如何从Amazon S3下载文件? [英] How to download files from Amazon S3?

问题描述

我在名为BucketA的存储桶中有一个名为output的文件夹.我在output文件夹中有文件列表.如何使用AWS Java SDK将它们下载到我的本地计算机上?

I have a folder named output inside a bucket named BucketA. I have a list of files in output folder. How do I download them to my local machine using AWS Java SDK ?

下面是我的代码:

AmazonS3Client s3Client = new AmazonS3Client(credentials);
        File localFile = new File("/home/abc/Desktop/AmazonS3/");
        s3Client.getObject(new GetObjectRequest("bucketA", "/bucketA/output/"), localFile);

我得到了错误:

AmazonS3Exception: The specified key does not exist.

推荐答案

请记住，S3不是文件系统，但它是对象存储.两者之间存在巨大差异，一个是目录式活动根本无法正常工作.

Keep in mind that S3 is not a filesystem, but it is an object store. There's a huge difference between the two, one being that directory-style activities simply won't work.

假设您有一个S3存储桶，其中有两个对象:

Suppose you have an S3 bucket with two objects in it:

/path/to/file1.txt
/path/to/file2.txt

使用这些对象时，不能像使用文件系统目录中的文件那样简单地引用/path/to/.这是因为/path/to/不是目录，而只是很大的哈希表中键的一部分.这就是为什么错误消息指示 key 出现问题的原因.这些不是文件名路径，而是对象库中对象的键.

When working with these objects you can't simply refer to /path/to/ like you can when working with files in a filesystem directory. That's because /path/to/ is not a directory but just part of a key in a very large hash table. This is why the error message indicates an issue with a key. These are not filename paths but keys to objects within the object store.

要在/path/to/之类的位置复制所有文件，您需要分多个步骤执行.首先，您需要获取键以/path/to开头的所有对象的列表，然后需要遍历每个单独的对象并逐个复制它们.

In order to copy all the files in a location like /path/to/ you need to perform it in multiple steps. First, you need to get a listing of all the objects whose keys begin with /path/to, then you need to loop through each individual object and copy them one by one.

此处是类似的问题，其答案显示了如何使用Java从S3下载多个文件.

Here is a similar question with an answer that shows how to download multiple files from S3 using Java.

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