读取内存

Question

我正在尝试使用Rusoto从存储桶中下载文件，并且正在获取文件内容：

fn get_object(client: &TestClient, bucket: &str, filename: &str) {
    let get_req = GetObjectRequest {
        bucket: bucket.to_owned(),
        key: filename.to_owned(),
        ..Default::default()
    };

    let result = client.get_object(&get_req).sync().expect("Couldn't GET object");


    let stream = result.body.unwrap();
    let body = stream.concat2().wait().unwrap();

    assert!(body.len() > 0);
}

如何将这个GetObjectOutput(result)对象保存到文件中？

Answer 1

Rusoto现在使用标准库期货，并且不再提供sync方法，因此先前的答案不再有效。

读取内存

use futures::stream::TryStreamExt;
use rusoto_core::Region;
use rusoto_s3::{GetObjectRequest, S3Client, S3};

type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;

const BUCKET_NAME: &str = "my very own bucket name";

#[tokio::main]
async fn main() -> Result<()> {
    let client = S3Client::new(Region::UsEast2);

    let mut object = client
        .get_object(GetObjectRequest {
            bucket: BUCKET_NAME.into(),
            ..Default::default()
        })
        .await?;

    let body = object.body.take().expect("The object has no body");

    let body = body.map_ok(|b| b.to_vec()).try_concat().await?;
    println!("body length: {}", body.len());

    Ok(())
}

需要指定

AWS_ACCESS_KEY_ID和AWS_SECRET_ACCESS_KEY。我选择在代码之外设置环境变量。

流式传输文件

use rusoto_core::Region;
use rusoto_s3::{GetObjectRequest, S3Client, S3};
use tokio::{fs::File, io};

type Error = Box<dyn std::error::Error>;
type Result<T, E = Error> = std::result::Result<T, E>;

const BUCKET_NAME: &str = "my very own bucket name";

#[tokio::main]
async fn main() -> Result<()> {
    let client = S3Client::new(Region::UsEast2);

    let mut object = client
        .get_object(GetObjectRequest {
            bucket: BUCKET_NAME.into(),
            ..Default::default()
        })
        .await?;

    let body = object.body.take().expect("The object has no body");

    let mut body = body.into_async_read();
    let mut file = File::create("/tmp/a-place-to-write").await?;
    io::copy(&mut body, &mut file).await?;

    Ok(())
}

尽管ByteStream具有诱人的into_blocking_read方法，但我不建议您使用它。如果尝试在异步上下文中使用它，则会出现恐慌，因为它会启动嵌套的Tokio执行程序。如果您在异步上下文之外使用它，则它将truncate the data，除非您非常注意使异步运行时在周围，但不要在其内部。

另请参阅：

依赖版本

[dependencies]
rusoto_s3 = "0.43.0"
rusoto_core = "0.43.0"
tokio = { version = "0.2.21", features = ["macros"] }
futures = "0.3.5"

Answer 2

您快到了。您的代码会将对象放入if error != nil { ProgressHUD.showError(error!.localizedDescription) return } if let photoUrl = metadata?.downloadURL()?.absoluteString { onSuccess(photoUrl) } } } static func sendDataToDatabase(photoUrl: String, videoUrl: String? = nil, ratio: CGFloat, caption: String, onSuccess: @escaping () -> Void) { let newPostId = Api.Post.REF_POSTS.childByAutoId().key let newPostReference = Api.Post.REF_POSTS.child(newPostId) guard let currentUser = Api.User.CURRENT_USER else { return } let words = caption.components(separatedBy: CharacterSet.whitespacesAndNewlines) for var word in words { if word.hasPrefix("#") { word = word.trimmingCharacters(in: CharacterSet.punctuationCharacters) word = word.trimmingCharacters(in: CharacterSet.symbols) let newHashReference = Api.HashTag.REF_HASHTAG.child(word.lowercased()) newHashReference.setValue([newPostId: true]) // let hashTagsRef = DataService.dataService.BASE_REF.child("hashTags").child(postKey) // let data = ["to": "", "by": "\(DataService.dataService.currentUserId!)", "hashTag": word.lowercased(), "comment": self.captionTextView.text] as [String : Any] // hashTagsRef.setValue(data) } } let currentUserId = currentUser.id var dict = ["id": currentUserId! ,"photoUrl": photoUrl, "caption": caption, "likeCount": 0, "ratio": ratio] as [String : Any] if let videoUrl = videoUrl { dict["videoUrl"] = videoUrl } newPostReference.setValue(dict, withCompletionBlock: { (error, ref) in if error != nil { ProgressHUD.showError(error!.localizedDescription) return } Api.Feed.REF_FEED.child(Api.User.CURRENT_USER!.id!).child(newPostId).setValue(true) let myPostRef = Api.MyPosts.REF_MYPOSTS.child(currentUserId!).child(newPostId) myPostRef.setValue(true, withCompletionBlock: { (error, ref) in if error != nil { ProgressHUD.showError(error!.localizedDescription) return } }) ProgressHUD.showSuccess("Success") onSuccess() }) } }中的body中。

要将Vec<u8>的内容写入文件：

body

如何将使用Rusoto从S3下载的文件保存到我的硬盘上？

2 个答案:

读取内存

流式传输文件

依赖版本