Javascript 上传文件到Azure存储

时间 2019-11-18

标签 javascript 上传文件 azure 存储栏目 JavaScript 繁體版

原文原文链接

对一些前端工程师来说，使用javascript上传文件到Azure存储中多是须要掌握的技能，但愿这篇博客能给到帮助。javascript

在开始前咱们须要了解如下几点：html

共享访问签名jquery

共享访问签名，是用于提供对Windows Azure Storage中的Container，Blob，Table以及Queue在特定时间范围内进行有限权限访问的URL。一般状况下，咱们访问Azure存储都是以帐户名和密码的方式来实现的，经过这种方式也给使用者包括增删改在内的最大的访问权限，可是在实际状况中，咱们可能但愿用户只有读的权限，同时咱们也不但愿将帐户名和密码泄露出去，共享访问签名很好的解决了这类问题。咱们在使用Javascript上传时就是经过共享访问签名的URL来进行的。ajax

Azure 存储服务的跨域资源共享 (CORS) 支持编程

大概在2014年3月份的时候Azure已经支持CORS，通过测试目前中国版和国际版都已经支持，咱们在使用Javascript上传的时候是将资源以PUT的方式上传到相似于http://***.blob.core.chinacloudapi.cn这样域名的地方，这就涉及到CORS的问题，在默认状况下Azure存储是禁用CORS的，因此咱们须要使用版本 2013-08-15 或更高版本设置适当的服务属性，并向服务属性中添加 CORS 规则，若是咱们没有启用CORS规则，咱们可能会获得403错误，使用Fiddler工具会获得更详细的错误信息：”CORS not enabled or no matching rule found for this request”。windows

经过上面的描述，咱们在开始编程前，咱们须要SAS URL，还须要为咱们的blob配置CORS规则，这些咱们能够经过Azure SDK来实现，关于这部分我就不介绍了，详细请阅读：#SAS:http://www.windowsazure.cn/zh-cn/documentation/articles/storage-dotnet-shared-access-signature-part-2/api

#CORS:http://blogs.msdn.com/b/windowsazurestorage/archive/2014/02/03/windows-azure-storage-introducing-cors.aspx跨域

若是咱们不太了解C#，咱们能够借助Azure Storage Explorer来进行配置，下面我介绍下简单的配置:

1）获得SAS URL

打开Azure Storage Explorer点击“Security”，选择SAS失效的时间，并选择赋予相应的权限，如上图高亮标注的部分。

2）配置CORS规则

打开Azure Storage Explorer鼠标停留在”Blob Containers”，这时会出现CORS设置按钮，点击新增CORS规则，并如上图设置，关于具体的设置信息，请阅读：https://msdn.microsoft.com/zh-cn/library/azure/dn535601.aspx?f=255&MSPPError=-2147217396，图中的设置是我测试的字段，可做为参考。

下面是具体的代码

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">

<head>

    <title>File Uploader</title>

 

    <script src="Scripts/jquery-1.10.2.min.js"></script>

 

    <script>

        var maxBlockSize = 256 * 1024;//Each file will   be split in 256 KB.

        var numberOfBlocks = 1;

        var selectedFile = null;

        var currentFilePointer = 0;

        var totalBytesRemaining = 0;

        var blockIds = new Array();

        var blockIdPrefix = "block-";

        var submitUri = null;

        var bytesUploaded = 0;

 

        $(document).ready(function () {

            $("#output").hide();

            $("#file").bind('change',   handleFileSelect);

            if (window.File &&   window.FileReader && window.FileList && window.Blob) {

                // Great success!   All the File APIs are supported.

            } else {

                alert('The File APIs are   not fully supported in this browser.');

            }

        });

 

        //Read the file and find out how   many blocks we would need to split it.

        function handleFileSelect(e) {

            maxBlockSize = 256 *   1024;

            currentFilePointer =   0;

            totalBytesRemaining =   0;

            var files = e.target.files;

            selectedFile =   files[0];

            $("#output").show();

            $("#fileName").text(selectedFile.name);

            $("#fileSize").text(selectedFile.size);

            $("#fileType").text(selectedFile.type);

            var fileSize = selectedFile.size;

            if (fileSize < maxBlockSize) {

                maxBlockSize =   fileSize;

                console.log("max block   size = " +   maxBlockSize);

            }

            totalBytesRemaining =   fileSize;

            if (fileSize % maxBlockSize == 0) {

                numberOfBlocks =   fileSize / maxBlockSize;

            } else {

                numberOfBlocks =   parseInt(fileSize / maxBlockSize, 10) + 1;

            }

            console.log("total blocks   = " +   numberOfBlocks);

            var baseUrl = $("#sasUrl").val();

            var indexOfQueryStart = baseUrl.indexOf("?");

            submitUri =   baseUrl.substring(0, indexOfQueryStart) + '/' + selectedFile.name +   baseUrl.substring(indexOfQueryStart);

              console.log(submitUri);

        }

 

        var reader = new FileReader();

 

        reader.onloadend = function (evt) {

            if (evt.target.readyState ==   FileReader.DONE) { // DONE == 2

                var uri = submitUri + '&comp=block&blockid=' +   blockIds[blockIds.length - 1];

                var requestData = new Uint8Array(evt.target.result);

                $.ajax({

                    url: uri,

                    type: "PUT",

                    data:   requestData,

                    processData: false,

                    beforeSend: function (xhr) {

                        xhr.setRequestHeader('x-ms-blob-type', 'BlockBlob');

                          xhr.setRequestHeader('Content-Length', requestData.length);

                    },

                    success: function (data, status) {

                          console.log(data);

                          console.log(status);

                          bytesUploaded += requestData.length;

                        var percentComplete =   ((parseFloat(bytesUploaded) / parseFloat(selectedFile.size)) *   100).toFixed(2);

                        $("#fileUploadProgress").text(percentComplete   + "   %");

                          uploadFileInBlocks();

                    },

                    error: function (xhr, desc, err)   {

                          console.log(desc);

                          console.log(err);

                    }

                });

            }

        };

 

        function uploadFileInBlocks() {

            if (totalBytesRemaining > 0) {

                console.log("current file   pointer = " + currentFilePointer + " bytes read = " + maxBlockSize);

                var fileContent =   selectedFile.slice(currentFilePointer, currentFilePointer + maxBlockSize);

                var blockId = blockIdPrefix +   pad(blockIds.length, 6);

                console.log("block id =   " +   blockId);

                  blockIds.push(btoa(blockId));

                  reader.readAsArrayBuffer(fileContent);

                currentFilePointer   += maxBlockSize;

                  totalBytesRemaining -= maxBlockSize;

                if (totalBytesRemaining <   maxBlockSize) {

                    maxBlockSize =   totalBytesRemaining;

                }

            } else {

                commitBlockList();

            }

        }

 

        function commitBlockList() {

            var uri = submitUri + '&comp=blocklist';

            console.log(uri);

            var requestBody = '<?xml   version="1.0" encoding="utf-8"?><BlockList>';

            for (var i = 0; i < blockIds.length;   i++) {

                requestBody += '<Latest>' + blockIds[i] + '</Latest>';

            }

            requestBody += '</BlockList>';

              console.log(requestBody);

            $.ajax({

                url: uri,

                type: "PUT",

                data: requestBody,

                beforeSend: function (xhr) {

                      xhr.setRequestHeader('x-ms-blob-content-type', selectedFile.type);

                      xhr.setRequestHeader('Content-Length', requestBody.length);

                },

                success: function (data, status) {

                    console.log(data);

                      console.log(status);

                },

                error: function (xhr, desc, err)   {

                      console.log(desc);

                      console.log(err);

                }

            });

 

        }

        function pad(number, length) {

            var str = '' + number;

            while (str.length < length) {

                str = '0' + str;

            }

            return str;

        }

    </script>

</head>

<body>

    <form>

        <div style="margin-left: 20px;">

            <h1>File Uploader</h1>

            <p>

                <strong>SAS URI</strong>:

                <br />

                <span class="input-control text">

                    <input type="text" id="sasUrl" style="width: 50%"

                           value="" />

                </span>

            </p>

            <p>

                <strong>File To Upload</strong>:

                <br />

                <span class="input-control text">

                    <input type="file" id="file" name="file" style="width: 50%" />

                </span>

            </p>

            <div id="output">

 

                <strong>File Properties:</strong>

                <br />

                <p>

                    Name: <span id="fileName"></span>

                </p>

                <p>

                    File Size: <span id="fileSize"></span> bytes.

                </p>

                <p>

                    File Type: <span id="fileType"></span>

                </p>

                <p>

                    <input type="button" value="Upload File" onclick="uploadFileInBlocks()" />

                </p>

                <p>

                    <strong>Progress</strong>: <span id="fileUploadProgress">0.00 %</span>

                </p>

            </div>

        </div>

        <div>

        </div>

    </form>

</body>

</html>

View Code

代码主要是将文件切成小块，并使用Put blob操做上传相应的小块，最后使用Put blob list将上传的各个小块组成资源文件。