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我正在尝试做我认为在我的服务器上对用户进行身份验证的相当简单的任务。我使用 AsyncTask 作为我的 Activity 的私有子类，但是当我在验证后尝试填充用户对象时，它一直将其设置为 null。导致这种情况的 onPostExecute() 方法的调用方式有什么奇怪的吗？我最初将 AsyncTask 作为自己的类，但遇到了同样的问题，所以我尝试使用私有子类来解决这个问题。有什么帮助吗？谢谢。

这是我的代码：

public class Testing extends Activity {

    private User user;

    public User getUser() {
        return this.user;
    }

    public void setUser(User value) {
        this.user = value;
    }

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final ImageView iconImage = (ImageView) this.findViewById(R.id.image);
        final Button testButton = (Button) this.findViewById(R.id.testButton);
        final TextView text = (TextView) this.findViewById(R.id.text);
        iconImage.setImageResource(R.drawable.logo_real);
        testButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                LoginTask loginTask = (LoginTask) new LoginTask().execute(new Void[0]);
                text.setText(user.getFormattedFullName());
            }
        });
    }

    private class LoginTask extends AsyncTask<Void, Void, User> {

        public LoginTask() {
        }

        protected User doInBackground(Void... params) {
            User newUser = new User();
            try {
                System.out.println("testing task");
                HttpClient client = new DefaultHttpClient();
                HttpGet request = new HttpGet("http://10.0.2.2:8080/Dugout/androidLogin?LOGIN_ID=test@gmail.com&PASSWORD=password");
                HttpResponse response = client.execute(request);
                HttpEntity entity = response.getEntity();
                InputStream is = entity.getContent();
                String message = "";
                String inputLine = "";
                BufferedReader bf = new BufferedReader(new InputStreamReader(is));
                while ((inputLine = bf.readLine()) != null) message+=inputLine;
                JSONObject returnedUser = new JSONObject(message);
                int userId = returnedUser.getInt("userId");
                boolean loginSuccess = returnedUser.getBoolean("login_success");
                String firstName = returnedUser.getString("firstName");
                String lastName = returnedUser.getString("lastName");
                newUser.setId(userId);
                newUser.setFirstName(firstName);
                newUser.setLastName(lastName);
                newUser.setLoginSuccess(loginSuccess);
                return newUser;
            } catch (Exception e) {
                newUser.setLoginSuccess(false);
                return newUser;
            }
        }

        protected void onPostExecute(User user) {
            setUser(user);
        }

    }

}
4

1 回答 1

2

应该

protected void onPostExecute(User user) {
    text.setText(user.getFormattedFullName());
}

您正在尝试user在它被创建之前访问AsyncTask（重点是doInBackground(..)在后台线程中运行，因此不会阻塞 UI 线程）。

于 2010-07-20T03:24:34.367 回答