Python使用fastAPI实现一个流式传输接口

1. 使用fastapi实现流式传输

1.1 服务端 fastapi_server.py

编写服务端代码fastapi_server.py。服务端代码主要使用了fastapi和uvicorn两个库。

#!/usr/bin/env python
# coding=utf-8
# @Time    : 2024/1/31 19:13
# @Software: PyCharm
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
import time
import uvicorn

app = FastAPI()


async def generate_data():
    for i in range(1, 11):
        time.sleep(1)  # 模拟每秒生成一个块的耗时操作
        yield f"FASTAPI Chunk {i}\n"


@app.get("/stream")
async def stream_data():
    return StreamingResponse(generate_data(), media_type="text/plain")


if __name__ == "__main__":
    uvicorn.run(app, host="127.0.0.1", port=8001)

1.2客户端 （requests）

使用python编写一个客户端stream_client.py，进行流式接收。

#!/usr/bin/env python
# coding=utf-8
# @Time    : 2024/1/31 19:14
#
# stream_client.py


import requests

url = "http://127.0.0.1:8001/stream/"  # 替换为你的实际接口地址


def test1():
    try:
        response = requests.get(url, stream=True) # stream参数为True

        if response.status_code == 200:
            for chunk in response.iter_content(chunk_size=7):  # 这行很重要哦
                if chunk:
                    print(chunk.decode("utf-8"), end="")
    except requests.RequestException as e:
        print(f"Request failed: {e}")


def test2():
    try:
        response = requests.get(url, stream=True)

        if response.status_code == 200:
            for line in response.iter_lines(decode_unicode=True, chunk_size=8):
                if line:
                    print("Received SSE event:", line)
    except requests.RequestException as e:
        print(f"Request failed: {e}")


# test1()
test2()

1.3 在html中流式显示

新建一个client.html文件，放在fastapi_server.py目录下。同时修改fastapi_server.py, 增加一个BlockIterator迭代器对长文本进行切块。

    
    
    
    


aaa

服务端增加一个/web_client接口，读取上述网页内容

#!/usr/bin/env python
# coding=utf-8
# @Time    : 2024/1/31 19:13
# @Software: PyCharm
from fastapi import FastAPI
from starlette.responses import HTMLResponse
from fastapi.responses import StreamingResponse
import time
import uvicorn

app = FastAPI()

CONTENT = """《易经》被誉为诸经之首，大道之源，是中华优秀传统文化的总纲领，是中华民族五千年智慧的结晶。他含盖万有、纲纪群伦，是中华文化的杰出代表；他博大精微、包罗万象，亦是中华文明的源头。其内容涉及哲学、生命、自然、科学、政治、天文、地理、文学、艺术等诸多领域，是各家共同的经典。
《易经》包括《连山》《归藏》《周易》三部易书，现存于世的只有《周易》。《周易》相传是周文王被囚羑里时，研究《易经》所作的结论。"""


class BlockIterator:
    def __init__(self, text, block_size=10):
        self.text = text
        self.block_size = block_size
        self.index = 0

    def __iter__(self):
        return self

    def __next__(self):
        if self.index >= len(self.text):
            raise StopIteration

        block = self.text[self.index:self.index + self.block_size]
        self.index += self.block_size
        return block


async def generate_data():
    for i in BlockIterator(CONTENT, block_size=1):
        time.sleep(0.05)  # 模拟每秒生成一个块的耗时操作
        # yield f"FASTAPI Chunk {i}\n"
        yield i


@app.get("/web_client", response_class=HTMLResponse)
async def read_root():
    with open("static/client.html", "r") as file:
        html_content = file.read()
        html_content = html_content.replace("$FASTAPI$", "http://127.0.0.1:8001/stream/")
    return HTMLResponse(content=html_content)


@app.get("/stream")
async def stream_data():
    return StreamingResponse(generate_data(), media_type="text/plain")


if __name__ == "__main__":
    uvicorn.run(app, host="127.0.0.1", port=8001)