微信小程序环境下将文件上传到 OSS

accessid= '';
accesskey= '';
host = '';

g_dirname = ''
g_object_name = ''
g_object_name_type = ''
now = timestamp = Date.parse(new Date()) / 1000; 

var policyText = {
    "expiration": "2020-01-01T12:00:00.000Z", //设置该Policy的失效时间，超过这个失效时间之后，就没有办法通过这个policy上传文件了
    "conditions": [
    ["content-length-range", 0, 1048576000] // 设置上传文件的大小限制
    ]
};

var policyBase64 = Base64.encode(JSON.stringify(policyText))
message = policyBase64
var bytes = Crypto.HMAC(Crypto.SHA1, message, accesskey, { asBytes: true }) ;
var signature = Crypto.util.bytesToBase64(bytes);

function check_object_radio() {
    var tt = document.getElementsByName('myradio');
    for (var i = 0; i < tt.length ; i++ )
    {
        if(tt[i].checked)
        {
            g_object_name_type = tt[i].value;
            break;
        }
    }
}

function get_dirname()
{
    dir = document.getElementById("dirname").value;
    if (dir != '' && dir.indexOf('/') != dir.length - 1)
    {
        dir = dir + '/'
    }
    //alert(dir)
    g_dirname = dir
}

function random_string(len) {
　　len = len || 32;
　　var chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678';   
　　var maxPos = chars.length;
　　var pwd = '';
　　for (i = 0; i < len; i++) {
    　　pwd += chars.charAt(Math.floor(Math.random() * maxPos));
    }
    return pwd;
}

function get_suffix(filename) {
    pos = filename.lastIndexOf('.')
    suffix = ''
    if (pos != -1) {
        suffix = filename.substring(pos)
    }
    return suffix;
}

function calculate_object_name(filename)
{
    if (g_object_name_type == 'local_name')
    {
        g_object_name += "${filename}"
    }
    else if (g_object_name_type == 'random_name')
    {
        suffix = get_suffix(filename)
        g_object_name = g_dirname + random_string(10) + suffix
    }
    return ''
}

function get_uploaded_object_name(filename)
{
    if (g_object_name_type == 'local_name')
    {
        tmp_name = g_object_name
        tmp_name = tmp_name.replace("${filename}", filename);
        return tmp_name
    }
    else if(g_object_name_type == 'random_name')
    {
        return g_object_name
    }
}

function set_upload_param(up, filename, ret)
{
    g_object_name = g_dirname;
    if (filename != '') {
        suffix = get_suffix(filename)
        calculate_object_name(filename)
    }
    new_multipart_params = {
        'key' : g_object_name,
        'policy': policyBase64,
        'OSSAccessKeyId': accessid, 
        'success_action_status' : '200', //让服务端返回200,不然，默认会返回204
        'signature': signature,
    };

    up.setOption({
        'url': host,
        'multipart_params': new_multipart_params
    });

    up.start();
}

var uploader = new plupload.Uploader({
    runtimes : 'html5,flash,silverlight,html4',
    browse_button : 'selectfiles', 
    //multi_selection: false,
    container: document.getElementById('container'),
    flash_swf_url : 'lib/plupload-2.1.2/js/Moxie.swf',
    silverlight_xap_url : 'lib/plupload-2.1.2/js/Moxie.xap',
    url : 'http://oss.aliyuncs.com',

    init: {
        PostInit: function() {
            document.getElementById('ossfile').innerHTML = '';
            document.getElementById('postfiles').onclick = function() {
            set_upload_param(uploader, '', false);
            return false;
            };
        },

        FilesAdded: function(up, files) {
            plupload.each(files, function(file) {
                document.getElementById('ossfile').innerHTML += '<div id="' + file.id + '">' + file.name + ' (' + plupload.formatSize(file.size) + ')<b></b>'
                +'<div class="progress"><div class="progress-bar" style="width: 0%"></div></div>'
                +'</div>';
            });
        },

        BeforeUpload: function(up, file) {
            check_object_radio();
            get_dirname();
            set_upload_param(up, file.name, true);
        },

        UploadProgress: function(up, file) {
            var d = document.getElementById(file.id);
            d.getElementsByTagName('b')[0].innerHTML = '<span>' + file.percent + "%</span>";
            var prog = d.getElementsByTagName('div')[0];
            var progBar = prog.getElementsByTagName('div')[0]
            progBar.style.width= 2*file.percent+'px';
            progBar.setAttribute('aria-valuenow', file.percent);
        },

        FileUploaded: function(up, file, info) {
            if (info.status == 200)
            {
                document.getElementById(file.id).getElementsByTagName('b')[0].innerHTML = 'upload to oss success, object name:' + get_uploaded_object_name(file.name);
            }
            else
            {
                document.getElementById(file.id).getElementsByTagName('b')[0].innerHTML = info.response;
            } 
        },

        Error: function(up, err) {
            document.getElementById('console').appendChild(document.createTextNode("\nError xml:" + err.response));
        }
    }
});

uploader.init();

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8"/>
    <title>OSS web直传</title>
    <link rel="stylesheet" type="text/css" href="style.css"/>
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
</head>
<body>

<h2>OSS web直传---直接在JS签名</h2>
<ol>
<li>基于plupload封装 </li>
<li>支持html5,flash,silverlight,html4 等协议上传</li>
<li>可以运行在PC浏览器，手机浏览器，微信</li>
<li>可以选择多文件上传</li>
<li>显示上传进度条</li>
<li>可以控制上传文件的大小</li>
<li>最关键的是，让你10分钟之内就能移植到你的系统，实现以上牛逼的功能！</li>
<li>注意一点，bucket必须设置了Cors(Post打勾）,不然没有办法上传</li>
<li>注意一点，把upload.js 里面的host/accessid/accesskey改成您上传所需要的信息即可</li>
<li>此方法是直接在前端签名，有accessid/accesskey泄漏的风险, 线上生产请使用后端签名例子<a href="https://help.aliyun.com/document_detail/oss/practice/pc_web_upload/js_php_upload.html">点击查看详细文档</a></li>
</ol>
<br>
<form name=theform>
<input type="radio" name="myradio" value="local_name" checked=true/> 上传文件名字保持本地文件名字
<input type="radio" name="myradio" value="random_name" /> 上传文件名字是随机文件名
<br/>
上传到指定目录:<input type="text" id='dirname' placeholder="如果不填，默认是上传到根目录" size=50>
</form>

<h4>您所选择的文件列表：</h4>
<div id="ossfile">你的浏览器不支持flash,Silverlight或者HTML5！</div>

<br/>

<div id="container">
    <a id="selectfiles" href="javascript:void(0);" class='btn'>选择文件</a>
    <a id="postfiles" href="javascript:void(0);" class='btn'>开始上传</a>
</div>

<pre id="console"></pre>

<p>&nbsp;</p>

</body>
<script type="text/javascript" src="lib/crypto1/crypto/crypto.js"></script>
<script type="text/javascript" src="lib/crypto1/hmac/hmac.js"></script>
<script type="text/javascript" src="lib/crypto1/sha1/sha1.js"></script>
<script type="text/javascript" src="lib/base64.js"></script>
<script type="text/javascript" src="lib/plupload-2.1.2/js/plupload.full.min.js"></script>
<script type="text/javascript" src="upload.js"></script>
</html>

this.$navigate({url:"content"})

this.$parent.$navigate({url:"content"})

wepy.navigateTo({
url: '/pages/content'
})