AmazonS3 putObject与InputStream长度的例子

Question

我正在使用Java将文件上传到S3 - 这是我到目前为止所得到的:

AmazonS3 s3 = new AmazonS3Client(new BasicAWSCredentials("XX","YY"));

List<Bucket> buckets = s3.listBuckets();

s3.putObject(new PutObjectRequest(buckets.get(0).getName(), fileName, stream, new ObjectMetadata()));

正在上传文件,但在我未设置内容长度时会引发警告:

com.amazonaws.services.s3.AmazonS3Client putObject: No content length specified for stream > data.  Stream contents will be buffered in memory and could result in out of memory errors.

这是我上传的文件,stream变量是一个InputStream,我可以从中得到这样的字节数组:IOUtils.toByteArray(stream).

所以,当我尝试设置内容长度和MD5(从这里取得)像这样:

// get MD5 base64 hash
MessageDigest messageDigest = MessageDigest.getInstance("MD5");
messageDigest.reset();
messageDigest.update(IOUtils.toByteArray(stream));
byte[] resultByte = messageDigest.digest();
String hashtext = new String(Hex.encodeHex(resultByte));

ObjectMetadata meta = new ObjectMetadata();
meta.setContentLength(IOUtils.toByteArray(stream).length);
meta.setContentMD5(hashtext);

它会导致以下错误从S3返回:

您指定的Content-MD5无效.

我究竟做错了什么？

任何帮助赞赏!

PS我在Google App Engine上 - 我无法将文件写入磁盘或创建临时文件,因为AppEngine不支持FileOutputStream.

Answer 1

因为原始问题从未得到解答,我不得不遇到同样的问题,MD5问题的解决方案是S3不想要我们通常想到的Hex编码的MD5字符串.

相反,我必须这样做.

// content is a passed in InputStream
byte[] resultByte = DigestUtils.md5(content);
String streamMD5 = new String(Base64.encodeBase64(resultByte));
metaData.setContentMD5(streamMD5);

基本上他们想要的MD5值是Base64编码的原始MD5字节数组,而不是Hex字符串.当我切换到这个时,它开始为我工作.

Answer 2

如果您要做的就是解决亚马逊的内容长度错误,那么您只需将输入流中的字节读取到Long并将其添加到元数据中.

/*
 * Obtain the Content length of the Input stream for S3 header
 */
try {
    InputStream is = event.getFile().getInputstream();
    contentBytes = IOUtils.toByteArray(is);
} catch (IOException e) {
    System.err.printf("Failed while reading bytes from %s", e.getMessage());
} 

Long contentLength = Long.valueOf(contentBytes.length);

ObjectMetadata metadata = new ObjectMetadata();
metadata.setContentLength(contentLength);

/*
 * Reobtain the tmp uploaded file as input stream
 */
InputStream inputStream = event.getFile().getInputstream();

/*
 * Put the object in S3
 */
try {

    s3client.putObject(new PutObjectRequest(bucketName, keyName, inputStream, metadata));

} catch (AmazonServiceException ase) {
    System.out.println("Error Message:    " + ase.getMessage());
    System.out.println("HTTP Status Code: " + ase.getStatusCode());
    System.out.println("AWS Error Code:   " + ase.getErrorCode());
    System.out.println("Error Type:       " + ase.getErrorType());
    System.out.println("Request ID:       " + ase.getRequestId());
} catch (AmazonClientException ace) {
    System.out.println("Error Message: " + ace.getMessage());
} finally {
    if (inputStream != null) {
        inputStream.close();
    }
}

您需要使用这种精确的方法读取输入流两次,因此如果您要上传一个非常大的文件,您可能需要先将其读入数组,然后从那里读取它.

Answer 3

对于上传,S3 SDK有两个putObject方法:

PutObjectRequest(String bucketName, String key, File file)

和

PutObjectRequest(String bucketName, String key, InputStream input, ObjectMetadata metadata)

inputstream + ObjectMetadata方法需要输入流的Content Length的最小元数据.如果不这样做,那么它将在内存中缓冲以获取该信息,这可能会导致OOM.或者,您可以使用自己的内存缓冲来获取长度,但是您需要获得第二个输入流.

OP没有提出要求(他的环境有限),但是对于其他人,比如我.我发现它更容易,更安全(如果你有权访问临时文件),将输入流写入临时文件,并放入临时文件.没有内存缓冲区,也没有要求创建第二个输入流.

AmazonS3 s3Service = new AmazonS3Client(awsCredentials);
File scratchFile = File.createTempFile("prefix", "suffix");
try {
    FileUtils.copyInputStreamToFile(inputStream, scratchFile);    
    PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, id, scratchFile);
    PutObjectResult putObjectResult = s3Service.putObject(putObjectRequest);

} finally {
    if(scratchFile.exists()) {
        scratchFile.delete();
    }
}

Answer 4

写入S3时,需要指定S3对象的长度,以确保没有内存不足错误.

使用IOUtils.toByteArray(stream)也容易出现OOM错误,因为这是由ByteArrayOutputStream支持的

因此,最好的选择是首先将输入流写入本地磁盘上的临时文件,然后通过指定临时文件的长度使用该文件写入S3.

Answer 5

我实际上在做一些相同的事情，但是在我的AWS S3存储上：-

正在接收上传文件的servlet的代码：-

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.src.code.s3.S3FileUploader;

public class FileUploadHandler extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();

        try{
            List<FileItem> multipartfiledata = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);

            //upload to S3
            S3FileUploader s3 = new S3FileUploader();
            String result = s3.fileUploader(multipartfiledata);

            out.print(result);
        } catch(Exception e){
            System.out.println(e.getMessage());
        }
    }
}

将数据作为AWS对象上传的代码：-

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.List;
import java.util.UUID;

import org.apache.commons.fileupload.FileItem;

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.ClasspathPropertiesFileCredentialsProvider;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3Client;
import com.amazonaws.services.s3.model.ObjectMetadata;
import com.amazonaws.services.s3.model.PutObjectRequest;
import com.amazonaws.services.s3.model.S3Object;

public class S3FileUploader {


    private static String bucketName     = "***NAME OF YOUR BUCKET***";
    private static String keyName        = "Object-"+UUID.randomUUID();

    public String fileUploader(List<FileItem> fileData) throws IOException {
        AmazonS3 s3 = new AmazonS3Client(new ClasspathPropertiesFileCredentialsProvider());
        String result = "Upload unsuccessfull because ";
        try {

            S3Object s3Object = new S3Object();

            ObjectMetadata omd = new ObjectMetadata();
            omd.setContentType(fileData.get(0).getContentType());
            omd.setContentLength(fileData.get(0).getSize());
            omd.setHeader("filename", fileData.get(0).getName());

            ByteArrayInputStream bis = new ByteArrayInputStream(fileData.get(0).get());

            s3Object.setObjectContent(bis);
            s3.putObject(new PutObjectRequest(bucketName, keyName, bis, omd));
            s3Object.close();

            result = "Uploaded Successfully.";
        } catch (AmazonServiceException ase) {
           System.out.println("Caught an AmazonServiceException, which means your request made it to Amazon S3, but was "
                + "rejected with an error response for some reason.");

           System.out.println("Error Message:    " + ase.getMessage());
           System.out.println("HTTP Status Code: " + ase.getStatusCode());
           System.out.println("AWS Error Code:   " + ase.getErrorCode());
           System.out.println("Error Type:       " + ase.getErrorType());
           System.out.println("Request ID:       " + ase.getRequestId());

           result = result + ase.getMessage();
        } catch (AmazonClientException ace) {
           System.out.println("Caught an AmazonClientException, which means the client encountered an internal error while "
                + "trying to communicate with S3, such as not being able to access the network.");

           result = result + ace.getMessage();
         }catch (Exception e) {
             result = result + e.getMessage();
       }

        return result;
    }
}

注意：-我正在使用aws属性文件获取凭据。

希望这可以帮助。