feat: add Apache Dubbo code generator with multi-registry support

- Add comprehensive Dubbo microservice code generator
- Support Zookeeper and Nacos registries with auto-dependency selection
- Implement version-aware dependency management (Dubbo 3.2 vs 3.3+)
- Generate service interfaces, implementations, and Spring Boot REST controllers
- Include complete Spring Boot application structure with configuration
- Add detailed documentation and usage examples
- Support async operations and generic response wrappers
- Provide flexible configuration options for packages, versions, and features

Author: redoom

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

@@ -27,6 +27,7 @@ org.openapitools.codegen.languages.CSharpClientCodegen
 org.openapitools.codegen.languages.CSharpFunctionsServerCodegen
 org.openapitools.codegen.languages.DartClientCodegen
 org.openapitools.codegen.languages.DartDioClientCodegen
+org.openapitools.codegen.languages.DubboCodegen
 org.openapitools.codegen.languages.EiffelClientCodegen
 org.openapitools.codegen.languages.ElixirClientCodegen
 org.openapitools.codegen.languages.ElmClientCodegen

modules/openapi-generator/src/main/resources/META-INF/services/org.openapitools.codegen.CodegenConfig

@@ -0,0 +1,347 @@
+# {{appName}}
+
+{{appDescription}}
+
+This is a microservice project based on Apache Dubbo, generated by [OpenAPI Generator](https://openapi-generator.tech).
+
+- API version: {{appVersion}}
+- Package version: {{packageVersion}}
+{{^hideGenerationTimestamp}}
+- Generator version: {{generatorVersion}}
+- Build date: {{generatedDate}}
+{{/hideGenerationTimestamp}}
+- Generator: {{generatorClass}}
+{{#externalDocumentationDescription}}
+For more information, please visit: [{{{externalDocumentationDescription}}}]({{{externalDocumentationURL}}})
+{{/externalDocumentationDescription}}
+
+## Technology Stack
+
+- **Framework**: Apache Dubbo {{dubboVersion}}
+{{#useSpringBoot}}
+- **Spring Boot**: {{#useSpringBoot3}}3.x{{/useSpringBoot3}}{{^useSpringBoot3}}2.x{{/useSpringBoot3}}
+{{/useSpringBoot}}
+- **Java**: {{#java8}}8+{{/java8}}{{^java8}}11+{{/java8}}
+- **Build Tool**: Maven 3.6+
+- **Registry**: {{registryAddress}}
+- **Serialization**: Jackson JSON
+
+## System Requirements
+
+Building and running this project requires:
+1. Java {{#java8}}8{{/java8}}{{^java8}}11{{/java8}}+
+2. Maven 3.6+
+3. Registry Center (Nacos or Zookeeper)
+
+## Quick Start
+
+### 1. Clone and Build Project
+
+```bash
+git clone <your-repo-url>
+cd {{artifactId}}
+mvn clean compile
+```
+
+### 2. Configure Registry Center
+
+#### Using Nacos (Recommended)
+```bash
+# Download and start Nacos
+wget https://github.com/alibaba/nacos/releases/download/2.2.4/nacos-server-2.2.4.tar.gz
+tar -xzf nacos-server-2.2.4.tar.gz
+cd nacos/bin
+# Linux/Mac
+./startup.sh -m standalone
+# Windows
+startup.cmd -m standalone
+```
+
+#### Using Zookeeper (Alternative)
+```bash
+# Download and start Zookeeper
+wget https://downloads.apache.org/zookeeper/zookeeper-3.8.2/apache-zookeeper-3.8.2-bin.tar.gz
+tar -xzf apache-zookeeper-3.8.2-bin.tar.gz
+cd apache-zookeeper-3.8.2-bin
+cp conf/zoo_sample.cfg conf/zoo.cfg
+bin/zkServer.sh start
+```
+
+### 3. Configure Application
+
+Edit the `src/main/resources/application.yml` file:
+
+```yaml
+# Dubbo Configuration
+dubbo:
+  application:
+    name: {{artifactId}}
+  registry:
+    # Using Nacos
+    address: nacos://127.0.0.1:8848
+    # Or using Zookeeper
+    # address: zookeeper://127.0.0.1:2181
+  protocol:
+    name: dubbo
+    port: 20880
+  provider:
+    timeout: 10000
+
+{{#useSpringBoot}}
+# Spring Boot Configuration
+server:
+  port: 8080
+
+spring:
+  application:
+    name: {{artifactId}}
+
+# Logging Configuration
+logging:
+  level:
+    com.alibaba.nacos: WARN
+    org.apache.dubbo: INFO
+    root: INFO
+{{/useSpringBoot}}
+```
+
+### 4. Start Application
+
+{{#useSpringBoot}}
+```bash
+# Using Spring Boot Maven plugin
+mvn spring-boot:run
+
+# Or build JAR and run
+mvn clean package
+java -jar target/{{artifactId}}-{{appVersion}}.jar
+```
+{{/useSpringBoot}}
+{{^useSpringBoot}}
+```bash
+# Build project
+mvn clean compile
+
+# Run main class
+mvn exec:java -Dexec.mainClass="{{package}}.Application"
+```
+{{/useSpringBoot}}
+
+## Project Structure
+
+```
+{{artifactId}}/
+├── src/main/java/{{package}}/
+{{#operations}}
+│   ├── api/
+│   │   ├── {{classname}}.java              # Service Interface
+│   │   └── {{classname}}DubboImpl.java     # Dubbo Service Implementation
+{{/operations}}
+{{#hasModel}}
+│   ├── model/                              # Data Models
+{{#models}}
+{{#model}}
+│   │   └── {{classname}}.java
+{{/model}}
+{{/models}}
+{{/hasModel}}
+│   └── Application.java                    # Main Application Class
+├── src/main/resources/
+│   └── application.yml                     # Application Configuration
+├── pom.xml                                 # Maven Configuration
+└── README.md                               # Project Documentation
+```
+
+## API Interfaces
+
+{{#apiDocumentationUrl}}
+For complete API documentation, please visit: [{{apiDocumentationUrl}}]({{apiDocumentationUrl}})
+{{/apiDocumentationUrl}}
+
+### Service Interfaces
+
+{{#operations}}
+#### {{classname}}
+{{#operation}}
+- **{{nickname}}**: {{summary}}
+  {{#notes}}
+  - Description: {{.}}
+  {{/notes}}
+{{/operation}}
+
+{{/operations}}
+
+## Development Guide
+
+### Implement Business Logic
+
+1. Implement specific business logic in the generated `*DubboImpl.java` classes
+2. Inject necessary business service dependencies
+3. Handle exceptions and error scenarios
+
+### Custom Configuration
+
+1. **Timeout Configuration**: Adjust `dubbo.provider.timeout` in `application.yml`
+2. **Thread Pool Configuration**: Configure `dubbo.provider.threads` and other parameters
+3. **Serialization Configuration**: Choose appropriate serialization method
+
+### Monitoring and Operations
+
+1. **Health Checks**: Dubbo provides built-in health check endpoints
+2. **Metrics Monitoring**: Integrate with Prometheus or other monitoring systems
+3. **Log Management**: Configure appropriate log levels and output formats
+
+## Testing
+
+```bash
+# Run unit tests
+mvn test
+
+# Run integration tests
+mvn integration-test
+```
+
+## Deployment
+
+### Development Environment
+```bash
+mvn spring-boot:run
+```
+
+### Production Environment
+```bash
+# Build production package
+mvn clean package -Pprod
+
+# Deploy using Docker
+docker build -t {{artifactId}}:{{appVersion}} .
+docker run -p 8080:8080 -p 20880:20880 {{artifactId}}:{{appVersion}}
+```
+
+## Generator Configuration Options
+
+This project supports the following OpenAPI Generator configuration options:
+
+### Basic Configuration
+- `title`: API service title name (Default: "OpenAPI Dubbo")
+- `basePackage`: Base package name (Default: "org.openapitools")
+- `configPackage`: Configuration class package name (Default: "org.openapitools.configuration")
+- `dubboVersion`: Dubbo version (Default: "3.2.0")
+
+### Generation Control
+- `interfaceOnly`: Generate interfaces only, no implementation classes (Default: false)
+- `serviceInterface`: Generate service interfaces (Default: true)
+- `serviceImplementation`: Generate service implementations (Default: true)
+- `async`: Use asynchronous methods (Default: false)
+- `useTags`: Use tags to create class names (Default: true)
+- `useGenericResponse`: Use generic response wrapper (Default: false)
+
+### Registry Configuration
+- `registry-address`: Registry address, supports full address format (Default: "zookeeper://127.0.0.1:2181")
+  - Zookeeper example: `zookeeper://127.0.0.1:2181`
+  - Nacos example: `nacos://127.0.0.1:8848`
+
+#### 📋 Automatic Dependency Adaptation by Version
+The generator automatically selects the correct dependencies based on Dubbo version:
+
+**Dubbo 3.2 and earlier versions**:
+- Zookeeper: `dubbo-dependencies-zookeeper` (Aggregation POM)
+- Nacos: `dubbo-registry-nacos` + `nacos-client:2.2.4`
+
+**Dubbo 3.3+ versions**:
+- Zookeeper: `dubbo-registry-zookeeper` + `dubbo-remoting-zookeeper-curator5`
+- Nacos: `dubbo-registry-nacos` + `nacos-client:2.5.0`
+
+### Date-Time Library Configuration
+- `dateLibrary`: Date-time library selection (Default: "java8")
+  - `java8`: Java 8 native JSR310 (Recommended, for JDK 1.8+)
+  - `java8-localdatetime`: Java 8 using LocalDateTime (For legacy applications only)
+  - `joda`: Joda time library (For legacy applications only)
+  - `legacy`: Traditional java.util.Date
+
+### Usage Examples
+
+#### 🔧 Dubbo 3.2 Version Example
+```bash
+# Using Zookeeper (3.2 version automatically uses dubbo-dependencies-zookeeper)
+java -jar openapi-generator-cli.jar generate \
+-i /Users/redoom/IdeaProjects/openapi.yaml \
+-g dubbo \
+-o /Users/redoom/IdeaProjects/openapi-test \
+--additional-properties=registry-address=zookeeper://127.0.0.1:2181 \
+--additional-properties=dubboVersion=3.2.0 \
+--additional-properties=dateLibrary=java8
+
+# Using Nacos (3.2 version uses nacos-client:2.2.4)
+java -jar openapi-generator-cli.jar generate \
+-i /Users/redoom/IdeaProjects/openapi.yaml \
+-g dubbo \
+-o /Users/redoom/IdeaProjects/openapi-test \
+--additional-properties=registry-address=nacos://127.0.0.1:8848 \
+--additional-properties=dubboVersion=3.2.0 \
+--additional-properties=dateLibrary=java8
+```
+
+#### 🚀 Dubbo 3.3+ Version Example
+```bash
+# Using Zookeeper (3.3+ version automatically uses new modular dependencies)
+java -jar openapi-generator-cli.jar generate \
+-i /Users/redoom/IdeaProjects/openapi.yaml \
+-g dubbo \
+-o /Users/redoom/IdeaProjects/openapi-test \
+--additional-properties=registry-address=zookeeper://127.0.0.1:2181 \
+--additional-properties=dubboVersion=3.3.0 \
+--additional-properties=dateLibrary=java8
+
+# Using Nacos (3.3+ version uses nacos-client:2.5.0)
+java -jar openapi-generator-cli.jar generate \
+-i /Users/redoom/IdeaProjects/openapi.yaml \
+-g dubbo \
+-o /Users/redoom/IdeaProjects/openapi-test \
+--additional-properties=registry-address=nacos://127.0.0.1:8848 \
+--additional-properties=dubboVersion=3.3.0 \
+--additional-properties=dateLibrary=java8
+```
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Registry Connection Failed**
+   - Check if the registry center is started
+   - Verify network connection and port configuration
+
+2. **Service Call Timeout**
+   - Adjust `dubbo.provider.timeout` settings
+   - Check network latency and service performance
+
+3. **Serialization Exception**
+   - Ensure all model classes implement `Serializable` interface
+   - Check Jackson configuration
+
+### Debug Logging
+
+Enable debug mode to see detailed logs:
+
+```yaml
+logging:
+  level:
+    org.apache.dubbo: DEBUG
+    {{package}}: DEBUG
+```
+
+## License
+
+This project is licensed under the [Apache License 2.0](LICENSE).
+
+## Contributing
+
+Issues and Pull Requests are welcome!
+
+## Contact
+
+{{#apiDocumentationUrl}}{{infoEmail}}{{/apiDocumentationUrl}}
+
+---
+
+> This project is automatically generated by OpenAPI Generator, based on Apache Dubbo microservice architecture.