NodeJS写入base64图像文件

Question

我的NodeJS-Server接收到base64编码的图片.

data:image/jpeg;base64,/9j/4QCcRXhpZgAASUkqAAgAAAA ... CiiigD//Z

收到的数据应保存为jpg.因此我使用Buffer和FileSystemWriter:

var imageBuffer = new Buffer(data, 'base64'); //console = <Buffer 75 ab 5a 8a ...
fs.writeFile("test.jpg", imageBuffer, function(err) { //... });

fs.writeFile不会调用错误.保存了jpeg文件,但我无法打开它.Image-Viewer说:

File is damaged or too big.

原始文件大6kb,新文件7kb.

Answer 1

您必须从中删除网址元信息data:image/jpeg.(重申@CBroe所说的)这是一个从输入字符串返回正确信息的小函数.

var data = 'data:image/jpeg;base64,iVBORw0KGgoAAAANSUhEUgAAA..kJggg==';

function decodeBase64Image(dataString) {
  var matches = dataString.match(/^data:([A-Za-z-+\/]+);base64,(.+)$/),
    response = {};

  if (matches.length !== 3) {
    return new Error('Invalid input string');
  }

  response.type = matches[1];
  response.data = new Buffer(matches[2], 'base64');

  return response;
}

var imageBuffer = decodeBase64Image(data);
console.log(imageBuffer);
// { type: 'image/jpeg',
//   data: <Buffer 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 00 00 00 b4 00 00 00 2b 08 06 00 00 00 d1 fd a2 a4 00 00 00 04 67 41 4d 41 00 00 af c8 37 05 8a e9 00 00 ...> }

然后,您可以使用上述方法保存缓冲区.

fs.writeFile('test.jpg', imageBuffer.data, function(err) { ... });

Answer 2

另一种方法是在剥离元信息后使用fs.writeFile编码选项base64.

var image = 'data:image/jpeg;base64,iVBORw0KGgoAAAANSUhEUgAAA..kJggg==';

var data = image.replace(/^data:image\/\w+;base64,/, '');

fs.writeFile(fileName, data, {encoding: 'base64'}, function(err){
  //Finished
});