<dependency>
    <groupId>com.theokanning.openai-gpt3-java</groupId>
    <artifactId>service</artifactId>
    <version>0.12.0</version>
</dependency>

openai.api-key=your-api-key-here

import com.theokanning.openai.service.OpenAiService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class OpenAiConfig {
    @Value("${openai.api-key}")
    private String apiKey;
    @Bean
    public OpenAiService openAiService() {
        return new OpenAiService(apiKey);
    }
}

import com.theokanning.openai.completion.CompletionRequest;
import com.theokanning.openai.service.OpenAiService;
import org.springframework.stereotype.Service;
@Service
public class OpenAiService {
    private final OpenAiService openAiService;
    public OpenAiService(OpenAiService openAiService) {
        this.openAiService = openAiService;
    }
    public String generateText(String prompt) {
        CompletionRequest completionRequest = CompletionRequest.builder()
                .prompt(prompt)
                .model("text-davinci-003")
                .maxTokens(100)
                .build();
        return openAiService.createCompletion(completionRequest).getChoices().get(0).getText();
    }
}

import org.springframework.web.bind.annotation.*;
@RestController
@RequestMapping("/api/generate")
public class OpenAiController {
    private final OpenAiService openAiService;
    public OpenAiController(OpenAiService openAiService) {
        this.openAiService = openAiService;
    }
    @PostMapping("/text")
    public String generateText(@RequestBody String prompt) {
        return openAiService.generateText(prompt);
    }
}

curl -X POST -H "Content-Type: text/plain" -d "Once upon a time" http://localhost:8080/api/generate/text