node.js – NodeJS base64图像编码/解码不太有效

// This tells node to load the filE into a Buffer 'original_data' because you
// have not specified an encoding for the returned values. If you provided an
// encoding,then original_data would be a String with that encoding.
fs.readFile(image_origial,original_data){

    // This tells node to take that buffer,and write it to the new filename.
    // Again no encoding is provided,so it will assume a Buffer or utf8 String.
    fs.writeFile('image_orig.jpg',function(err) {});

    // This tells node to create a new buffer from the old buffer,which means
    // it will iterate over original_data copying the bytes one at a time. But
    // they will be identical buffers. It will ignore the 'binary' argument
    // since the object you are passing isn't a String.
    // Then it encodes the content of that Buffer to base64,which is fine.
    var base64Image = new Buffer(original_data,'binary').toString('base64');

    // Here you decode the base64 to a buffer,which is fine,but then you
    // convert the buffer into a String with encoding 'binary'. This means that
    // it is a String object whose code points are bytes of the buffer.
    var decodedImage = new Buffer(base64Image,'base64').toString('binary');

    // Here you try to write that String object to a file. Since the argument you
    // have given is a String and you have not given an encoding argument for the
    // write command,then it will assume that 'utf8' is the encoding. It will try to
    // decode your binary String into a utf8 encoded buffer,and write that buffer.
    // This will cause it to fail because that encoding conversion is wrong.
    // Really through,'binary' is just wrong to use. Buffers are already binary.
    fs.writeFile('image_decoded.jpg',function(err) {});
});

下一个示例将起作用,但效率非常低,因为不需要一直更改编码,但我只想表明它是清楚的.如果你真的想要拥有特定的编码,你需要确保你是一致的.这些函数中的每一个都有一个编码参数.

fs.readFile(image_origial,'binary',function(err) {});
});

这是正确的方法.将所有内容保留为缓冲区,除非您将其设置为base64.

fs.readFile(image_origial,function(err) {});
    var base64Image = original_data.toString('base64');
    var decodedImage = new Buffer(base64Image,'base64');
    fs.writeFile('image_decoded.jpg',function(err) {});
});