如何使用 SseEmitter 实现 Spring Boot 后端的流式传输和前端的数据接收

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

@RestController
@RequestMapping("/api/chat")
public class ChatController {
    @GetMapping("/stream")
    public SseEmitter streamResponse() {
        SseEmitter emitter = new SseEmitter(0L); // 0L 表示永不超时
        Executors.newSingleThreadExecutor().execute(() -> {
            try {
                for (int i = 1; i <= 5; i++) {
                    emitter.send("消息 " + i);
                    Thread.sleep(1000); // 模拟延迟
                }
                emitter.complete();
            } catch (Exception e) {
                emitter.completeWithError(e);
            }
        });
        return emitter;
    }
}

async function fetchStreamData() {
    const response = await fetch("/api/chat/stream");
    // 确保服务器支持流式数据
    if (!response.ok) {
        throw new Error(`HTTP 错误！状态码: ${response.status}`);
    }
    const reader = response.body.getReader();
    const decoder = new TextDecoder("utf-8");
    // 读取流式数据
    while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        // 解码并输出数据
        const text = decoder.decode(value, { stream: true });
        console.log("收到数据:", text);
    }
    console.log("流式传输完成");
}
// 调用流式请求
fetchStreamData().catch(console.error);