我有以下代码:
var http = require('http')
  ,https = require('https')
  ,fs = require('fs'),json;
var GOOGLE_API_KEY = process.env.GOOGLE_API_KEY;
var FUSION_TABLE_ID = "1epTUiUlv5NQK5x4sgdy1K47ACDTpHH60hbng1qw";
var options = {
  hostname: 'www.googleapis.com',
  port: 443,
  path: "/fusiontables/v1/query?sql=SELECT%20*%20"+FUSION_TABLE_ID+"FROM%20&key="+GOOGLE_API_KEY,
  method: 'GET'
};
http.createServer(function (req, res) {
  var file = fs.createWriteStream("chapters.json");
  var req = https.request(options, function(res) {
    res.on('data', function(data) {
      file.write(data);
    }).on('end', function() {
      file.end();
    });
  });
  req.end();
  req.on('error', function(e) {
    console.error(e);
  });
  console.log(req);
  res.writeHead(200, {'Content-Type': 'application/json'});
  res.end('Hello JSON');
}).listen(process.env.VMC_APP_PORT || 8337, null);
我如何返回 json 对象而不是“Hello JSON”?