从NodeJS返回二进制数据

Question

I have a function called ReadBinaryData() which I would like to create a Read Stream to read binary data and return the binary data back to the calling function via a callback. It seems you can do this w/ Node a few different ways and I have read conflicting info on how to do it. I think I should be using the Buffer object, but not really sure how. I have the following, but it does not seem to be working correctly. Any suggestions ?

function ReadBinaryData(successCallback){               
    var streamHandle = fs.createReadStream("PATH TO FILE",  {encoding: 'binary'});      
    var contentRead = '';       
   streamHandle.addListener('data', function(data) {            
        contentRead += data;                            
    });

   streamHandle.addListener('end', function(data) {                         
        successCallback(contentRead);       
    });     
};

Answer 1

I used the nodejs Buffer in the 5.x branch. I'd check out the docs there and read up. There are a lot of new methods in there that will help with your binary stream. Although, the binary option is being removed in future versions, so you might want to rethink what you're doing and why.

http://nodejs.org/docs/v0.5.6/api/buffers.html

Here is an example use of the buffer though, i'm using the 5.x branch for this code, there is a similar method that is like writeUInt32LE but for binary. There are also corresponding read methods. If you can't use the 5.x branch, you might be able to look at the nodejs javascript libs and see how their method is transforming the string to the format you want.

  var cur = this.network.ipInt;
  var bcast = this.broadcast.ipInt;
  var addresses = new Buffer((bcast-cur)*10);
  var offset = 0;
  while (cur < bcast){
    cur += 1;
    addresses.writeUInt32LE(cur,offset);
    offset+=10;
  }