Javascript 请求承诺:下载/检查文件';什么是MIME类型?
使用标准请求模块,我们可以运行以下脚本来检查文件的MIME类型Javascript 请求承诺:下载/检查文件';什么是MIME类型?,javascript,node.js,promise,Javascript,Node.js,Promise,使用标准请求模块,我们可以运行以下脚本来检查文件的MIME类型 var request = require('request'); var url = "http://www.somedomain.com/somepicture.jpg"; var magic = { jpg: 'ffd8ffe0', png: '89504e47', gif: '47494638' }; var options = { method: 'GET', url: url,
var request = require('request');
var url = "http://www.somedomain.com/somepicture.jpg";
var magic = {
jpg: 'ffd8ffe0',
png: '89504e47',
gif: '47494638'
};
var options = {
method: 'GET',
url: url,
encoding: null // keeps the body as buffer
};
request(options, function (err, response, body) {
if(!err && response.statusCode == 200){
var magicNumberInBody = body.toString('hex',0,4);
if (magicNumberInBody == magic.jpg ||
magicNumberInBody == magic.png ||
magicNumberInBody == magic.gif) {
console.log("It's an image!");
return true;
}
}
});
这是不言自明的。但是,当使用node.js并依赖承诺时,我们如何执行上述操作?我已尝试安装和使用,并编写了以下脚本
return rp("http://www.somedomain.com/somepicture.jpg")
.then((response) => {
var magicNumberInBody = response.toString('hex',0,4);
console.log(magicNumberInBody);
if (magicNumberInBody == magic.jpg ||
magicNumberInBody == magic.png ||
magicNumberInBody == magic.gif) {
console.log("It's an image!");
return true;
}
然而,对于任何不基于html/txt的内容,请求承诺似乎只是返回原始二进制文件
有谁知道如何将上述数据更改为有意义的内容,我可以轻松使用这些内容来确定MIME类型是否为jpg/png/gif?您必须使用
resolveWithFullResponse
选项:
rp({
uri:“http://www.somedomain.com/somepicture.jpg",
resolveWithFullResponse:true
})。然后(res=>{
console.log(res.headers['content-type'])
})
您必须使用resolveWithFullResponse
选项:
rp({
uri:“http://www.somedomain.com/somepicture.jpg",
resolveWithFullResponse:true
})。然后(res=>{
console.log(res.headers['content-type'])
})
我先做一个头部请求
// Download
return Image._head($, $(image).attr('src'))
.then((filename) => {
return Image._download($, filename)
})
.then((code) => {
return $
})
// Request
Request.head(options)
.then((data) => {
console.log(data)
// Get the content type
// const type = data['content-type']
// let ext = ''
// // Extract extension
// if (type === 'image/jpeg' || type === 'image/pjpeg') {
// ext = 'jpg'
// } else if (type === 'image/png') {
// ext = 'png'
// } else if (type === 'image/gif') {
// ext = 'gif'
// }
// Get filename
let filename = null
const disposition = data['content-disposition']
if (disposition && disposition.indexOf('inline') !== -1) {
var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/
var matches = filenameRegex.exec(disposition)
if (matches != null && matches[1]) {
filename = matches[1].replace(/['"]/g, '')
}
}
// Path
// const path = Path.join('./resources/images', `${filename}`)
// console.log('content-type:', data.headers['content-type'])
// console.log('content-length:', data.headers['content-length'])
// console.log('content-disposition:', data.headers['content-disposition'])
console.log('filename:', filename)
// resolve(data.html)
resolve(filename)
})
.catch((error) => {
resolve(new Error(`${error} - Instagram - ${src}`))
})
然后是另一个实际下载文件的请求
希望这在某种程度上有所帮助我先做一个head请求
// Download
return Image._head($, $(image).attr('src'))
.then((filename) => {
return Image._download($, filename)
})
.then((code) => {
return $
})
// Request
Request.head(options)
.then((data) => {
console.log(data)
// Get the content type
// const type = data['content-type']
// let ext = ''
// // Extract extension
// if (type === 'image/jpeg' || type === 'image/pjpeg') {
// ext = 'jpg'
// } else if (type === 'image/png') {
// ext = 'png'
// } else if (type === 'image/gif') {
// ext = 'gif'
// }
// Get filename
let filename = null
const disposition = data['content-disposition']
if (disposition && disposition.indexOf('inline') !== -1) {
var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/
var matches = filenameRegex.exec(disposition)
if (matches != null && matches[1]) {
filename = matches[1].replace(/['"]/g, '')
}
}
// Path
// const path = Path.join('./resources/images', `${filename}`)
// console.log('content-type:', data.headers['content-type'])
// console.log('content-length:', data.headers['content-length'])
// console.log('content-disposition:', data.headers['content-disposition'])
console.log('filename:', filename)
// resolve(data.html)
resolve(filename)
})
.catch((error) => {
resolve(new Error(`${error} - Instagram - ${src}`))
})
然后是另一个实际下载文件的请求
希望这在某种程度上有所帮助谢谢,我从中获得了更多有用的数据,但仍然无法运行实际的上述脚本。res.headers['content-type']只返回图像的“content-type”:“application/octet stream”。我需要查看实际的MIME类型。对不起,巴德,这是另一个问题,您对此无能为力,请参阅:谢谢,我从中获得了更多可用数据,但仍然无法运行实际的上述脚本。res.headers['content-type']只返回图像的“content-type”:“application/octet stream”。我需要查看实际的MIME类型。对不起,巴德,这是另一个问题,您对此无能为力,请参阅: