Question

我正在尝试通过javascript上传pdf文件。我有该文件的base64表示，我解码它。文件已上传，但该数据似乎已损坏。

当我尝试打开文件时，错误消息显示“文件已损坏且无法修复”。

我得到了base64字符串服务器端...

byte[] buffer = new byte[length];  
var postedFile = httpRequest.Files[file];                 
postedFile.InputStream.Read(buffer, 0, length);
string encodedString = Convert.ToBase64String(buffer);

这是我上传文件的ajax调用

var data= Base64.decode(result); //result is the base64 encoded string
 $.ajax({
                    url: url,
                    type: "POST",
                    data: data,
                    processData: false,
                    headers: {
                        "accept": "application/json;odata=verbose",
                        "X-RequestDigest": _digetsValue,
                        "content-length": length

                    },
                    success: function (data)
                    {
                        alert("it worked");

                    },
                    error: function (err)
                    {

                    }
                });

对于解码，我正在使用这段代码...... 或者从这里How can you encode a string to Base64 in JavaScript?

var Base64 = {
        // private property
        _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

        // public method for encoding
        encode: function (input)
        {
            var output = "";
            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
            var i = 0;

            input = Base64._utf8_encode(input);

            while (i < input.length)
            {

                chr1 = input.charCodeAt(i++);
                chr2 = input.charCodeAt(i++);
                chr3 = input.charCodeAt(i++);

                enc1 = chr1 >> 2;
                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
                enc4 = chr3 & 63;

                if (isNaN(chr2))
                {
                    enc3 = enc4 = 64;
                } else if (isNaN(chr3))
                {
                    enc4 = 64;
                }

                output = output +
                Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) +
                Base64._keyStr.charAt(enc3) + Base64._keyStr.charAt(enc4);

            }

            return output;
        },

        // public method for decoding
        decode: function (input)
        {
            var output = "";
            var chr1, chr2, chr3;
            var enc1, enc2, enc3, enc4;
            var i = 0;

            input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

            while (i < input.length)
            {

                enc1 = Base64._keyStr.indexOf(input.charAt(i++));
                enc2 = Base64._keyStr.indexOf(input.charAt(i++));
                enc3 = Base64._keyStr.indexOf(input.charAt(i++));
                enc4 = Base64._keyStr.indexOf(input.charAt(i++));

                chr1 = (enc1 << 2) | (enc2 >> 4);
                chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
                chr3 = ((enc3 & 3) << 6) | enc4;

                output = output + String.fromCharCode(chr1);

                if (enc3 != 64)
                {
                    output = output + String.fromCharCode(chr2);
                }
                if (enc4 != 64)
                {
                    output = output + String.fromCharCode(chr3);
                }

            }

            output = Base64._utf8_decode(output);

            return output;

        },

        // private method for UTF-8 encoding
        _utf8_encode: function (string)
        {
            string = string.replace(/\r\n/g, "\n");
            var utftext = "";

            for (var n = 0; n < string.length; n++)
            {

                var c = string.charCodeAt(n);

                if (c < 128)
                {
                    utftext += String.fromCharCode(c);
                }
                else if ((c > 127) && (c < 2048))
                {
                    utftext += String.fromCharCode((c >> 6) | 192);
                    utftext += String.fromCharCode((c & 63) | 128);
                }
                else
                {
                    utftext += String.fromCharCode((c >> 12) | 224);
                    utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                    utftext += String.fromCharCode((c & 63) | 128);
                }

            }

            return utftext;
        },

        // private method for UTF-8 decoding
        _utf8_decode: function (utftext)
        {
            var string = "";
            var i = 0;
            var c = c1 = c2 = 0;

            while (i < utftext.length)
            {

                c = utftext.charCodeAt(i);

                if (c < 128)
                {
                    string += String.fromCharCode(c);
                    i++;
                }
                else if ((c > 191) && (c < 224))
                {
                    c2 = utftext.charCodeAt(i + 1);
                    string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                    i += 2;
                }
                else
                {
                    c2 = utftext.charCodeAt(i + 1);
                    c3 = utftext.charCodeAt(i + 2);
                    string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                    i += 3;
                }

            }
            return string;
        }
    }

最初，我正在做这样的事情......

getFileBuffer = function (file)
{
    var deferred = $.Deferred();
    var reader = new FileReader();
    reader.onload = function (e)
    {
        deferred.resolve(e.target.result);
    }
    reader.onerror = function (e)
    {
        deferred.reject(e.target.error);
    }
    reader.readAsArrayBuffer(file);

    return deferred.promise();
};

但当然这是HTML5和诸如此类的独家。所以，当我打电话给我的ajax函数时，我会从文件阅读器传入这个数组缓冲区，瞧！它会工作。现在我试图模仿IE8的相同功能。这可能吗？

由于

Answer 1

前段时间我写了一些函数我认为是二进制安全的，这里有相关的功能; base64To6和（可能名称不当）base6To8。

var chars = (
        'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
        'abcdefghijklmnopqrstuvwxyz' +
        '0123456789+/'
    ),
    inver = {}, i;
for (i = 0; i < chars.length; ++i) {
    inver[chars[i]] = i;
}

function base64To6(b64) {
    var arr6 = [],
        i = b64.length, lenMod = 0;
    while (b64.charAt(--i) === '=')
        ++lenMod;
    for (i = 0; i < b64.length - lenMod; ++i)
        arr6.push(inver[b64.charAt(i)]);
    i = b64.length & 3;
    if (i) i = 4 - i;
    i = i + b64.length;
    arr6.byteLength = 3 * i / 4 - lenMod;
    return arr6;
}

function base6To8(arr6) {
    var arr8 = [], i,
        e1, e2, e3,
        s1, s2, s3, s4,
        d1, d2, d3, d4;
    for (i = 0; i < arr6.length; i += 4) {
        s1 = (d1 = arr6[i]    ) & 63;
        s2 = (d2 = arr6[i + 1]) & 63;
        s3 = (d3 = arr6[i + 2]) & 63;
        s4 = (d4 = arr6[i + 3]) & 63;
        // xxxxxx xxyyyy yyyyzz zzzzzz
        e1 = ( s1       << 2) + (s2 >>> 4);
        e2 = ((s2 & 15) << 4) + (s3 >>> 2);
        e3 = ((s3 &  3) << 6) +  s4       ;
        arr8.push(e1);
        if (d3 !== undefined)
            arr8.push(e2, e3);
        else if (d2 !== undefined )
            arr8.push(e2);
    }
    if (arr6.byteLength !== undefined)
        arr8.length = +arr6.byteLength;
    return arr8;
}

现在，如果你这样做

var int8arr = base6to8(base64to6(data));

您将拥有整数的数组（最多8位数字）， Base64 代表。 JavaScript 不会将 Int8 用于 Number ，因此您无法立即使用此数组。

不幸的是，据我所知， IE8 不支持UInt8Array或Blob，这样可以让您愉快地使用二进制数据，所以我就是不确定你想从哪里拿到它。

Base64 - 文件已损坏

1 个答案: