使用自定义JavaScript在混合应用程序中使用Cordova插件下载为PDF

Question

我实际上需要在混合应用程序中以pdf格式下载文档。我在其中添加了自定义javascript下载功能。我添加的脚本实际上在这里遇到了问题。我已经附上了脚本供您参考，下面总是会出现错误提示文字。

    FileEntryfilesystem: FileSystemfullPath: "/Download/NaturalResource.pdf"isDirectory: falseisFile: truename: "NaturalResource.pdf"nativeURL: "file:///storage/emulated/0/Download/NaturalResource.pdf"__proto__: Entryconstructor: (name, fullPath, fileSystem, nativeURL)createWriter: (successCallback, errorCallback)file: (successCallback, errorCallback)__proto__: Object
    cordova_android.js:312 Error in Success callbackId: File581003392 : TypeError: downloadFile is not a function
    cordova_android.js:314 Uncaught TypeError: downloadFile is not a function
        at custom.js:97
        at win (DirectoryEntry.js:110)
        at Object.callbackFromNative (cordova_android.js:293)
        at processMessage (cordova_android.js:1081)
        at processMessages (cordova_android.js:1104)
        at pollOnce (cordova_android.js:973)
        at pollOnceFromOnlineEvent (cordova_android.js:960)
        at downloadStatementInMobileApp (custom.js:102)
        at Channel.onDeviceReady (custom.js:5)
        at Channel.fire (cordova_android.js:822)
    (anonymous) @ custom.js:97
    win @ DirectoryEntry.js:110
    callbackFromNative @ cordova_android.js:293
    processMessage @ cordova_android.js:1081
    processMessages @ cordova_android.js:1104
    pollOnce @ cordova_android.js:973
    pollOnceFromOnlineEvent @ cordova_android.js:960
    downloadStatementInMobileApp @ custom.js:102
    onDeviceReady @ custom.js:5
    Channel.fire @ cordova_android.js:822
    (anonymous) @ cordova_android.js:231

代码从这里开始

function downloadStatementInMobileApp() {
     var loginViaMobile = localStorage.getItem("MobileApp"); 

    if (loginViaMobile == 'true') {

        var userAgent = navigator.userAgent || navigator.vendor || window.opera;
        var documentDir;
        var fileDir;
    var fileURI = "https://www.kcesmjcollege.in/ICT/Geography/Natural%20Rsources.pdf";

        if (/android/i.test(userAgent)) {
            documentDir = cordova.file.externalRootDirectory;
            fileDir = 'Download';
        } else if (/iPhone/.test(userAgent) && !window.MSStream) {
            documentDir = cordova.file.documentsDirectory;
            fileDir = 'Documents';
        }

        window.resolveLocalFileSystemURL(documentDir, function(fs) {
            fs.getDirectory(fileDir, {
                create: true,
                exclusive: false
            }, function(directory) {
            directory.getFile("NaturalResource.pdf", {                                                              
                    create: true,
                    exclusive: false
                }, function(fileEntry) {
                    console.log(fileEntry);
                    downloadFile(fileEntry, fileURI)
                }, onFileTranferError);
            }, onFileTranferError);
        }, onFileTranferError);

        var downloadFile = function(fileEntry, uri) {
        var fileTransfer = new FileTransfer();
        var fileURL = fileEntry.toURL();
            fileTransfer.download(
                uri,
                fileURL,
                function(entry) {
                    logDebugMessage('file transfer complete: ' + entry.toURL());
                    // navigator.notification.alert('Your file has been stored in the '+fileDir+' folder', null, 'Download Success', 'Done');
                    openPDFViewer(entry);
                },
                onFileTranferError,
                null // or, pass false
            );
        };

        var openPDFViewer = function(fileEntry) {
        var url = fileEntry.toURL();
        var onError = function(error) {
                console.log(error);
            };
            var mimeType = 'application/pdf';
            cordova.plugins.fileOpener2.open(url, mimeType, {
                error: function(e) {
                    console.log(e);
                },
                success: function() {}
            });
        };

        var onFileTranferError = function(error) {
            navigator.notification.alert('Sorry something went wrong', null, 'Download Failed', 'Done');
            console.log('download error source ' + error.source);
            console.log('download error target ' + error.target);
            console.log('download error code' + error.code);
        };

        var logDebugMessage = function(message) {
        var debug_mode = false;
            if (debug_mode) {
                console.log(message);
            }
        };
    }
}

我没有得到successCallBack，这就是为什么我失败了。但我不确定。请分享您对此的见解。

插件文件传输会返回此sucessCallBack吗？