首页 \ 问答 \ js.writeFile没有正确编写Blob(js.writeFile not writing Blob correctly)

js.writeFile没有正确编写Blob(js.writeFile not writing Blob correctly)

 我有一个Angular服务，具有写文件的功能。 该功能可以在Ionic或Electron平台上运行。 对于Ionic，它使用$ cordovaFile进行文件操作，而对于Electron，它使用节点fs库。 
 

 功能如下： 
 

writeFile(filename: string, dirname: string, data: string | Blob, replace?: boolean): ngCordova.IFilePromise<ProgressEvent> {
    if (this.isElectron) {
        let promiseObj = this.$q.defer();
        if (replace) {
            try {
                fs.unlinkSync('./' + dirname + '/' + filename);
            }
            catch (err) {
                //err
            }
        }
        fs.writeFile('./' + dirname + '/' + filename, data, 'binary', () => {
            promiseObj.resolve(true);
        });

        return promiseObj.promise;
    }
    else {
        return this.$cordovaFile.writeFile(cordova.file.dataDirectory + dirname, filename, data, replace);
    }
};

 

 使用Ionic平台时，该功能正常，下载的文件被正确写出。 但是，当使用Electron平台时，所有下载的文件都包含字符串[object Blob] 。 
 

 使用fs将Blob写入文件的正确方法是什么？ 
 

 更多信息 
 

 数据最初在JSON消息中作为base64下载，但我们随后使用它 
 

let fileBlob = this.stringUtilityService.b64ToBlob(dataObj.Data[i].FileContents, 'image/png');

    this.fileSystemService.writeFile(dataObj.Data[i].FileName, 'icons', fileBlob);

 

 额外的信息 
 

 这是b64ToBlob（）函数，虽然据我所知，这个函数工作正常并正确返回一个blob，Ionic应用程序正确保存并可以显示。 
 

b64ToBlob(b64Data: string, contentType: string): any {
        let sliceSize = 512;

        let byteCharacters = atob(b64Data);
        let byteArrays = [];

        for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
            let slice = byteCharacters.slice(offset, offset + sliceSize);

            let byteNumbers = new Array(slice.length);
            for (let i = 0; i < slice.length; i++) {
                byteNumbers[i] = slice.charCodeAt(i);
            }

            let byteArray = new Uint8Array(byteNumbers);

            byteArrays.push(byteArray);
        }

        let blob = new Blob(byteArrays, { type: contentType });
        return blob;
    }


I have an Angular service with a function for writing files away. The function can work on either an Ionic or Electron platform. For Ionic, it uses $cordovaFile for file actions and for Electron it uses the node fs library.
 

The function is as follows:
 

writeFile(filename: string, dirname: string, data: string | Blob, replace?: boolean): ngCordova.IFilePromise<ProgressEvent> {
    if (this.isElectron) {
        let promiseObj = this.$q.defer();
        if (replace) {
            try {
                fs.unlinkSync('./' + dirname + '/' + filename);
            }
            catch (err) {
                //err
            }
        }
        fs.writeFile('./' + dirname + '/' + filename, data, 'binary', () => {
            promiseObj.resolve(true);
        });

        return promiseObj.promise;
    }
    else {
        return this.$cordovaFile.writeFile(cordova.file.dataDirectory + dirname, filename, data, replace);
    }
};

 

When the Ionic platform is used, the function works fine and the downloaded files are written away correctly. However, when the Electron platform is used, all the downloaded files contain is the string [object Blob].
 

What is the correct way to write Blobs to files using fs?
 

MORE INFO
 

The data originally comes down as base64 in a JSON message but we then do this with it 
 

let fileBlob = this.stringUtilityService.b64ToBlob(dataObj.Data[i].FileContents, 'image/png');

    this.fileSystemService.writeFile(dataObj.Data[i].FileName, 'icons', fileBlob);

 

EXTRA MORE INFO
 

Here is the b64ToBlob() function, although as far as i can tell this function works fine and correctly returns a blob which the Ionic app correctly saves away and can display.
 

b64ToBlob(b64Data: string, contentType: string): any {
        let sliceSize = 512;

        let byteCharacters = atob(b64Data);
        let byteArrays = [];

        for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
            let slice = byteCharacters.slice(offset, offset + sliceSize);

            let byteNumbers = new Array(slice.length);
            for (let i = 0; i < slice.length; i++) {
                byteNumbers[i] = slice.charCodeAt(i);
            }

            let byteArray = new Uint8Array(byteNumbers);

            byteArrays.push(byteArray);
        }

        let blob = new Blob(byteArrays, { type: contentType });
        return blob;
    }


原文：https://stackoverflow.com/questions/41808702
更新时间：2022-10-12 09:10

最满意答案

 这是使用pprint漂亮打印的data ： 
 

{'service_group_stat': {'cur_conns': 71,
                    'cur_reqs': 0,
                    'member_stat_list': [{'cur_conns': 11,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 447460215,
                                          'req_pkts': 3134918,
                                          'resp_bytes': 10134966691,
                                          'resp_pkts': 7834233,
                                          'server': 'WWW0006',
                                          'status': 1,
                                          'tot_conns': 52311,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 5,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 548725475,
                                          'req_pkts': 3870142,
                                          'resp_bytes': 12396718148,
                                          'resp_pkts': 9572363,
                                          'server': 'WWW0005',
                                          'status': 1,
                                          'tot_conns': 61464,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 15,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 711362272,
                                          'req_pkts': 5051483,
                                          'resp_bytes': 15868605964,
                                          'resp_pkts': 12282023,
                                          'server': 'WWW0004',
                                          'status': 1,
                                          'tot_conns': 80898,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 23,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 92624447982,
                                          'req_pkts': 575717964,
                                          'resp_bytes': 1832290858664,
                                          'resp_pkts': 1417192127,
                                          'server': 'WWW0003',
                                          'status': 1,
                                          'tot_conns': 7265009,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 14,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 97240370978,
                                          'req_pkts': 634692796,
                                          'resp_bytes': 1909851841929,
                                          'resp_pkts': 1479318756,
                                          'server': 'WWW0002',
                                          'status': 1,
                                          'tot_conns': 7130096,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 3,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 93596613191,
                                          'req_pkts': 586137971,
                                          'resp_bytes': 1839297678302,
                                          'resp_pkts': 1422848182,
                                          'server': 'WWW0001',
                                          'status': 1,
                                          'tot_conns': 7172117,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0}],
                    'name': 'SG_ACCOUNT.BUSINESS.COM_443',
                    'protocol': 2,
                    'req_bytes': 285168980113,
                    'req_pkts': 1808605274,
                    'resp_bytes': 5619840669698,
                    'resp_pkts': 4349047684,
                    'status': 3,
                    'tot_conns': 21761895,
                    'total_reqs': 0,
                    'total_reqs_succ': 0}}

 

 使用此信息，我们现在可以处理它。 对于member_stat_list每个服务器，我们可以按您所说的格式打印数据： 
 

for server in data["service_group_stat"][["member_stat_list"]:
    print("Server:".ljust(20," ")+server["server"].ljust(32," ")+"Server Connections:".ljust(24," ")+str(server["cur_conns"]))


Here is data pretty-printed using pprint:
 

{'service_group_stat': {'cur_conns': 71,
                    'cur_reqs': 0,
                    'member_stat_list': [{'cur_conns': 11,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 447460215,
                                          'req_pkts': 3134918,
                                          'resp_bytes': 10134966691,
                                          'resp_pkts': 7834233,
                                          'server': 'WWW0006',
                                          'status': 1,
                                          'tot_conns': 52311,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 5,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 548725475,
                                          'req_pkts': 3870142,
                                          'resp_bytes': 12396718148,
                                          'resp_pkts': 9572363,
                                          'server': 'WWW0005',
                                          'status': 1,
                                          'tot_conns': 61464,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 15,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 711362272,
                                          'req_pkts': 5051483,
                                          'resp_bytes': 15868605964,
                                          'resp_pkts': 12282023,
                                          'server': 'WWW0004',
                                          'status': 1,
                                          'tot_conns': 80898,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 23,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 92624447982,
                                          'req_pkts': 575717964,
                                          'resp_bytes': 1832290858664,
                                          'resp_pkts': 1417192127,
                                          'server': 'WWW0003',
                                          'status': 1,
                                          'tot_conns': 7265009,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 14,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 97240370978,
                                          'req_pkts': 634692796,
                                          'resp_bytes': 1909851841929,
                                          'resp_pkts': 1479318756,
                                          'server': 'WWW0002',
                                          'status': 1,
                                          'tot_conns': 7130096,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0},
                                         {'cur_conns': 3,
                                          'cur_reqs': 0,
                                          'port': 81,
                                          'req_bytes': 93596613191,
                                          'req_pkts': 586137971,
                                          'resp_bytes': 1839297678302,
                                          'resp_pkts': 1422848182,
                                          'server': 'WWW0001',
                                          'status': 1,
                                          'tot_conns': 7172117,
                                          'total_reqs': 0,
                                          'total_reqs_succ': 0}],
                    'name': 'SG_ACCOUNT.BUSINESS.COM_443',
                    'protocol': 2,
                    'req_bytes': 285168980113,
                    'req_pkts': 1808605274,
                    'resp_bytes': 5619840669698,
                    'resp_pkts': 4349047684,
                    'status': 3,
                    'tot_conns': 21761895,
                    'total_reqs': 0,
                    'total_reqs_succ': 0}}

 

Using this info, we can now process it. For each server in member_stat_list, we can print the data in the format you said like this:
 

for server in data["service_group_stat"][["member_stat_list"]:
    print("Server:".ljust(20," ")+server["server"].ljust(32," ")+"Server Connections:".ljust(24," ")+str(server["cur_conns"]))

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