抽象 chrome 打包的应用程序文件系统以与 node-webkit 一起使用

Question

我目前有一个 chrome 打包应用程序，我们也将它移植到 iPad，但我想使用 node-webkit (nw.js) 使其可安装，我需要抽象 chrome 打包应用程序 API 以与 chrome 一起使用。文件系统。我目前用来保存的代码如下。

 var downloadFile = function (readUrl, next) {
     var xhr = new XMLHttpRequest();
    xhr.open('GET', readUrl);
     xhr.responseType = 'arraybuffer';

     xhr.onload = function (e) {
         if (this.status == 200) {
             var response = this.response;
            var params = {
                 type : 'saveFile',
                suggestedName : fileNameNoExtension,
                         //my code will inject the extension but in this case i just put in txt
                         accepts : [{
                         extensions : ['.txt']
                     }
                 ]
             }
            chrome.fileSystem.chooseEntry(params, function (writableFileEntry) {
                 debugger;
                writableFileEntry.createWriter(function (writer) {
                     debugger;
                    writer.onwriteend = function (e) {
                         return next(null)
                     };
                    writer.onerror = function (e) {};
                     writer.write(new Blob([response], {
                             type : 'application/octet-stream'
                         }));
                 });
             });

         } else {
             //alert
         }
     };
    xhr.onprogress = function (evt) {
         if (evt.lengthComputable) {
             console.log('progress: ' + Math.round(evt.loaded * 100 / evt.total));
         }
     }
    xhr.addEventListener("error", function () {
         return next('error')
     }, false);
    xhr.addEventListener("abort", function () {
         return next('abort')
     }, false);
    xhr.send();
 }

Answer 1

我创建了一个名为 interop.js 的文件，我将此脚本加载到我的 index.html 中，如果它是一个 nw.js 项目，它将处理对 fileStorage 的所有 chrome 打包应用程序 API 调用。如果它是一个 chrome 打包的应用程序，那么 chrome 将处理它自己的 API。

 //if process is undefined then it is not an nw.js project and we can ignore the rest of the code;
 if (typeof process == 'undefined') {}
 //this is a nw.js project, spoof the chrome packaged app API
 else {
     var fs = require('fs')
         chrome = new function () {
        var fileSystem = {
             //callback return readableFileEntry, which has a
            chooseEntry : function (params, callback) {
                 if (params.type == 'openFile') {
                     //open file choose
                    chooseFile(params, function (files) {
                         //this is technically an html5 "filelist"  we need to turn it into an array if there is more
                        //than one, and just return the single file if there isn't
                         if (!files) {
                             return callback(null)
                         }
                        async.map(files, function (file, cb) {
                             //normally chrome provides a 'readablefileentry' that will only give you the file
                            //asynchronously using the file() function
                             file.file = function (next) {
                                 return next(this);
                             }
                            cb(null, file)
                         }, function (err, files) {
                             if (files.length > 1) {
                                 return callback(files);
                             } else {
                                 return callback(files[0]);
                             }
                         })
                     })
                 } else if (params.type == 'saveFile') {
                     chooseFile(params, function (files) {
                         var file = files[0];
                        debugger;
                         file.createWriter = function (next) {
                             var writer = {
                                 write : function (blob) {
                                     debugger;
                                    var reader = new FileReader()
                                         reader.readAsArrayBuffer(blob)
                                        reader.addEventListener('loadend', function (e) {
                                             var binary = new Uint8Array(reader.result)
                                                 debugger;
                                             fs.writeFile(file.path, new Buffer(binary), function (err) {
                                                 //if the on error and writeend has been defined then callback, otherwise throw the error and log success
                                                if (err && writer.onerror) {
                                                     writer.onerror(err)
                                                 } else if (err) {
                                                     throw err
                                                 } else if (writer.onwriteend) {
                                                     writer.onwriteend()
                                                 } else {
                                                     console.log('file was written but no callback was defined')
                                                 }
                                             })
                                         });
                                 }
                             }
                            return next(writer)
                         }
                        return callback(file)
                     })
                 }
                function chooseFile(params, next) {
                     var fileHtml = '<input type="file"'
                         debugger;
                     if (params.acceptsMultiple)
                         fileHtml += ' multiple';
                     if (params.accepts && params.accepts.length > 0 && params.accepts[0].extensions) {
                         fileHtml += ' accept="'
                        for (var i = 0; i < params.accepts[0].extensions.length; i++) {
                             if (i != 0)
                                 fileHtml += ','
                                fileHtml += '.' + params.accepts[0].extensions[i]
                         }
                        fileHtml += '"'
                     }
                    if (params.suggestedName) {
                         fileHtml += ' nwsaveas="' + params.suggestedName + '"'
                     }

                     fileHtml += '>'

                     var chooser = $(fileHtml);
                    chooser.change(function (evt) {
                         debugger;
                        return next(chooser[0].files)
                     });

                     chooser.click();
                 }
             }
         }

         return {
             fileSystem : fileSystem,
         }
     };
 }