How to write parameter-value into a servlet

Question

I use URL , URLEncoder and HttpURLConnection in java.net package to connect to a servlet in WebSphere 3.0.2 server with Https protocol. I try to write the necessary parameters into one servlet . But the http response code is always 500 ,means Server Error.
Why can I not get the full html code or Ok http response code as I get the page from IE with inputing parameter directly ? The inputed String in IE address bar is "https://xxxHost/xxxDir/servlet/xxxServlet?para1=value1&para2=value2 ".
I try to use all kinds of character encoding But the result code is alaways 500.
The following code is my test code .
//JVM 1.4.0_01
//***********************Code Start*************************
URL url=new URL("https://xxxHost/xxxDir/servlet/xxxServlet");
HttpURLConnection Conn=(HttpURLConnection)url.openConnection();
Conn.setDoOutput(true);
Conn.setDoInput(true);
Conn.connect();     
PrintWriter trxOut=new PrintWriter(Conn.getOutputStream());
String para1=URLEncoder.encode("para=value&para1=value1","ISO-8859-1");     
trxOut.print(para1);
trxOut.flush();
trxOut.close();     
Conn.getResponseCode();
//***********************Code End *************************
Where do i need or is error action? Thank you for this question .

Answer 1

So, when you hit your servlet from a browser with a url that has the query string of
para1=value1&para2=value2
do you bet a 500? If so, it's not your (client) codes fault.
To read the HTTP response see:
http://java.sun.com/docs/books/tutorial/networking/urls/readingWriting.html
Good luck
Lee