Amazon S3签名不匹配 - AWS SDK Java

我有一个需要将文件上传到S3的播放应用程序.我们正在使用Scala开发并使用Java AWS SDK.

我在尝试上传文件时遇到问题,在使用预先签名的网址时,我一直收到403 SignatureDoesNotMatch.使用AWS Java SDK通过以下代码生成URL:

def generatePresignedPutRequest(filename: String) = {
    val expiration = new java.util.Date();
    var msec = expiration.getTime() + 1000 * 60 * 60; // Add 1 hour.
    expiration.setTime(msec);

    s3 match {
      case Some(s3) => s3.generatePresignedUrl(bucketname, filename, expiration, HttpMethod.PUT).toString
      case None => {
        Logger.warn("S3 is not availiable. Cannot generate PUT request.")
        "URL not availiable"
      }
    }
  }

对于前端代码,我们遵循ioncannon文章.

上传文件的js函数(与文章中使用的相同)

 function uploadToS3(file, url)
     {
       var xhr = createCORSRequest('PUT', url);
       if (!xhr) 
       {
         setProgress(0, 'CORS not supported');
       }
       else
       {
         xhr.onload = function() 
         {
           if(xhr.status == 200)
           {
             setProgress(100, 'Upload completed.');
           }
           else
           {
             setProgress(0, 'Upload error: ' + xhr.status);
           }
         };

         xhr.onerror = function() 
         {
           setProgress(0, 'XHR error.');
         };

         xhr.upload.onprogress = function(e) 
         {
           if (e.lengthComputable) 
           {
             var percentLoaded = Math.round((e.loaded / e.total) * 100);
             setProgress(percentLoaded, percentLoaded == 100 ? 'Finalizing.' : 'Uploading.');
           }
         };

         xhr.setRequestHeader('Content-Type', 'image/png');
         xhr.setRequestHeader('x-amz-acl', 'authenticated-read');

         xhr.send(file);
       }
     }

服务器的响应是

SignatureDoesNotMatch
The request signature we calculated does not match the signature you provided. Check your key and signing method.
50 55 bla bla bla...
F7A8F1659DE5909C
q+r+2T5K6mWHLKTZw0R9/jm22LyIfZFBTY8GEDznfmJwRxvaVJwPiu/hzUfuJWbW
PUT

    image/png
    1387565829
    x-amz-acl:authenticated-read
    /mybucketname/icons/f5430c16-32da-4315-837f-39a6cf9f47a1
myaccesskey

我已经配置了CORS,双重检查了aws凭据并尝试更改请求标头.我总是得到相同的结果.亚马逊为什么告诉我签名不匹配？