如何向服务器发送 请求

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

/** *//**
 * @author Huy Vanpon
 */
public class SendPoster
{
    private URL           url;
    
    private URLConnection conn;
    
    public void setURL(String urlAddr)
    {
        try
        {
            url = new URL(urlAddr);
            conn = url.openConnection();
        }
        catch (MalformedURLException ex)
        {
            ex.printStackTrace();
        }
        catch (IOException ex)
        {
            ex.printStackTrace();
        }
    }
    
    public void sendPost(String post)
    {
        conn.setDoInput(true);
        conn.setDoOutput(true);
        PrintWriter output;
        try
        {
            output = new PrintWriter(conn.getOutputStream());
            output.print(post);
            output.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
    
    public String getContent()
    {
        String line, result = "";
        try
        {
            conn.connect();
            BufferedReader in = new BufferedReader(new InputStreamReader(conn
                    .getInputStream()));
            while ((line = in.readLine()) != null)
            {
                result += line + "\n";
            }
            in.close();
        }
        catch (IOException ex)
        {
            ex.printStackTrace();
        }
        return result;
    }
    
    public static void main(String[] args)
    {
        String urlAddr = "http://www.ip138.com/ips8.asp";
        String post = "action=ip&ip=202.115.191.255";
        SendPoster test = new SendPoster();
        test.setURL(urlAddr);
        test.sendPost(post);
        String aa = test.getContent().trim();
        System.out.println(aa);
    }
}