从环境变量中获取值 - AWS Cloud Development Kit (AWS CDK) v2

这是 AWS CDK v2 开发者指南。旧版 CDK v1 于 2022 年 6 月 1 日进入维护阶段，并于 2023 年 6 月 1 日终止支持。

本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。

从环境变量中获取值

要获取环境变量的值，请使用如下代码。此代码将获取环境变量 amzn-s3-demo-bucket 的值。

TypeScript
// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
JavaScript
// Sets bucket_name to undefined if environment variable not set
var bucket_name = process.env.amzn-s3-demo-bucket;

// Sets bucket_name to a default if env var doesn't exist
var bucket_name = process.env.amzn-s3-demo-bucket || "DefaultName";
Python
import os

# Raises KeyError if environment variable doesn't exist
bucket_name = os.environ["amzn-s3-demo-bucket"]

# Sets bucket_name to None if environment variable doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket")

# Sets bucket_name to a default if env var doesn't exist
bucket_name = os.getenv("amzn-s3-demo-bucket", "DefaultName")
Java
// Sets bucketName to null if environment variable doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");

// Sets bucketName to a default if env var doesn't exist
String bucketName = System.getenv("amzn-s3-demo-bucket");
if (bucketName == null) bucketName = "DefaultName";
C#
using System;

// Sets bucket name to null if environment variable doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket");

// Sets bucket_name to a default if env var doesn't exist
string bucketName = Environment.GetEnvironmentVariable("amzn-s3-demo-bucket") ?? "DefaultName";