在Android中正确检查用户是否已登录。

huangapple
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英文:

Correctly check if user is logged in. Android

问题

在我的MainActivity.java中，我使用Retrofit从服务器进行身份验证，并且使用令牌API进行身份验证：

  1. apiInterface = ApiClient.getClient().create(ApiInterface.class);
  3. User user = SharedPreferencesHelper.getUser(MainActivity.this);
  5. if (user.getToken() == null) {
  6.     Intent login = new Intent(MainActivity.this, LoginActivity.class);
  7.     startActivity(login);
  8. } else {
  9.     setContentView(R.layout.activity_main);
  10.     buildMain();
  11. }

在我的LoginActivity.java中，我有一个问题，用户登录后显示一个空白页面，而不是预期的activity_main.xml，但当我关闭应用并重新打开时，它会像预期的那样直接跳转到activity_main.xml。是否有原因导致登录后没有像预期的那样跳转到activity_main？

英文:

I have my login setup like this, I use retrofit to authenticate from the server and I'm using a token api authentication:

In the MainActivity.java method onCreate

  1. apiInterface = ApiClient.getClient().create(ApiInterface.class);
  3. User user = SharedPreferencesHelper.getUser(MainActivity.this);
  5. if (user.getToken() == null) {
  6.     Intent login = new Intent(MainActivity.this, LoginActivity.class);
  7.     startActivity(login);
  8. } else {
  9.     setContentView(R.layout.activity_main);
  10.     buildMain();
  11. }

In the LoginActivity.java method on create (I'll summarize, the code is quite long)

  1. loginbtn.setOnClickListener(new View.OnClickListener() {
  2.     @Override
  3.     public void onClick(View v) {
  4.         //get login ingo
  6.         Login login = new Login(scardI, passwordI, device_name);
  8.         Call<User> call = apiInterface.LoginUser(login);
  10.         call.enqueue(new Callback<User>() {
  11.             @Override
  12.             public void onResponse(Call<User> call, Response<User> response) {
  13.                 if (response.isSuccessful()) {
  14.                     User user = response.body();
  15.                     //save user info into SharedPreferences
  16.                     SharedPreferencesHelper.setUser(LoginActivity.this, user);
  17.                     
  18.                     //check if user saved correctly by getting the user token
  19.                     if (SharedPreferencesHelper.getUserToken(LoginActivity.this) != null) {
  20.                         finish();
  21.                     }
  22.                 } else {
  23.                     //show error message
  24.                 }
  25.             }
  26.             @Override
  27.             public void onFailure(Call<User> call, Throwable t) {
  28.                 //show error message
  29.             }
  30.         });
  31.     }
  32. });

I'm having an issue, after the user logs in a blank page is displayed instead of the activity_main.xml however when I close the app and reopen it it takes me straight to the activity_main.xml as expected. Is there a reason that after the login it doesn't take me to the activity_main like expected.

答案1

得分: 1

  1. 如果响应成功，缺少跳转至 MainActivity.java 的意图。由于调用了 finish() 方法，所以显示为空白屏幕。
  3. if (response.isSuccessful()) {
  4.     User user = response.body();
  5.     SharedPreferencesHelper.setUser(LoginActivity.this, user);
  6.     if (SharedPreferencesHelper.getUserToken(LoginActivity.this) != null) {
  7.         Intent i = new Intent(this, MainActivity.class);
  8.         i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
  9.         startActivity(i);
  10.     }
  11. }
英文:

An intent to MainActivity.java is missing on success. A blank screen is displayed because finish() is called.

  1.  if (response.isSuccessful()) {
  2.      User user = response.body();
  3.      SharedPreferencesHelper.setUser(LoginActivity.this, user);
  4.       if (SharedPreferencesHelper.getUserToken(LoginActivity.this) != null){
  5.        Intent i = new Intent(this, MainActivity.class);
  6.        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK)
  7.        startActivity(i);
  8. }
  9.                     
  10. }

huangapple
  • 本文由 发表于 2020年4月6日 23:02:16
  • 转载请务必保留本文链接：https://java.coder-hub.com/61062756.html
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