如何使用expressJS/connect/crypto获得（大）文件的校验和？

Question

  //express setup app.js
  app.use('/upload',express.bodyParser({
      defer : true, //enable progress event
      keepExtensions : true,
      limit : app.locals.fileLimit,
      uploadDir : path.join( __dirname, '..', 'tmp'),
      hash : true //this doesnt appear to do anything
  }));

  //express route routes.js
  app.post("/upload", function(req, res){

      var fs     = require('fs');
      var format = require('util').format;

      req.form.hash = true; //this doesnt return the hash for some reason

      req.form.on('fileBegin', function(err) {
         log.info("Starting new upload...");
      });

      req.form.on('file', function(name, file) {
          fs.rename(file.path, req.form.uploadDir + "/" + file.name);
        console.info(file);
      });

      req.form.on('error', function(err) {
         log.error('error',err);
         req.resume();
      });



      req.form.on('field', function(field, value) {
         log.info("Passed Field (%s=%s)...",field,value);
      });

      //this part event never gets called for some reason but
      //I imagine this is where you might do a hash update
      req.form.on('part', function(part){
        console.log('PART upload %s %s', part.name, part.filename);
        var out = fs.createWriteStream('../tmpstrm/' + part.filename);
        part.pipe(out);
      });


      req.form.on('progress', function(bytesReceived, bytesExpected) {
          var percent = (bytesReceived / bytesExpected * 100) | 0;
          console.info( "PROGRESS :"+ ((bytesReceived / bytesExpected)*100) + "% uploaded");
      });

      req.form.on('end', function() {
          var fileInfo = format('\nuploaded %s (%d Kb) to %s as %s'
            , req.files.upload.name
            , req.files.upload.size / 1024 | 0
            , req.files.upload.path
            , req.body.title);

          res.locals.fileInfo = fileInfo; //renders info in jade

          res.render('media/index');
      });

  });

var hash = crypto.createHash('sha1');
var data = // incoming file data

data.on('data', function(chunk){
  hash.update(chunk);
});
data.on('end', function(){
  var sha = hash.digest('hex');

  // Do something with it
})

Answer 1

在我的Writer-Digest npm模块源代码中，您可能会发现一些示例代码很有帮助：

https://github.com/focusaurus/writers-digest/blob/ab52ffca6e989ca657dc449e05ff258c428fa3af/index.js#l38

但基本上有两种方法：