我的Express应用程序正在从浏览器接收base64编码的PNG(从画布生成的toDataURL())，并将其写入一个文件。但该文件不是有效的图像文件，“file”实用程序只是将其标识为“数据”。
var body = req.rawBody,
base64Data = body.replace(/^data:image\/png;base64,/,""),
binaryData = new Buffer(base64Data, 'base64').toString('binary');
require("fs").writeFile("out.png", binaryData, "binary", function(err) {
console.log(err); // writes out file without error, but it's not a valid image
});
当前回答
这是我的完整解决方案，它将读取任何base64图像格式，并将其保存在数据库中的适当格式:
// Save base64 image to disk
try
{
// Decoding base-64 image
// Source: http://stackoverflow.com/questions/20267939/nodejs-write-base64-image-file
function decodeBase64Image(dataString)
{
var matches = dataString.match(/^data:([A-Za-z-+\/]+);base64,(.+)$/);
var response = {};
if (matches.length !== 3)
{
return new Error('Invalid input string');
}
response.type = matches[1];
response.data = new Buffer(matches[2], 'base64');
return response;
}
// Regular expression for image type:
// This regular image extracts the "jpeg" from "image/jpeg"
var imageTypeRegularExpression = /\/(.*?)$/;
// Generate random string
var crypto = require('crypto');
var seed = crypto.randomBytes(20);
var uniqueSHA1String = crypto
.createHash('sha1')
.update(seed)
.digest('hex');
var base64Data = 'data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAZABkAAD/4Q3zaHR0cDovL25zLmFkb2JlLmN...';
var imageBuffer = decodeBase64Image(base64Data);
var userUploadedFeedMessagesLocation = '../img/upload/feed/';
var uniqueRandomImageName = 'image-' + uniqueSHA1String;
// This variable is actually an array which has 5 values,
// The [1] value is the real image extension
var imageTypeDetected = imageBuffer
.type
.match(imageTypeRegularExpression);
var userUploadedImagePath = userUploadedFeedMessagesLocation +
uniqueRandomImageName +
'.' +
imageTypeDetected[1];
// Save decoded binary image to disk
try
{
require('fs').writeFile(userUploadedImagePath, imageBuffer.data,
function()
{
console.log('DEBUG - feed:message: Saved to disk image attached by user:', userUploadedImagePath);
});
}
catch(error)
{
console.log('ERROR:', error);
}
}
catch(error)
{
console.log('ERROR:', error);
}
其他回答
从base64字符串文件转换为png图像。
有4个变体。
var {promisify} = require('util');
var fs = require("fs");
var readFile = promisify(fs.readFile)
var writeFile = promisify(fs.writeFile)
async function run () {
// variant 1
var d = await readFile('./1.txt', 'utf8')
await writeFile("./1.png", d, 'base64')
// variant 2
var d = await readFile('./2.txt', 'utf8')
var dd = new Buffer(d, 'base64')
await writeFile("./2.png", dd)
// variant 3
var d = await readFile('./3.txt')
await writeFile("./3.png", d.toString('utf8'), 'base64')
// variant 4
var d = await readFile('./4.txt')
var dd = new Buffer(d.toString('utf8'), 'base64')
await writeFile("./4.png", dd)
}
run();
简单的方法将base64图像转换为文件，并保存为一些随机id或名称。
// to create some random id or name for your image name
const imgname = new Date().getTime().toString();
// to declare some path to store your converted image
const path = yourpath.png
// image takes from body which you uploaded
const imgdata = req.body.image;
// to convert base64 format into random filename
const base64Data = imgdata.replace(/^data:([A-Za-z-+/]+);base64,/, '');
fs.writeFile(path, base64Data, 'base64', (err) => {
console.log(err);
});
// assigning converted image into your database
req.body.coverImage = imgname
下面的函数保存文件，只要传递你的base64文件，它返回文件名保存在DB中。
import fs from 'fs';
const uuid = require('uuid/v1');
/*Download the base64 image in the server and returns the filename and path of image.*/
function saveImage(baseImage) {
/*path of the folder where your project is saved. (In my case i got it from config file, root path of project).*/
const uploadPath = "/home/documents/project";
//path of folder where you want to save the image.
const localPath = `${uploadPath}/uploads/images/`;
//Find extension of file
const ext = baseImage.substring(baseImage.indexOf("/")+1, baseImage.indexOf(";base64"));
const fileType = baseImage.substring("data:".length,baseImage.indexOf("/"));
//Forming regex to extract base64 data of file.
const regex = new RegExp(`^data:${fileType}\/${ext};base64,`, 'gi');
//Extract base64 data.
const base64Data = baseImage.replace(regex, "");
const filename = `${uuid()}.${ext}`;
//Check that if directory is present or not.
if(!fs.existsSync(`${uploadPath}/uploads/`)) {
fs.mkdirSync(`${uploadPath}/uploads/`);
}
if (!fs.existsSync(localPath)) {
fs.mkdirSync(localPath);
}
fs.writeFileSync(localPath+filename, base64Data, 'base64');
return filename;
}
我还必须保存Base64编码的图像，这些图像是数据url的一部分，所以我最终制作了一个小的npm模块来做这件事，以防我(或其他人)将来需要再次这样做。叫做ba64。
简单地说，它接受一个带有Base64编码图像的数据URL，并将图像保存到您的文件系统中。它可以同步或异步保存。它还有两个辅助函数，一个用于获取图像的文件扩展名，另一个用于从数据中分离Base64编码:方案前缀。
这里有一个例子:
var ba64 = require("ba64"),
data_url = "data:image/jpeg;base64,[Base64 encoded image goes here]";
// Save the image synchronously.
ba64.writeImageSync("myimage", data_url); // Saves myimage.jpeg.
// Or save the image asynchronously.
ba64.writeImage("myimage", data_url, function(err){
if (err) throw err;
console.log("Image saved successfully");
// do stuff
});
安装:npm i ba64 -S。Repo在GitHub上:https://github.com/HarryStevens/ba64。
P.S.后来我想到ba64可能是一个不好的模块名称，因为人们可能认为它进行Base64编码和解码，但事实并非如此(有很多模块已经这样做了)。哦。
这是我的完整解决方案，它将读取任何base64图像格式，并将其保存在数据库中的适当格式:
// Save base64 image to disk
try
{
// Decoding base-64 image
// Source: http://stackoverflow.com/questions/20267939/nodejs-write-base64-image-file
function decodeBase64Image(dataString)
{
var matches = dataString.match(/^data:([A-Za-z-+\/]+);base64,(.+)$/);
var response = {};
if (matches.length !== 3)
{
return new Error('Invalid input string');
}
response.type = matches[1];
response.data = new Buffer(matches[2], 'base64');
return response;
}
// Regular expression for image type:
// This regular image extracts the "jpeg" from "image/jpeg"
var imageTypeRegularExpression = /\/(.*?)$/;
// Generate random string
var crypto = require('crypto');
var seed = crypto.randomBytes(20);
var uniqueSHA1String = crypto
.createHash('sha1')
.update(seed)
.digest('hex');
var base64Data = 'data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEAZABkAAD/4Q3zaHR0cDovL25zLmFkb2JlLmN...';
var imageBuffer = decodeBase64Image(base64Data);
var userUploadedFeedMessagesLocation = '../img/upload/feed/';
var uniqueRandomImageName = 'image-' + uniqueSHA1String;
// This variable is actually an array which has 5 values,
// The [1] value is the real image extension
var imageTypeDetected = imageBuffer
.type
.match(imageTypeRegularExpression);
var userUploadedImagePath = userUploadedFeedMessagesLocation +
uniqueRandomImageName +
'.' +
imageTypeDetected[1];
// Save decoded binary image to disk
try
{
require('fs').writeFile(userUploadedImagePath, imageBuffer.data,
function()
{
console.log('DEBUG - feed:message: Saved to disk image attached by user:', userUploadedImagePath);
});
}
catch(error)
{
console.log('ERROR:', error);
}
}
catch(error)
{
console.log('ERROR:', error);
}
