相关代码：

var querystring = require('querystring'),
  fs = require('fs'),
  formidable = require('formidable');

function start(response) {
  console.log('Request handler "start" was called.');
  var body = '' +
    '' +
    '' +
    '' +
    '' +
    '
' +
    '' +
    '' +
    '
' +
    '' +
    '';

  response.writeHead(200, {
    'Content-Type': 'text/html'
  });
  response.write(body);
  response.end();

}

function upload(response, request) {
  console.log('Request handler "upload" was called.');
  var form = new formidable.IncomingForm();
  console.log('about to parse');
  form.parse(request, function (error, fields, files) {
    console.log('parsing done');
    fs.renameSync(files.upload.path, '/tmp/test.png');
    // 返回 upload 处理程序的处理结果。
    response.writeHead(200, {
      'Content-Type': 'text/html'
    });
    response.write('received image:
');
    response.write('')
    response.end();
  });

}

function show(response) {
  console.log('Request handler "show" was called.');
  fs.readFile('/tmp/test.png', 'binary', function (error, file) {
    if (error) {
      response.writeHead(500, {
        'Content-Type': 'text/plain'
      });
      response.write(error + '\n');
      response.end();
    } else {
      response.writeHead(200, {
        'Content-Type': 'image/png'
      });
      response.write(file, 'binary');
      response.end();
    }
  })
}
exports.start = start;
exports.upload = upload;
exports.show = show;

上传之后，可以在浏览器中看到。但是通过 root 帐号通过 SSH 在服务器上却看不到上传的文件。