使用HttpURLConnection发送post

我有一个node.js,它用两个参数(name和pass)等待post:

app.post('/login.html', function (req, res) {

    log.info(req.body);
    userName = req.body.name;
    pass = req.body.pass;
    ...
}

我试图通过简单的java应用程序发送带有2个参数的post,但我看不到它是否到达node.js。

我错过了什么?

public static void main(String[] args) {
    URL url;
    HttpURLConnection urlConnection = null;
    try {
        url = new URL("http://83.63.118.111:31011/login.html");

        urlConnection = (HttpURLConnection) url.openConnection();               
        urlConnection.setReadTimeout(10000);
        urlConnection.setRequestProperty("Content-Type", "application/json; charset=UTF-8");

        urlConnection.setConnectTimeout(10000);
        urlConnection.setRequestMethod("POST");
        urlConnection.setDoInput(true);
        urlConnection.setDoOutput(true);

        OutputStream os = urlConnection.getOutputStream();
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));          
        String str = "name='root'&pass='123456'";
        //System.out.print(str);
        writer.write(str);
        writer.flush();
        Thread.sleep(100);
        writer.close();
        os.close();       
}