La descarga por streaming permite descargar un objeto como flujos de datos en incrementos. Si necesita descargar un objeto grande o si la descarga requiere mucho tiempo, utilice este método para obtener el objeto en incrementos.
Notas
En este tema se utiliza el endpoint público de la región China (Hangzhou). Si desea acceder a OSS desde otros servicios de Alibaba Cloud en la misma región, utilice un endpoint interno. Para obtener más información sobre las regiones y endpoints de OSS, consulte Regions and endpoints.
Este tema muestra cómo crear una instancia de OSSClient con un endpoint de OSS. Para configuraciones alternativas, como usar un dominio personalizado o autenticarse con credenciales de Security Token Service (STS), consulte Initialization.
Para utilizar la descarga por streaming, debe contar con el permiso
oss:GetObject. Para obtener más información, consulte Grant a custom policy.
Código de ejemplo
A continuación código de ejemplo muestra cómo descargar por streaming un objeto llamado exampleobject.txt desde un bucket llamado examplebucket:
# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Create a server object.
# Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com.
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
# Specify the ID of the region that maps to the endpoint. Example: cn-hangzhou. This parameter is required if you use the signature algorithm V4.
region = "cn-hangzhou"
# Specify the name of your bucket.
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)
# The value returned by bucket.get_object is a file-like object that can be iterated.
# Specify the full path of the object. Do not include the bucket name in the full path of the object.
object_stream = bucket.get_object('exampleobject.txt')
print(object_stream.read())
# You must call the read() operation to read the object from the stream returned by get_object before you can calculate the CRC-64 value of the object.
if object_stream.client_crc != object_stream.server_crc:
print("The CRC checksum between client and server is inconsistent!")A continuación código de ejemplo muestra cómo descargar los datos de un objeto llamado exampleobject.txt desde un flujo hacia un archivo llamado examplefile.txt en el directorio D:\localpath:
import shutil
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Create a server object.
# Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com.
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
# Specify the ID of the region that maps to the endpoint. Example: cn-hangzhou. This parameter is required if you use the signature algorithm V4.
region = "cn-hangzhou"
# Specify the name of your bucket.
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)
# object_stream is a file-like object. You can use the shutil.copyfileobj method to download the data from a stream to the local file.
# Specify the full path of the object. Do not include the bucket name in the full path of the object.
object_stream = bucket.get_object('exampleobject.txt')
# Download the object as a local file in the specified path. If a file that has the same name already exists in the specified path, the downloaded object overwrites the file. Otherwise, the downloaded file is saved in the path.
# If you do not specify a path for the downloaded object, the downloaded object is saved to the path of the project to which the sample program belongs.
with open('D:\\localpath\\examplefile.txt', 'wb') as local_fileobj:
shutil.copyfileobj(object_stream, local_fileobj)A continuación código de ejemplo muestra cómo copiar los datos de un objeto llamado exampleobject.txt desde un flujo hacia un objeto llamado exampleobjectnew.txt:
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Create a server object.
# Obtain access credentials from environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured.
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())
# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com.
endpoint = "https://oss-cn-hangzhou.aliyuncs.com"
# Specify the ID of the region that maps to the endpoint. Example: cn-hangzhou. This parameter is required if you use the signature algorithm V4.
region = "cn-hangzhou"
# Specify the name of your bucket.
bucket = oss2.Bucket(auth, endpoint, "yourBucketName", region=region)
# object_stream is an iterable object. You can copy the data of the object from a stream to another object in the same bucket.
# Specify the full path of the object. Do not include the bucket name in the full path of the object.
object_stream = bucket.get_object('exampleobject.txt')
# Specify the full path of the destination object. Do not include the bucket name in the full path of the object.
bucket.put_object('exampleobjectnew.txt', object_stream)