Java 单例和用户对象持久性问题

我正在尝试为用户模型实现一个单例设计模式。我遇到的问题是维护一个对象，该对象存储在我的应用程序中任何时候要检索的所有数据。全局对象

我不确定应该在何处或如何实现全局用户对象。我从服务器检索JSON响应，然后在AsyncTask中从它创建一个用户对象，然后通过接口将该用户对象一直传递到NavigationActivity getCreatedUser方法

在该方法中我应该做什么？如果有的话？也许有什么办法可以查一下

这是我的用户模型，至少是其中的一部分

下面是异步任务

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当我创建一个单例类时，我在对象上创建了一个同步锁。也许这会有帮助？我会调查的。我不是真的在寻找这个答案的代码，除非它是一些愚蠢的简单的东西。实际上，我认为我缺少一个组件，所以我将研究同步锁。如果我没有弄错你想要什么，那么创建一个扩展类，将用户对象放在那里，并在任何地方访问它。

public class User {

static User _user;

int location_id, group_id, user_address_zip, user_refer, user_stat,
        user_bnav, user_jguide, user_mbooks, user_minvent, user_mfeed,
        user_mupdates, user_talert, user_tmessage, user_id;

float user_owes, user_owed;

String user_nick, user_password, user_salt, user_bday, user_title,
        user_name, user_address, user_address_lat, user_address_lng,
        user_address_street, user_address_street2, user_address_city,
        user_address_state, user_phone, user_phone_c, user_phone_w,
        user_phone_cell, user_phone_carrier, user_email, user_email_work,
        user_avatar, user_signature, user_created, user_auth, user_clock,
        user_onsite, user_return, user_return_to, user_company;

public User() {

}

public static User currentUser() {
    if (_user == null) {
        _user = new User();
    }
    return _user;

}

public int getUser_id() {
    return user_id;
}

public static class CreateUser extends AsyncTask<User, Void, User> {

    Context mContext;

    public interface CreateUserInterface {

        public void getCreatedUser(User user);

        public void getUserCreateErrorMessage(String error);

    }

    CreateUserInterface callback;

    public CreateUser(Context context) {
        // TODO Auto-generated constructor stub
        this.mContext = context;
        callback = (CreateUserInterface) context;
    }

    @Override
    protected User doInBackground(User... params) {
        ObjectMapper mapper = new ObjectMapper(); // create once, reuse
        User user = params[0];
        String url = ROUTE_USER_CREATE;
        HttpPost httppost = new HttpPost(url);
        HttpClient httpclient = new DefaultHttpClient();
        String UserJSONResponse = null;

        try {
            String jsonString = mapper.writeValueAsString(user);
            StringEntity m_stringEntity = new StringEntity(jsonString);

            httppost.setEntity(m_stringEntity);
            httppost.addHeader("Content-type", "application/json");

            HttpResponse postResponse = httpclient.execute(httppost);

            UserJSONResponse = EntityUtils.toString(postResponse
                    .getEntity());
            user = mapper.readValue(UserJSONResponse, User.class);

        } catch (JsonProcessingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return user;
    }

    @Override
    protected void onPostExecute(User result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
        //User user = new User();
        Log.e("USERNAME", result.getUser_name());
        callback.getCreatedUser(result);

    }
}

    @Override
public void getCreatedUser(User user) {
    // TODO Auto-generated method stub
    //Log.e("USERNAME", user.getUser_name()); 

}