异步文件 I/O 支持¶
Asynchronous file I/O support
AnyIO 提供了阻塞文件操作的异步包装器。这些包装器在工作线程中运行阻塞操作。
示例:
from anyio import open_file, run
async def main():
async with await open_file('/some/path/somewhere') as f:
contents = await f.read()
print(contents)
run(main)
这些包装器还支持按行异步迭代文件内容，就像标准文件对象支持同步迭代一样:
from anyio import open_file, run
async def main():
async with await open_file('/some/path/somewhere') as f:
async for line in f:
print(line, end='')
run(main)
要将现有的打开文件对象包装为异步文件，可以使用 wrap_file():
from anyio import wrap_file, run
async def main():
with open('/some/path/somewhere') as f:
async for line in wrap_file(f):
print(line, end='')
run(main)
备注
关闭包装器时，也会关闭底层的同步文件对象。
参见
AnyIO provides asynchronous wrappers for blocking file operations. These wrappers run blocking operations in worker threads.
Example:
from anyio import open_file, run
async def main():
async with await open_file('/some/path/somewhere') as f:
contents = await f.read()
print(contents)
run(main)
The wrappers also support asynchronous iteration of the file line by line, just as the standard file objects support synchronous iteration:
from anyio import open_file, run
async def main():
async with await open_file('/some/path/somewhere') as f:
async for line in f:
print(line, end='')
run(main)
To wrap an existing open file object as an asynchronous file, you can use
wrap_file():
from anyio import wrap_file, run
async def main():
with open('/some/path/somewhere') as f:
async for line in wrap_file(f):
print(line, end='')
run(main)
备注
Closing the wrapper also closes the underlying synchronous file object.
参见
异步路径操作¶
Asynchronous path operations
AnyIO 提供了 pathlib.Path 类的异步版本。它与原版有一些不同之处：
执行磁盘 I/O 操作的方法（如
read_bytes()）会在工作线程中运行，因此需要使用await正常返回
pathlib.Path对象的属性和方法，现在返回Path对象Python 3.10 API 中的方法和属性在所有版本中均可用
不支持作为上下文管理器使用，因为在 pathlib 中已被弃用
例如，创建一个包含二进制内容的文件可以这样做:
from anyio import Path, run
async def main():
path = Path('/foo/bar')
await path.write_bytes(b'hello, world')
run(main)
异步迭代目录内容可以按如下方式进行:
from anyio import Path, run
async def main():
# 打印目录 /foo/bar 中每个文件的内容（假定是文本文件）
dir_path = Path('/foo/bar')
async for path in dir_path.iterdir():
if await path.is_file():
print(await path.read_text())
print('---------------------')
run(main)
AnyIO provides an asynchronous version of the pathlib.Path class. It differs
with the original in a number of ways:
Operations that perform disk I/O (like
read_bytes()) are run in a
worker thread and thus require an await
* Methods like glob() return an asynchronous iterator that yields
asynchronous Path objects
* Properties and methods that normally return pathlib.Path objects return
Path objects instead
* Methods and properties from the Python 3.10 API are available on all versions
* Use as a context manager is not supported, as it is deprecated in pathlib
For example, to create a file with binary content:
from anyio import Path, run
async def main():
path = Path('/foo/bar')
await path.write_bytes(b'hello, world')
run(main)
Asynchronously iterating a directory contents can be done as follows:
from anyio import Path, run
async def main():
# Print the contents of every file (assumed to be text) in the directory /foo/bar
dir_path = Path('/foo/bar')
async for path in dir_path.iterdir():
if await path.is_file():
print(await path.read_text())
print('---------------------')
run(main)