将图像和视频上传到（S3，CloudFront等）的服务

Question

我正在寻找一项服务来从我的移动应用程序（前端）上传视频和图像。我听说过Amazon S3和CloudFront。我正在寻找将存储它们的服务，并且还能够检查它们是否符合特定条件（例如，每张图片的最大文件大小为3MB），并且如果文件不符合，则会向客户端返回错误标准。 Amazon S3或CloudFront是否提供此功能？如果没有，有没有其他推荐的服务呢？

Answer 1

您可以使用AWS开发工具包。这里如下（Amazon提供的SDK不同语言）的Java版本为例：

/** 
* It stores the given file name in S3 and returns the key under which the file has been stored 
* @param resource 
* @param bucketName 
* @return 
*/ 
public String storeProfileImage(File resource, String bucketName, String username) { 

    String resourceUrl = null; 

    if (!resource.exists()) { 
     throw new IllegalArgumentException("The file " + resource.getAbsolutePath() + " doesn't exist"); 

    } 

    long lengthInBytes = resource.length(); 

    //For demo purposes. You should use a configurable property for the max size 
    if (lengthInBytes > (3 * 1024)) { 
     //Your error handling here 
    } 

    AccessControlList acl = new AccessControlList(); 
    acl.grantPermission(GroupGrantee.AllUsers, Permission.Read); 

    String key = username + "/profilePicture." + FilenameUtils.getExtension(resource.getName()); 

    try { 
     s3Client.putObject(new PutObjectRequest(bucketName, key, resource).withAccessControlList(acl)); 
     resourceUrl = s3Client.getResourceUrl(bucketName, key); 
    } catch (AmazonClientException ace) { 
     LOG.error("A client exception occurred while trying to store the profile" + 
       " image {} on S3. The profile image won't be stored", resource.getAbsolutePath(), ace); 
    } 

    return resourceUrl; 

} 

您也可以执行其它操作，例如在存储图像之前检查存储桶是否存在

/** 
* Returns the root URL where the bucket name is located. 
* <p>Please note that the URL does not contain the bucket name</p> 
* @param bucketName The bucket name 
* @return the root URL where the bucket name is located. 
*/ 
public String ensureBucketExists(String bucketName) { 

    String bucketUrl = null; 

    try { 
     if (!s3Client.doesBucketExist(bucketName)) { 
      LOG.warn("Bucket {} doesn't exists...Creating one"); 
      s3Client.createBucket(bucketName); 
      LOG.info("Created bucket: {}", bucketName); 
     } 
     bucketUrl = s3Client.getResourceUrl(bucketName, null) + bucketName; 
    } catch (AmazonClientException ace) { 
     LOG.error("An error occurred while connecting to S3. Will not execute action" + 
       " for bucket: {}", bucketName, ace); 
    } 


    return bucketUrl; 
}