java发起http请求获取返回的Json对象方法

/**
 * Created by david on 2017-7-5.
 */
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
public class HttpRequestUtil {
 /**
  * 发起http请求并获取结果
  * @param requestUrl 请求地址
  */
 public static JsonObject getXpath(String requestUrl){
  String res="";
  JsonObject object = null;
  StringBuffer buffer = new StringBuffer();
  try{
   URL url = new URL(requestUrl);
   HttpURLConnection urlCon= (HttpURLConnection)url.openConnection();
   if(200==urlCon.getResponseCode()){
    InputStream is = urlCon.getInputStream();
    InputStreamReader isr = new InputStreamReader(is,"utf-8");
    BufferedReader br = new BufferedReader(isr);
    String str = null;
    while((str = br.readLine())!=null){
     buffer.append(str);
    }
    br.close();
    isr.close();
    is.close();
    res = buffer.toString();
    JsonParser parse =new JsonParser();
    object = (JsonObject) parse.parse(res);
   }
  }catch(IOException e){
   e.printStackTrace();
  }
  return object;
 }
 public static JsonObject postDownloadJson(String path,String post){
  URL url = null;
  try {
   url = new URL(path);
   HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
   httpURLConnection.setRequestMethod("POST");// 提交模式
   // conn.setConnectTimeout(10000);//连接超时 单位毫秒
   // conn.setReadTimeout(2000);//读取超时 单位毫秒
   // 发送POST请求必须设置如下两行
   httpURLConnection.setDoOutput(true);
   httpURLConnection.setDoInput(true);
   // 获取URLConnection对象对应的输出流
   PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
   // 发送请求参数
   printWriter.write(post);//post的参数 xx=xx&yy=yy
   // flush输出流的缓冲
   printWriter.flush();
   //开始获取数据
   BufferedInputStream bis = new   BufferedInputStream(httpURLConnection.getInputStream());
   ByteArrayOutputStream bos = new ByteArrayOutputStream();
   int len;
   byte[] arr = new byte[1024];
   while((len=bis.read(arr))!= -1){
    bos.write(arr,0,len);
    bos.flush();
   }
   bos.close();
   JsonParser parse = new JsonParser();
   return (JsonObject)parse.parse(bos.toString("utf-8"));
  } catch (Exception e) {
   e.printStackTrace();
  }
  return null;
 }
 //测试
 public static void main(String args [] ) {
  JsonObject res = null;
 //  res = getXpath("http://ip.taobao.com/service/getIpInfo.php?ip=63.223.108.42");
  res = postDownloadJson("http://ip.taobao.com/service/getIpInfo.php?ip=63.223.108.42","123");
  System.out.println(res);
  System.out.println(res.get("code"));
  System.out.println(res.get("data"));
 }
}