MVP 中的簡單登入示例

必需的包結構

XML activity_login

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_vertical"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin">

    <EditText
        android:id="@+id/et_login_username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="USERNAME" />

    <EditText
        android:id="@+id/et_login_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="PASSWORD" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_login_login"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginRight="4dp"
            android:layout_weight="1"
            android:text="Login" />

        <Button
            android:id="@+id/btn_login_clear"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="4dp"
            android:layout_weight="1"
            android:text="Clear" />
    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="3dp"
        android:text="correct user: mvp, mvp" />

    <ProgressBar
        android:id="@+id/progress_login"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp" />

</LinearLayout>

活動類 LoginActivity.class

public class LoginActivity extends AppCompatActivity implements ILoginView, View.OnClickListener {
    private EditText editUser;
    private EditText editPass;
    private Button   btnLogin;
    private Button   btnClear;
    private ILoginPresenter loginPresenter;
    private ProgressBar progressBar;

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

        //find view
        editUser = (EditText) this.findViewById(R.id.et_login_username);
        editPass = (EditText) this.findViewById(R.id.et_login_password);
        btnLogin = (Button) this.findViewById(R.id.btn_login_login);
        btnClear = (Button) this.findViewById(R.id.btn_login_clear);
        progressBar = (ProgressBar) this.findViewById(R.id.progress_login);

        //set listener
        btnLogin.setOnClickListener(this);
        btnClear.setOnClickListener(this);

        //init
        loginPresenter = new LoginPresenterCompl(this);
        loginPresenter.setProgressBarVisiblity(View.INVISIBLE);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btn_login_clear:
                loginPresenter.clear();
                break;
            case R.id.btn_login_login:
                loginPresenter.setProgressBarVisiblity(View.VISIBLE);
                btnLogin.setEnabled(false);
                btnClear.setEnabled(false);
                loginPresenter.doLogin(editUser.getText().toString(), editPass.getText().toString());
                break;
        }
    }

    @Override
    public void onClearText() {
        editUser.setText("");
        editPass.setText("");
    }

    @Override
    public void onLoginResult(Boolean result, int code) {
        loginPresenter.setProgressBarVisiblity(View.INVISIBLE);
        btnLogin.setEnabled(true);
        btnClear.setEnabled(true);
        if (result){
            Toast.makeText(this,"Login Success",Toast.LENGTH_SHORT).show();
        }
        else
            Toast.makeText(this,"Login Fail, code = " + code,Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }

    @Override
    public void onSetProgressBarVisibility(int visibility) {
        progressBar.setVisibility(visibility);
    }
}

建立 ILoginView 介面

從檢視資料夾下的 Presenter 建立一個 ILoginView 介面以獲取更新資訊，如下所示：

public interface ILoginView {
    public void onClearText();
    public void onLoginResult(Boolean result, int code);
    public void onSetProgressBarVisibility(int visibility);
}

建立 ILoginPresenter 介面

建立一個 ILoginPresenter 介面，以便與 LoginActivity（檢視）進行通訊，並建立 LoginPresenterCompl 類來處理登入功能並向活動報告。LoginPresenterCompl 類實現了 ILoginPresenter 介面：

ILoginPresenter.class

public interface ILoginPresenter {
    void clear();
    void doLogin(String name, String passwd);
    void setProgressBarVisiblity(int visiblity);
}

LoginPresenterCompl.class

public class LoginPresenterCompl implements ILoginPresenter {
    ILoginView iLoginView;
    IUser user;
    Handler handler;

    public LoginPresenterCompl(ILoginView iLoginView) {
        this.iLoginView = iLoginView;
        initUser();
        handler = new Handler(Looper.getMainLooper());
    }

    @Override
    public void clear() {
        iLoginView.onClearText();
    }

    @Override
    public void doLogin(String name, String passwd) {
        Boolean isLoginSuccess = true;
        final int code = user.checkUserValidity(name,passwd);
        if (code!=0) isLoginSuccess = false;
        final Boolean result = isLoginSuccess;
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                    iLoginView.onLoginResult(result, code);
            }
        }, 5000);
    }

    @Override
    public void setProgressBarVisiblity(int visiblity){
        iLoginView.onSetProgressBarVisibility(visiblity);
    }

    private void initUser(){
        user = new UserModel("mvp","mvp");
    }
}

建立 UserModel

建立一個 UserModel，就像 LoginActivity 的 Pojo 類。為 Pojo 驗證建立 IUser 介面：

UserModel.class

public class UserModel implements IUser {
String name;
String passwd;

public UserModel(String name, String passwd) {
    this.name = name;
    this.passwd = passwd;
}

@Override
public String getName() {
    return name;
}

@Override
public String getPasswd() {
    return passwd;
}

@Override
public int checkUserValidity(String name, String passwd){
    if (name==null||passwd==null||!name.equals(getName())||!passwd.equals(getPasswd())){
        return -1;
    }
    return 0;
}

IUser.class

public interface IUser {
    String getName();

    String getPasswd();

    int checkUserValidity(String name, String passwd);
}

MVP

模型 - 檢視 - 展示器（MVP）是模型 - 檢視 - 控制器（MVC）架構模式的派生。它主要用於構建使用者介面，並提供以下好處：

• 檢視與模型更加分離。Presenter 是 Model 和 View 之間的中介。
• 建立單元測試更容易。
• 通常，View 和 Presenter 之間存在一對一的對映，可以為複雜的檢視使用多個 Presenter。