Android共享首选项如何注册用户然后保持登录状态

Question

我是 Android Studio 的新手，我正在使用下面的代码尝试制作它，而不是总是提示用户登录，它应该 save/register第一次访问的用户，以便他们在应用程序运行时始终登录，即跳过登录。

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    // declaring variebles
    etUsername = (EditText)findViewById(R.id.etUsername);
    etPassword= (EditText)findViewById(R.id.etPassword);
    btnLogin = (Button)findViewById(R.id.btnLogin);
    etIpAddress = (EditText) findViewById(R.id.etIpAddress);

    // setting up things for login button
    btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String ipAddress = etIpAddress.getText().toString();

            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(LoginActivity.this);

            sharedPreferences.edit()
                    .putString("ip", ipAddress)
                    .apply();

            String username = etUsername.getText().toString().trim();
            String password = etPassword.getText().toString().trim();

            performLogin(username, password, ipAddress);
        }
    });
}

Answer 1

如果先前的 ip 值存在，只需签入 onCreate

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(LoginActivity.this);
    if (sharedPreferences.contains("ip")) {                 
         performLogin(username, password, sharedPreferences.getString("ip","default value here"));
    }

    //other code 
}

Android共享首选项如何注册用户然后保持登录状态

Android Shared Preference how to register user then keep logged on

android

android-studio

login

sharedpreferences

registration