|
| 1 | +from flask import Flask, request, send_file, Response |
| 2 | +import os |
| 3 | +import time |
| 4 | +from threading import Lock |
| 5 | + |
| 6 | +app = Flask(__name__) |
| 7 | + |
| 8 | +# 限速配置 (10KB/s) |
| 9 | +LIMIT_BYTES_PER_SECOND = 100 * 1024 # 10KB |
| 10 | +CHUNK_SIZE = 1024 # 每次发送1KB |
| 11 | +SLEEP_INTERVAL = CHUNK_SIZE / LIMIT_BYTES_PER_SECOND # 每次发送后的休眠时间 |
| 12 | + |
| 13 | +# 存储要提供下载的文件目录 |
| 14 | +UPLOAD_FOLDER = "files_to_serve" |
| 15 | +os.makedirs(UPLOAD_FOLDER, exist_ok=True) |
| 16 | + |
| 17 | +# 用于控制并发下载的锁 |
| 18 | +download_lock = Lock() |
| 19 | + |
| 20 | + |
| 21 | +def get_file_path(filename): |
| 22 | + """获取文件的完整路径""" |
| 23 | + return os.path.join(UPLOAD_FOLDER, filename) |
| 24 | + |
| 25 | + |
| 26 | +def rate_limited_file_reader(file_path): |
| 27 | + """生成器函数,限速读取文件内容""" |
| 28 | + with open(file_path, "rb") as f: |
| 29 | + while True: |
| 30 | + data = f.read(CHUNK_SIZE) |
| 31 | + if not data: |
| 32 | + break |
| 33 | + yield data |
| 34 | + # 控制速度:每发送CHUNK_SIZE字节后休眠相应时间 |
| 35 | + time.sleep(SLEEP_INTERVAL) |
| 36 | + |
| 37 | + |
| 38 | +@app.route("/files/<filename>") |
| 39 | +def serve_file(filename): |
| 40 | + """提供文件下载,限速10KB/s""" |
| 41 | + file_path = get_file_path(filename) |
| 42 | + |
| 43 | + # 检查文件是否存在 |
| 44 | + if not os.path.exists(file_path): |
| 45 | + return f"文件 {filename} 不存在", 404 |
| 46 | + |
| 47 | + # 获取文件大小 |
| 48 | + file_size = os.path.getsize(file_path) |
| 49 | + |
| 50 | + # 设置响应头 |
| 51 | + headers = { |
| 52 | + "Content-Disposition": f'attachment; filename="{filename}"', |
| 53 | + "Content-Length": str(file_size), |
| 54 | + "Accept-Ranges": "bytes", # 支持断点续传 |
| 55 | + } |
| 56 | + |
| 57 | + # 使用限速生成器提供文件内容 |
| 58 | + return Response( |
| 59 | + rate_limited_file_reader(file_path), |
| 60 | + headers=headers, |
| 61 | + mimetype="application/octet-stream", |
| 62 | + ) |
| 63 | + |
| 64 | + |
| 65 | +@app.route("/range-test/<filename>") |
| 66 | +def range_test(filename): |
| 67 | + """测试断点续传支持的端点""" |
| 68 | + file_path = get_file_path(filename) |
| 69 | + |
| 70 | + if not os.path.exists(file_path): |
| 71 | + return f"文件 {filename} 不存在", 404 |
| 72 | + |
| 73 | + file_size = os.path.getsize(file_path) |
| 74 | + range_header = request.headers.get("Range", None) |
| 75 | + |
| 76 | + # 如果没有Range头,返回完整文件 |
| 77 | + if not range_header: |
| 78 | + headers = { |
| 79 | + "Content-Disposition": f'attachment; filename="{filename}"', |
| 80 | + "Content-Length": str(file_size), |
| 81 | + "Accept-Ranges": "bytes", |
| 82 | + } |
| 83 | + return Response( |
| 84 | + rate_limited_file_reader(file_path), |
| 85 | + headers=headers, |
| 86 | + mimetype="application/octet-stream", |
| 87 | + ) |
| 88 | + |
| 89 | + # 处理Range请求 |
| 90 | + try: |
| 91 | + # 解析Range头 (格式: bytes=start-end) |
| 92 | + range_start, range_end = range_header.replace("bytes=", "").split("-") |
| 93 | + range_start = int(range_start) |
| 94 | + range_end = int(range_end) if range_end else file_size - 1 |
| 95 | + |
| 96 | + # 确保范围有效 |
| 97 | + if range_start > range_end or range_start >= file_size: |
| 98 | + return "Invalid range", 416 |
| 99 | + |
| 100 | + # 调整结束范围 |
| 101 | + range_end = min(range_end, file_size - 1) |
| 102 | + |
| 103 | + # 生成部分文件内容的生成器 |
| 104 | + def limited_range_reader(): |
| 105 | + with open(file_path, "rb") as f: |
| 106 | + f.seek(range_start) |
| 107 | + remaining = range_end - range_start + 1 |
| 108 | + while remaining > 0: |
| 109 | + read_size = min(remaining, CHUNK_SIZE) |
| 110 | + data = f.read(read_size) |
| 111 | + if not data: |
| 112 | + break |
| 113 | + yield data |
| 114 | + remaining -= read_size |
| 115 | + time.sleep(SLEEP_INTERVAL) |
| 116 | + |
| 117 | + # 返回部分内容 |
| 118 | + headers = { |
| 119 | + "Content-Disposition": f'attachment; filename="{filename}"', |
| 120 | + "Content-Range": f"bytes {range_start}-{range_end}/{file_size}", |
| 121 | + "Content-Length": str(range_end - range_start + 1), |
| 122 | + "Accept-Ranges": "bytes", |
| 123 | + } |
| 124 | + |
| 125 | + return Response( |
| 126 | + limited_range_reader(), |
| 127 | + status=206, # Partial Content |
| 128 | + headers=headers, |
| 129 | + mimetype="application/octet-stream", |
| 130 | + ) |
| 131 | + |
| 132 | + except Exception as e: |
| 133 | + return f"处理范围请求时出错: {str(e)}", 400 |
| 134 | + |
| 135 | + |
| 136 | +@app.route("/no-range/<filename>") |
| 137 | +def no_range_serve(filename): |
| 138 | + """提供文件下载但不支持断点续传,用于测试兼容性""" |
| 139 | + file_path = get_file_path(filename) |
| 140 | + |
| 141 | + if not os.path.exists(file_path): |
| 142 | + return f"文件 {filename} 不存在", 404 |
| 143 | + |
| 144 | + file_size = os.path.getsize(file_path) |
| 145 | + |
| 146 | + # 不设置Accept-Ranges头,表示不支持断点续传 |
| 147 | + headers = { |
| 148 | + "Content-Disposition": f'attachment; filename="{filename}"', |
| 149 | + "Content-Length": str(file_size), |
| 150 | + # 注意:这里没有设置Accept-Ranges头 |
| 151 | + } |
| 152 | + |
| 153 | + return Response( |
| 154 | + rate_limited_file_reader(file_path), |
| 155 | + headers=headers, |
| 156 | + mimetype="application/octet-stream", |
| 157 | + ) |
| 158 | + |
| 159 | + |
| 160 | +if __name__ == "__main__": |
| 161 | + print(f"限速文件服务器启动中...") |
| 162 | + print( |
| 163 | + f"限速: {LIMIT_BYTES_PER_SECOND} bytes/s ({LIMIT_BYTES_PER_SECOND/1024:.2f}KB/s)" |
| 164 | + ) |
| 165 | + print(f"请将测试文件放入 {UPLOAD_FOLDER} 目录") |
| 166 | + print(f"访问 http://localhost:5000/files/文件名 以下载文件(支持断点续传)") |
| 167 | + print(f"访问 http://localhost:5000/no-range/文件名 以下载文件(不支持断点续传)") |
| 168 | + app.run(host="0.0.0.0", port=5000, debug=True) |
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