我正在使用MVVM设计模式制作用户登录屏幕,但当它实现电话号码验证的逻辑时,我陷入了困境。 我读出了Rules to follow when working with mvvm (规则 4) View 中不应该有任何逻辑,甚至不应该是一个简单的 if 条件。 View 的所有逻辑都发生在 ViewModel 中。
这是我的 ViewModel 类。
public class LoginViewModel extends AndroidViewModel {
private LoginRepository loginRepository;
private HashMap<String,String> mNumberParam;
private MutableLiveData<Boolean> isValidated;
public LoginViewModel(@NonNull Application application) {
super(application);
loginRepository=LoginRepository.getInstance();
isValidated=new MutableLiveData<>();
}
public LiveData<List<OtpEnterModel.Data>> enterNumberApiHit(){
return loginRepository.enterNumberApiHit(mNumberParam);
}
public void onSubmitClick(String number){
//if mobile number not enter or wrong enter show message ,and tell the view to hide other view
if (number==null) {
Toast.makeText(getApplication(), "Invalid mobile number", Toast.LENGTH_SHORT).show();
isValidated.setValue(false);
} else {
//otherwise save mobile number in hashMap ,and tell the view to work further
isValidated.setValue(true);
saveNumberParam(number);
}
}
//to save the mobile number in hashMap with key i.e mobile_number.
private void saveNumberParam(String mobileNumber) {
//if hashMap null then initialize it
if (mNumberParam ==null) {
mNumberParam = new HashMap<>();
}
mNumberParam.put(MyConstant.MOBILE_NUMBER, mobileNumber);
}
public LiveData<Boolean> isValidated(){
return isValidated;
}
}
这是我的 View 类。
public class EnterNumber extends AppCompatActivity implements View.OnClickListener, FragmentManager.OnBackStackChangedListener {
//dataType
private Context context;
private FragmentManager manager;
private LoginViewModel loginViewModel;
//views
private EditText enterMobileEDT;
private ProgressBar progressBar;
private Button btnNumber;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_enter_number);
manager=getSupportFragmentManager();
context = EnterNumber.this;
loginViewModel= ViewModelProviders.of(this).get(LoginViewModel.class);
init();
setListener();
}
//all views initialize here
private void init() {
enterMobileEDT = findViewById(R.id.enterMobileET);
progressBar=findViewById(R.id.progressBar);
btnNumber=findViewById(R.id.btn_number);
}
//listener for views
private void setListener() {
btnNumber.setOnClickListener(this);
manager.addOnBackStackChangedListener(this);
}
//check for mobile number and send otp by hitting API
@Override
public void onClick(View v) {
if (v.getId() == R.id.btn_number) {
loginViewModel.onSubmitClick(enterMobileEDT.getText().toString());
numberValidation();
}
}
//check for editText length
public void numberValidation() {
loginViewModel.isValidated().observe(this, new Observer<Boolean>() {
@Override
public void onChanged(Boolean aBoolean) {
if(aBoolean){
loginApiHit();
}
hideShowView(aBoolean);
}
});
}
//hide and show the view based on condition
public void hideShowView(boolean wantToShowProgress) {
if(!wantToShowProgress){
progressBar.setVisibility(View.INVISIBLE);
btnNumber.setEnabled(true);
}else {
progressBar.setVisibility(View.VISIBLE);
btnNumber.setEnabled(false);
}
}
}
如何将所有 if/else 条件从 View 移至 ViewModel?
最佳答案
问题
How Can I move all if/else condition from View to ViewModel?
- 建议您删除 View 中的所有业务逻辑。
- View 仅具有用于更新耦合 ViewModel 数据 (LiveData) 的 UI 的代码,可以通过
ViewDataBininding
库减少这些代码。 - 最后,View 只有与设置
ViewDataBinding
和ViewModel
相关的代码。
View 模型
public class LoginViewModel extends AndroidViewModel {
...
private MutableLiveData<String> _email = new MutableLiveData<>(); // is binded some UI such as EditText..
LiveData<Boolean> emailValidate = Transformations.map(_email, this::emailValidate);
private boolean emailValidate(String email) {
return true; // implements email validation logic
}
...
}
查看
...
@Override
public void onCreate(@Nullable Bundle savedInstanceState, @Nullable PersistableBundle persistentState) {
super.onCreate(savedInstanceState, persistentState);
LoginViewModel loginViewModel= ViewModelProviders.of(this).get(LoginViewModel.class);
subscribe(loginViewModel);
}
private void subscribe(LoginViewModel loginViewModel) {
loginViewModel.emailValidate.observe(this, this::setEmailValidateLayout);
// You shouldn't implement observing in the onClick event. Overlapping observers problem.
}
private void setEmailValidateLayout(boolean validate) {
progressBar.setVisibility(validate ? View.VISIBLE : View.INVISIBLE);
btnNumber.setEnabled(validate);
}
...
关于java - 使用 mvvm 时将业务逻辑放在哪里,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/57966523/