javascript 使用 Node.js 将 Base64 图像转换为原始二进制文件
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Convert Base64 image to raw binary with Node.js
提问by remotevision
I have found posts that are close to what I'm looking for, but I have not been able to successfully implement what I want. Here is the general flow:
我找到了与我正在寻找的内容相近的帖子，但我无法成功实现我想要的。这是一般流程：
- Submit photo with rest of venue data, as base64 data
- Strip data prefix if it exists, so I have just the image base64 data
- 提交带有其余场地数据的照片，作为 base64 数据
- 如果存在，则去除数据前缀，所以我只有图像 base64 数据
var base64data = venue.image.replace(/^data:image\/png;base64,|^data:image\/jpeg;base64,|^data:image\/jpg;base64,|^data:image\/bmp;base64,/, '');
- Store Base64 data in GridFS via MongoDB (I'm using gridfstore)
- Then, I'd like to retrieve the image upon request as a raw image file via a URL.
- 通过 MongoDB 在 GridFS 中存储 Base64 数据（我正在使用gridfstore）
- 然后，我想根据请求通过 URL 作为原始图像文件检索图像。
// generic images route
server.get(version+'/images/:id', function(req, res) {
gridfstore.read( req.params.id, function(error,data) {
res.writeHead(200, {
'Content-Type': 'image/jpeg',
'Content-Length': data.buffer.length
});
res.end(data.buffer);
});
});
Basically, this method returns the Base64 bytes stored in GridFS. I have tried other methods but they don't return the raw image.
基本上，此方法返回存储在 GridFS 中的 Base64 字节。我尝试过其他方法，但它们不返回原始图像。
I'd like to pull up the image using URLs like this:
我想使用这样的 URL 拉出图像：
http://[localhost]/1/images/11dbcef0-257b-11e3-97d7-cbbea10abbcb
Here is a screenshot of the browser trace:
这是浏览器跟踪的屏幕截图：
回答by hexacyanide
You can take the string from MongoDB, create a new buffer instance, and specify an encoding when doing so. The resultant buffer will be in binary data.
您可以从 MongoDB 获取字符串，创建一个新的缓冲区实例，并在执行此操作时指定编码。结果缓冲区将是二进制数据。
var b64str = /* whatever you fetched from the database */;
var buf = new Buffer(b64str, 'base64');
So in your implementation:
所以在你的实现中：
server.get(version+'/images/:id', function(req, res) {
gridfstore.read(req.params.id, function(err, data) {
var img = new Buffer(data.buffer, 'base64');
res.writeHead(200, {
'Content-Type': 'image/jpeg',
'Content-Length': img.length
});
res.end(img);
});
});
回答by John Williams
Make sure your string is correct. This worked for me..
确保你的字符串是正确的。这对我有用..
var buf = new Buffer(b64stringhere, 'base64');
var express = require('express'), app = express();
app.get('/img', function(r, s){
s.end(buf);
})
app.listen(80);
