JSON没有得到电子邮件

Question

我用Facebook的，通过连接的servlet API从他的Facebook帐户检索用户的基本数据，我从Java appliation连接：

private void getUserMailAddressFromJsonResponse(String accessToken, 
     HttpSession httpSession) { 
    String email = null; 
    HttpClient httpclient = new DefaultHttpClient(); 
    try { 
     if (accessToken != null && !"".equals(accessToken)) { 
      String newUrl = "https://graph.facebook.com/me?access_token=" 
        + accessToken; 
      httpclient = new DefaultHttpClient(); 
      HttpGet httpget = new HttpGet(newUrl); 
      System.out.println("Get info from face --> executing request: " 
        + httpget.getURI()); 
      ResponseHandler<String> responseHandler = new BasicResponseHandler(); 
      String responseBody = httpclient.execute(httpget, 
        responseHandler); 
      JSONObject json = (JSONObject) JSONSerializer 
        .toJSON(responseBody); 
      System.out.println("Attributes inside Json "+json.toString()); 
      String facebookId = json.getString("id"); 
      String firstName = json.getString("first_name"); 
      String lastName = json.getString("last_name"); 
      email= json.getString("email"); // not founding email 

      // put user data in session 
      httpSession.setAttribute("FACEBOOK_USER", firstName + ","+lastName+","+email+","+facebookId); 

     } else { 
      System.err.println("Token za facebook je null"); 
     } 
    } catch (ClientProtocolException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } finally { 
     httpclient.getConnectionManager().shutdown(); 
    } 
    // return email; 
} 

除外：

net.sf.json.JSONException: JSONObject["email"] not found 

这是一个托管bean形成的URL的方法：

public String getFacebookUrlAuth() { 
    System.out.println("Called"); 
    HttpSession session = (HttpSession) FacesContext.getCurrentInstance() 
      .getExternalContext().getSession(false); 
    String sessionId = session.getId(); 
    System.out.println("SessionId:" + sessionId); 
    String appId = "3607596261352927"; 
    String redirectUrl = "http://localhost:8080/Gambak/index.sec"; 
    String returnValue = "https://www.facebook.com/dialog/oauth?client_id=" 
      + appId + "&redirect_uri=" + redirectUrl 
      + "&scope=email,user_birthday&state=" + sessionId; 
    System.out.println("return value: " + returnValue); 
    return returnValue; 
} 

奇怪的是，我成功地收到了3天前的电子邮件，它运行良好，当我今天尝试它时，我得到了这个异常！

Answer 1

“请注意，即使您要求获得电子邮件许可，也无法保证您会收到电子邮件地址。例如，如果某人使用电话号码而不是电子邮件地址注册Facebook，则电子邮件字段可能是空。“

https://developers.facebook.com/docs/facebook-login/permissions/v2.5#reference-email