如何从用 Java 编写的 AWS Lambda 函数读取 S3 文件？
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How to read S3 file from AWS Lambda Function written in Java?
提问by Sumit Arora
I have written a AWS Lambda Function, Its objective is that on invocation - it read the contents of a file say x.db, get a specific value out of it and return to the caller.But this x.db file changes time to time. So I would like to upload this x.db file to S3 and read it from AWS Lambda function as like reading a file.
我编写了一个 AWS Lambda 函数，它的目标是在调用时 - 它读取文件的内容，比如 x.db，从中获取特定值并返回给调用者。但是这个 x.db 文件会不时更改. 所以我想将此 x.db 文件上传到 S3 并从 AWS Lambda 函数中读取它，就像读取文件一样。
File xFile = new File("S3 file in x.db");
How to read such x.db S3 file from AWS Lambda Function written in Java ?
如何从用 Java 编写的 AWS Lambda 函数读取这样的 x.db S3 文件？
回答by ataylor
Use the Java S3 SDK. If you upload a file called x.dbto an S3 bucket mybucket, it would look something like this:
使用 Java S3 SDK。如果您上传一个名为x.dbS3 存储桶的文件mybucket，它将如下所示：
import com.amazonaws.services.s3.*;
import com.amazonaws.services.s3.model.*;
...
AmazonS3 client = new AmazonS3Client();
S3Object xFile = client.getObject("mybucket", "x.db");
InputStream contents = xFile.getObjectContent();
In addition, you should ensure the role you've assigned to your lambda function has access to the S3 bucket. Apply a policy like this:
此外，您应该确保分配给 lambda 函数的角色可以访问 S3 存储桶。应用这样的策略：
"Version": "2012-10-17",
"Statement": [{
"Effect": "Allow",
"Action": [
"s3:*"
],
"Resource": [
"arn:aws:s3:::mybucket",
"arn:aws:s3:::mybucket/*"
]
}]
