Hello.java

import java.net.*;
import java.io.*;

public class Hello {
	public static void main(String[] args) {
    HttpURLConnection connection = null;
    String data = "{\"jsonrpc\": \"1.0\", \"method\": \"getaccountaddress\", \"params\": [\"a\"] }";
    String username = "rpc";
    String password = "rpc123";
    try {
      URL url = new URL("http://home.guten.me:9332");
      connection = (HttpURLConnection) url.openConnection();
      connection.setRequestMethod("POST");
      connection.setRequestProperty("Content-Type", "text/plain");
      connection.setRequestProperty("Content-Length", Integer.toString(data.getBytes().length));

      // 采用HTTP Basic Auth, 这里需要一个Base64 encoding, 我没有库, 运行起来就401 UnAuthorize 错误, 你应该会的
      /*
      String encoding = Base64Encoder.encode(username+":"+password);
      connection.setRequestProperty ("Authorization", "Basic " + encoding);
      */

      connection.setUseCaches(false);
      connection.setDoOutput(true);

      //Send request
      DataOutputStream wr = new DataOutputStream (connection.getOutputStream());
      wr.writeBytes(data);
      wr.close();

      //Get Response
      BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
      String inputLine;
      while ((inputLine = in.readLine()) != null)
          System.out.println(inputLine);
      in.close();
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (connection != null) {
        connection.disconnect();
      }
    }
	}
}