解决kkFileView4.4.0版本pdf、word不能预览问题

这里使用的是http下载流url预览，遇到的问题。

官方使用指南：kkFileView - 在线文件预览

1 前端测试代码

1.1 官方示例代码

1.2 本人测试代码

注意：要给预览文件的url进行编码encodeURIComponent(Base64.encode(previewUrl))。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>

</head>
<body>
<h2>在线预览</h2>
<button type="button" onclick="kkFileView()">点击在线预览</button>
</body>
</html>
<script>
    var Base64 = {

        // private property
        _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

        //从普通字符串转换成Base64字符串的函数
        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;
        },

        //从Base64字符串转换成普通字符串的函数
        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;
        },

        //将普通字符串转换成UTF8编码的函数
        _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;
        },

        //将UTF8编码的字符串转换成普通字符串的函数
        _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;
        }
    }

  function kkFileView(){
    // pdf的文件流
    var originUrl  = 'http://192.168.1.58:8080/getFile?s/lV3bcibQiz34TStDR0NJ3tYfr1fqIvKRrtvEOy5ATi3a7u18wax87gN4DWjch/hcpeqQS8mQMoAYMDIXRzEpqtYk0H7DV/+pmYS/KtdPpk0tQrLSnT5OK8ND6QQgaTypPSswbJNvwhs+l5fE4GHLnvBX+kD9J42YAKO6VzAdzFmyonGjiAbegeLD4QspUcXXsdNSzz/7fDeRjDzc0M+HlMMS8/CiuMUmHqL4ErjuNF4Mn3s42UveYOHlukb0p4PCIJlhZeRBx4zXlTOcLlXItZKVb6gBVHVBH9e6ZpfTuIQJ4VRSN3twEOuIsBZ83w3SIepUH9oaA=';
    // 使用fullfilename=xxx给文件指定名称
    var previewUrl = originUrl + '&fullfilename=1.pdf';
    window.open('http://127.0.0.1:8012/onlinePreview?url='+encodeURIComponent(Base64.encode(previewUrl)))
  }
</script>

2 测试

点击在线预览按钮出现以下情况：

3 解决下载失败报错

3.1 报错信息

下载失败:org.springframework.web.client.HttpServerErrorException$InternalServerError: 500 Internal Server Error: [<!DOCTYPE html><html><head><title>Apache Tomcat/8.0.30 - Error report</title><style type="text/css">H1 {font-family:Tahoma,Arial,sans-serif;color:white;background-color:#525D76;font-size:22px;} H2 {fo... (1984 bytes)]