java的POST

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

class javatest {
    public static void main(String[] args){
        URL url = null;
        HttpURLConnection conn = null;
        try {
            url = new URL("http://127.0.0.1/post.php");
            conn = (HttpURLConnection) url.openConnection();
            conn.setDoOutput(true);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-type","application/x-www-form-urlencoded");
            String str = "a=3,14159265358979323846264338327950288419716939937510";
            conn.getOutputStream().write(str.getBytes());
            conn.getOutputStream().flush();
            conn.getOutputStream().close();
            // Get the return code
            int code = conn.getResponseCode();
            System.out.println("code: "+code);
            String msg = conn.getResponseMessage();
            System.out.println("message: "+msg);
            // Get the return content
            BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream(),"utf-8"));
            String lines;
            while ((lines = reader.readLine())!=null){
                System.out.println(lines);
            }
        } catch (Exception e){
            e.printStackTrace();
        } finally {
            if (conn!=null){
                conn.disconnect();
            }
        }
    }
}