请使用一段java代码实现httpurlconnection如何发送post请求

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpPostExample {

private final String USER_AGENT = "Mozilla/5.0";

public static void main(String[] args) throws Exception {

HttpPostExample http = new HttpPostExample();

System.out.println("Testing 1 - Send Http POST request");
http.sendPost();

}

// HTTP POST request
private void sendPost() throws Exception {

String url = "http://www.example.com";
URL obj = new URL(url);
HttpURLConnection con = (HttpURLConnection) obj.openConnection();

//add reuqest header
con.setRequestMethod("POST");
con.setRequestProperty("User-Agent", USER_AGENT);
con.setRequestProperty("Accept-Language", "en-US,en;q=0.5");

String urlParameters = "param1=value1&param2=value2";

// Send post request
con.setDoOutput(true);
DataOutputStream wr = new DataOutputStream(con.getOutputStream());
wr.writeBytes(urlParameters);
wr.flush();
wr.close();

int responseCode = con.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + urlParameters);
System.out.println("Response Code : " + responseCode);

BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();

while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();

//print result
System.out.println(response.toString());

}

}