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语音合成（TTS）API
Spring AI 通过 TextToSpeechModel 和 StreamingTextToSpeechModel 接口为文本转语音（TTS）提供了一个统一的API。这使您能够编写可跨不同TTS提供商工作的可移植代码。
公共接口
所有TTS提供商都实现了以下共享接口：
语音合成模型
TextToSpeechModel 接口提供了将文本转换为语音的方法:
public interface TextToSpeechModel extends Model<TextToSpeechPrompt, TextToSpeechResponse>, StreamingTextToSpeechModel {
/**
* Converts text to speech with default options.
*/
default byte[] call(String text) {
// Default implementation
}
/**
* Converts text to speech with custom options.
*/
TextToSpeechResponse call(TextToSpeechPrompt prompt);
/**
* Returns the default options for this model.
*/
default TextToSpeechOptions getDefaultOptions() {
// Default implementation
}
}流式文本转语音模型
StreamingTextToSpeechModel 接口提供了实时流式音频的方法:
@FunctionalInterface
public interface StreamingTextToSpeechModel extends StreamingModel<TextToSpeechPrompt, TextToSpeechResponse> {
/**
* Streams text-to-speech responses with metadata.
*/
Flux<TextToSpeechResponse> stream(TextToSpeechPrompt prompt);
/**
* Streams audio bytes for the given text.
*/
default Flux<byte[]> stream(String text) {
// Default implementation
}
}编写与提供者无关的代码
共享TTS接口的主要优势之一是能够编写代码，使其无需修改即可与任何TTS服务提供商协同工作。实际的服务提供商（如OpenAI、ElevenLabs等）由您的Spring Boot配置决定，这意味着您可以切换提供商而无需更改应用程序代码。
基础服务示例
共享接口使您能够编写可与任何TTS提供商配合使用的代码：
@Service
public class NarrationService {
private final TextToSpeechModel textToSpeechModel;
public NarrationService(TextToSpeechModel textToSpeechModel) {
this.textToSpeechModel = textToSpeechModel;
}
public byte[] narrate(String text) {
// Works with any TTS provider
return textToSpeechModel.call(text);
}
public byte[] narrateWithOptions(String text, TextToSpeechOptions options) {
TextToSpeechPrompt prompt = new TextToSpeechPrompt(text, options);
TextToSpeechResponse response = textToSpeechModel.call(prompt);
return response.getResult().getOutput();
}
}此服务无缝集成OpenAI、ElevenLabs或任何其他TTS提供商，具体实现由您的Spring Boot配置决定。
高级示例：多提供者支持
您可以构建同时支持多个TTS提供商的应用程序：
@Service
public class MultiProviderNarrationService {
private final Map<String, TextToSpeechModel> providers;
public MultiProviderNarrationService(List<TextToSpeechModel> models) {
// Spring will inject all available TextToSpeechModel beans
this.providers = models.stream()
.collect(Collectors.toMap(
model -> model.getClass().getSimpleName(),
model -> model
));
}
public byte[] narrateWithProvider(String text, String providerName) {
TextToSpeechModel model = providers.get(providerName);
if (model == null) {
throw new IllegalArgumentException("Unknown provider: " + providerName);
}
return model.call(text);
}
public Set<String> getAvailableProviders() {
return providers.keySet();
}
}流式音频示例
共享接口同样支持流式传输，以实现实时音频生成：
@Service
public class StreamingNarrationService {
private final TextToSpeechModel textToSpeechModel;
public StreamingNarrationService(TextToSpeechModel textToSpeechModel) {
this.textToSpeechModel = textToSpeechModel;
}
public Flux<byte[]> streamNarration(String text) {
// TextToSpeechModel extends StreamingTextToSpeechModel
return textToSpeechModel.stream(text);
}
public Flux<TextToSpeechResponse> streamWithMetadata(String text, TextToSpeechOptions options) {
TextToSpeechPrompt prompt = new TextToSpeechPrompt(text, options);
return textToSpeechModel.stream(prompt);
}
}REST控制器示例
使用提供商无关的TTS构建REST API：
@RestController
@RequestMapping("/api/tts")
public class TextToSpeechController {
private final TextToSpeechModel textToSpeechModel;
public TextToSpeechController(TextToSpeechModel textToSpeechModel) {
this.textToSpeechModel = textToSpeechModel;
}
@PostMapping(value = "/synthesize", produces = "audio/mpeg")
public ResponseEntity<byte[]> synthesize(@RequestBody SynthesisRequest request) {
byte[] audio = textToSpeechModel.call(request.text());
return ResponseEntity.ok()
.contentType(MediaType.parseMediaType("audio/mpeg"))
.header("Content-Disposition", "attachment; filename=\"speech.mp3\"")
.body(audio);
}
@GetMapping(value = "/stream", produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public Flux<byte[]> streamSynthesis(@RequestParam String text) {
return textToSpeechModel.stream(text);
}
record SynthesisRequest(String text) {}
}基于配置的提供者选择
使用 Spring 配置文件或属性在提供程序之间切换：
# application-openai.yml
spring:
ai:
model:
audio:
speech: openai
openai:
api-key: ${OPENAI_API_KEY}
audio:
speech:
options:
model: gpt-4o-mini-tts
voice: alloy
# application-elevenlabs.yml
spring:
ai:
model:
audio:
speech: elevenlabs
elevenlabs:
api-key: ${ELEVENLABS_API_KEY}
tts:
options:
model-id: eleven_turbo_v2_5
voice-id: your_voice_id然后激活所需的提供者：
# Use OpenAI
java -jar app.jar --spring.profiles.active=openai
# Use ElevenLabs
java -jar app.jar --spring.profiles.active=elevenlabs使用可移植选项
为了最大程度的可移植性，请仅使用通用的 TextToSpeechOptions 接口方法:
@Service
public class PortableNarrationService {
private final TextToSpeechModel textToSpeechModel;
public PortableNarrationService(TextToSpeechModel textToSpeechModel) {
this.textToSpeechModel = textToSpeechModel;
}
public byte[] createPortableNarration(String text) {
// Use provider's default options for maximum portability
TextToSpeechOptions defaultOptions = textToSpeechModel.getDefaultOptions();
TextToSpeechPrompt prompt = new TextToSpeechPrompt(text, defaultOptions);
TextToSpeechResponse response = textToSpeechModel.call(prompt);
return response.getResult().getOutput();
}
}使用提供商特定功能
当您需要使用特定于提供商的功能时，您仍然可以在保持代码可移植性的同时使用它们。
@Service
public class FlexibleNarrationService {
private final TextToSpeechModel textToSpeechModel;
public FlexibleNarrationService(TextToSpeechModel textToSpeechModel) {
this.textToSpeechModel = textToSpeechModel;
}
public byte[] narrate(String text, TextToSpeechOptions baseOptions) {
TextToSpeechOptions options = baseOptions;
// Apply provider-specific optimizations if available
if (textToSpeechModel instanceof OpenAiAudioSpeechModel) {
options = OpenAiAudioSpeechOptions.builder()
.from(baseOptions)
.model("gpt-4o-tts") // OpenAI-specific: use high-quality model
.speed(1.0)
.build();
} else if (textToSpeechModel instanceof ElevenLabsTextToSpeechModel) {
// ElevenLabs-specific options could go here
}
TextToSpeechPrompt prompt = new TextToSpeechPrompt(text, options);
TextToSpeechResponse response = textToSpeechModel.call(prompt);
return response.getResult().getOutput();
}
}提供商特定功能
共享接口提供了可移植性，但每个提供商也通过特定于提供商的选项类（例如，OpenAiAudioSpeechOptions、ElevenLabsSpeechOptions）提供了特定功能。这些类实现了TextToSpeechOptions接口的同时增加了特定于提供商的功能。