创建使用的Windows Azure Blob存储缩略图

本文介绍了创建使用的Windows Azure Blob存储缩略图的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我试图使用Azure的SDK换节点到流图像保存到Windows Azure Blob存储，但没有成功。下面是我打电话和缩略图财产传视频对象的函数。起初，我用获取从其他网站获取的图像，并把它转换成这反过来又被转换成流对象一个base64对象，因为Azure的BLOB服务使用createBlockBlobFromStream方法，我不能使用createBlockBlobFromFile或createBlockBlobFromText上传请求对象的图像图像以Blob存储。

I am trying to use the azure-sdk-for-node to save a streamed image to Windows Azure blob storage but without success. Below is the function that I call and pass the video object with the thumbnail property. Initially I fetch the image using the request object which fetches the image from another website and turn that into a base64 object which in turn gets converted into a stream object because Azure blob service uses createBlockBlobFromStream method as I couldn't use createBlockBlobFromFile or createBlockBlobFromText to upload the image to blob storage.

var azure = require('azure')
    , uuid = require('node-uuid')
    , http = require('http')
    , url = require('url')
    , mmm = require('mmmagic')
    , Magic = mmm.Magic
    , stream = require('stream');

function createVideoThumbnail(video, callback){
    var bs = azure.createBlobService(config.storageAccount, config.storageAccessKey, config.blobHost);
    var sURL = video.Thumbnail;
    var oURL = url.parse(sURL);
    var client = http.createClient(80, oURL.hostname);
    var request = client.request('GET', oURL.pathname, {'host': oURL.hostname});

    request.end();
    request.on('response', function (response) {
        var type = response.headers["content-type"];
        var prefix = "data:" + type + ";base64,";
        var body = "";

        response.setEncoding('binary');
        response.on('end', function () {
            var base64 = new Buffer(body, 'binary').toString('base64');
            var data = prefix + base64;
            console.log('base64 image data ' + video.Thumbnail + ': ' + data + '\n');

            var decodedImage = new Buffer(data, 'base64');
            var magic = new Magic(mmm.MAGIC_MIME_TYPE);

            magic.detect(decodedImage, function(err, result) {
                if(err) {
                    throw err;
                }

                var bytes = 0;
                var imageStream = new stream.Stream();
                imageStream.writable = true;

                imageStream.write = function(buf) {
                    bytes += buf.length;
                    imageStream.emit('data', buf);
                };

                imageStream.end = function(buf) {
                    //if(arguments.length) {
                        imageStream.write(buf);
                    //}

                    imageStream.writable = false;
                    imageStream.emit('end');
                    console.log(bytes + ' bytes written');
                };

                var options = {}
                console.log('mmm = ' + result + '\n');
                options.contentType = result;
                options.contentTypeHeader = result;

                console.log('\n');
                bs.createBlockBlobFromStream(config.imageContainer, uuid().replace(/-/gi, "").toLowerCase() + '.jpg', imageStream, decodedImage.length, options, function(error, blobResult, response) {
                    if (error)
                        console.log('got error = ' + JSON.stringify(error) + '\n');

                    if (blobResult)
                        console.log('blobResult = ' + JSON.stringify(blobResult) + '\n');

                    if (response)
                        console.log('response = ' + JSON.stringify(response) + '\n');

                    // now store in Azure blob storage
                    callback();
                });

                imageStream.end(decodedImage);
            });
        });
        response.on('data', function (chunk) {
            if (response.statusCode == 200) body += chunk;
        });
    });
}

这就是我怎么称呼它：

and this is how I call it:

createVideoThumbnail(video, function(){
    console.log("returning from create thumbnails\n\n");
});

该功能无法正常工作搞得晕头转向，不会打印出来的，最终的日志语句：

The function is not working it hangs and won't print out the the final log statement:

console.log("returning from create thumbnails\n\n");

然而以base64似乎因为我得到这个的编码工作：

However the base64 does seem to work as I am getting this for the encoding:

MMM =应用程序/八位字节流
书面5283字节

mmm = application/octet-stream5283 bytes written

但我没有得到任何这些日志报表正在打印：

But I am not getting any of these log statements being printed:

if (error)
    console.log('got error = ' + JSON.stringify(error) + '\n');

if (blobResult)
    console.log('blobResult = ' + JSON.stringify(blobResult) + '\n');

if (response)
    console.log('response = ' + JSON.stringify(response) + '\n');

所以我presuming它挂的地方还是我没有结构性我的code正确。任何人都可以看到我在做什么错了？

So I am presuming it is hanging somewhere or I have not structured my code properly. Can anybody see what I am doing wrong ?

干杯
罗布

我的消息来源：

http://social.msdn.microsoft.com/Forums/en-US/wavirtualmachinesforlinux/thread/47bfe142-c459-4815-b09e-bd0a07ca18d5

<一个href=\"http://stackoverflow.com/questions/3709391/node-js-base64-en$c$c-a-downloaded-image-for-use-in-data-uri\">Node.js连接的base64 code在数据使用下载的图像URI

createBlockBlobFromStream

创建使用的Windows Azure Blob存储缩略图

问题描述

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