValidation}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws ApiException {
+    public{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}private{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-streaming}} InputStream {{operationId}}WithHttpInfo({{#allParams}}{{#useBeanValidation}}{{>beanValidationQueryParams}}{{/useBeanValidation}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws ApiException {
+        okhttp3.Call localVarCall = {{operationId}}ValidateBeforeCall({{#allParams}}{{paramName}}, {{/allParams}}null);
+        {{#returnType}}Type localVarReturnType = new TypeToken<{{{returnType}}}>(){}.getType();
+        return localVarApiClient.executeStream(localVarCall, localVarReturnType);{{/returnType}}
+    }
+    {{/vendorExtensions.x-streaming}}{{^vendorExtensions.x-streaming}} ApiResponse<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}Void{{/returnType}}> {{operationId}}WithHttpInfo({{#allParams}}{{#useBeanValidation}}{{>beanValidationQueryParams}}{{/useBeanValidation}}{{{dataType}}} {{paramName}}{{^-last}}, {{/-last}}{{/allParams}}) throws ApiException {
         okhttp3.Call localVarCall = {{operationId}}ValidateBeforeCall({{#allParams}}{{paramName}}, {{/allParams}}null);
         {{#returnType}}Type localVarReturnType = new TypeToken<{{{returnType}}}>(){}.getType();
         return localVarApiClient.execute(localVarCall, localVarReturnType);{{/returnType}}{{^returnType}}return localVarApiClient.execute(localVarCall);{{/returnType}}
     }
+    {{/vendorExtensions.x-streaming}}
 
     {{^vendorExtensions.x-group-parameters}}/**
      * {{summary}} (asynchronously)

modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/api_test.mustache

@@ -13,6 +13,9 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+{{#supportStreaming}}
+import java.io.InputStream;
+{{/supportStreaming}}
 {{/fullJavaUtil}}
 
 /**
@@ -37,10 +40,16 @@ public class {{classname}}Test {
         {{#allParams}}
         {{{dataType}}} {{paramName}} = null;
         {{/allParams}}
-        {{#returnType}}{{{.}}} response = {{/returnType}}api.{{operationId}}{{^vendorExtensions.x-group-parameters}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}({{#requiredParams}}{{paramName}}{{^-last}}, {{/-last}}{{/requiredParams}}){{#optionalParams}}
+        {{#vendorExtensions.x-streaming}}
+                InputStream response = api.{{operationId}}{{^vendorExtensions.x-group-parameters}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}({{#requiredParams}}{{paramName}}{{^-last}}, {{/-last}}{{/requiredParams}}){{#optionalParams}}
                 .{{paramName}}({{paramName}}){{/optionalParams}}
                 .execute();{{/vendorExtensions.x-group-parameters}}
-
+        {{/vendorExtensions.x-streaming}}
+        {{^vendorExtensions.x-streaming}}
+                {{#returnType}}{{{returnType}}} response = {{/returnType}}api.{{operationId}}{{^vendorExtensions.x-group-parameters}}({{#allParams}}{{paramName}}{{^-last}}, {{/-last}}{{/allParams}});{{/vendorExtensions.x-group-parameters}}{{#vendorExtensions.x-group-parameters}}({{#requiredParams}}{{paramName}}{{^-last}}, {{/-last}}{{/requiredParams}}){{#optionalParams}}
+                .{{paramName}}({{paramName}}){{/optionalParams}}
+                .execute();{{/vendorExtensions.x-group-parameters}}
+        {{/vendorExtensions.x-streaming}}
         // TODO: test validations
     }
     {{/operation}}{{/operations}}

modules/openapi-generator/src/test/resources/3_0/streaming.yaml

@@ -0,0 +1,46 @@
+openapi: 3.0.1
+info:
+  title: ping some object
+  version: '1.0'
+servers:
+  - url: 'http://localhost:8082/'
+paths:
+  /ping:
+    post:
+      x-streaming: true
+      operationId: postPing
+      tags:
+      - ping
+      requestBody:
+        content:
+          'application/json':
+             schema:
+               $ref: "#/components/schemas/SomeObj"
+      responses:
+        '200':
+          description: OK
+          content:
+            'application/json':
+               schema:
+                 $ref: "#/components/schemas/SomeObj"
+components:
+  schemas:
+    SomeObj:
+      type: object
+      properties:
+        $_type:
+          type: string
+          # using 'enum' & 'default' for '$_type' is a work-around until constants are supported
+          # See https://github.com/OAI/OpenAPI-Specification/issues/1313
+          enum:
+          - SomeObjIdentifier
+          default: SomeObjIdentifier
+        id:
+          type: integer
+          format: int64
+        name:
+          type: string
+        active:
+          type: boolean
+        type:
+          type: string