ajax跨域获取json数据应该如何操作

public static String analysisUrl(String url){
    HttpURLConnection httpConnection = null;
    String output = "";
    try {
      URL targetUrl = new URL(url);
      httpConnection = (HttpURLConnection) targetUrl.openConnection();
      httpConnection.setDoOutput(true);
      httpConnection.setRequestMethod("GET");
      httpConnection.setRequestProperty("Content-Type",
          "application/json");
      InputStreamReader isr = new InputStreamReader(httpConnection
          .getInputStream(),"utf-8");
      BufferedReader responseBuffer = new BufferedReader(isr);
      output = responseBuffer.readLine();
 
    } catch (Exception e) {
 
    } finally {
      httpConnection.disconnect();
    }
    return output;
  }