Android 之設(shè)計模式Mvc念赶、Mvp和Mvvm

這篇文章記錄一下Android中框架的Mvc擒抛、Mvp、Mvvm模式补疑。在面試中有很多面試官都會問到講講三種模式的運用和區(qū)別歧沪，所以自己就來總結(jié)一下自己理解的相關(guān)的內(nèi)容。
1莲组、MVC
Model（模型層）：主要是對數(shù)據(jù)相關(guān)的操作在Model層中诊胞，比如網(wǎng)絡(luò)請求、數(shù)據(jù)庫相關(guān)內(nèi)容
View（視圖層）：一般通過xml界面展示出來的與用戶交互的UI展示
Controller（控制層）：主要是進行邏輯操作的相關(guān)內(nèi)容锹杈，Android中一般activity為控制器撵孤。
實現(xiàn)：

Controller：

public class OneActivity extends BaseAcvitiy {

    private OneModel oneModel;
    private TextView textView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //View的展現(xiàn)
        setContentView(R.layout.activity_one);

        //Model
        oneModel = new OneModel();

        textView = findViewById(R.id.tv);
        textView.setOnClickListener(onClickListener);
    }

    View.OnClickListener onClickListener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            //進行邏輯調(diào)用，點擊view獲取數(shù)據(jù)操作
            oneModel.invoke(1000, oneCallBack);

        }
    };
    OneCallBack oneCallBack = new OneCallBack() {
        @Override
        public void onSuccess(String data) {
            textView.setText(data);
        }

        @Override
        public void onFial(String errorMessage) {
            textView.setText(errorMessage);
        }
    };
}

View：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="15dp"
        android:text="請求數(shù)據(jù)"
        android:textSize="24sp"/>

</android.support.constraint.ConstraintLayout>

Model:

public class OneModel {

    public void invoke(int time, OneCallBack oneCallBack) {
        setOneCallBack(oneCallBack);
        //仿網(wǎng)絡(luò)請求竭望，嘿
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //網(wǎng)絡(luò)請求狀態(tài)判斷
        if (getOneCallBack() != null) {
            switch (time) {
                case 1000:
                    getOneCallBack().onSuccess("請求成功:" +
                            "Find something you love doing and then find a way to scale it.");
                    break;
                case 3000:
                    getOneCallBack().onFial("請求超時");
                    break;
            }

        }

    }

    private OneCallBack oneCallBack;

    public OneCallBack getOneCallBack() {
        return oneCallBack;
    }

    public void setOneCallBack(OneCallBack oneCallBack) {
        this.oneCallBack = oneCallBack;
    }
}

在MVC中邪码，Activity/Fragment既充當(dāng)了控制器層，又充當(dāng)了VIew層咬清，導(dǎo)致耦合性很高闭专，如果項目的需求功能越來越多，Activity/Fragment中的代碼會越來越龐大旧烧，會導(dǎo)致難以維護和測試影钉。所以就會有了后面的MVP的架構(gòu)模式的出現(xiàn)。
2粪滤、MVP
Model（模型層）：同MVC中的Model層
View（視圖層）：同MVC中的VIew層
Presenter（控制層）：主要是進行邏輯的操作斧拍，來支持View和Model之間的交互
實現(xiàn)：

Model：

public interface IModel {
    void network(int time,TwoCallBack twoCallBack);
}
public class TwoModel implements IModel {

    @Override
    public void network(int time, TwoCallBack twoCallBack) {
        setTwoCallBack(twoCallBack);
        //仿網(wǎng)絡(luò)請求，嘿
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //網(wǎng)絡(luò)請求狀態(tài)判斷
        if (getOneCallBack() != null) {
            switch (time) {
                case 1000:
                    getOneCallBack().onSuccess("請求成功:" +
                            "Find something you love doing and then find a way to scale it.");
                    break;
                case 3000:
                    getOneCallBack().onFial("請求超時");
                    break;
            }

        }
    }
    private TwoCallBack twoCallBack;

    public TwoCallBack getOneCallBack() {
        return twoCallBack;
    }

    public void setTwoCallBack(TwoCallBack twoCallBack) {
        this.twoCallBack = twoCallBack;
    }
}

View：

public interface IView {
    void success(String data);
    void fail(String data);
}

Presenter：

public interface IPresenter {

    void init(IView iView);
    void invoke();
}
public class TwoPresenter implements IPresenter {
    private IView iView;
    private IModel iModel;

    @Override
    public void init(IView iView) {
        this.iView = iView;
        iModel = new TwoModel();
    }

    @Override
    public void invoke() {
        iModel.network(1000,twoCallBack );
    }

    TwoCallBack twoCallBack = new TwoCallBack() {
        @Override
        public void onSuccess(String data) {
            if (iView != null) {
                iView.success(data);
            }
        }

        @Override
        public void onFial(String errorMessage) {
            if (iView != null) {
                iView.fail(errorMessage);
            }
        }
    };
}

Activity調(diào)用：

public class TwoActivity extends BaseAcvitiy implements IView {

    private Button button;
    private TwoPresenter presenter;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //View
        setContentView(R.layout.activity_two);
        //Presenter初始化
        presenter = new TwoPresenter();
        presenter.init(this);

        button = findViewById(R.id.bt);
        button.setOnClickListener(onClickListener);
    }

    View.OnClickListener onClickListener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //調(diào)用邏輯實現(xiàn)
            presenter.invoke();
        }
    };

    @Override
    public void success(String data) {
        button.setText(data);
    }

    @Override
    public void fail(String errorMs) {
        button.setText(errorMs);
    }
}

在MVP模式中杖小，主要的特點是面向接口編程的肆汹。它將業(yè)務(wù)從Activity/Fragment中分離出去，把功能邏輯操作都放在了Persenter層予权，Activity/Fragment只負(fù)責(zé)視圖層的展示昂勉，VIew層和Model層沒有任何交互，降低了耦合扫腺，更便于后期項目的維護和開發(fā)岗照。

3、MVVM
Model（模型層）：同MVC中的Model層
View（視圖層）：同MVC中的VIew層
ViewModel（視圖模型層）：處理邏輯相關(guān)內(nèi)容操作

image.png

Model層：

public class ThreeModel {
    public ObservableField<String> data=new ObservableField<>();

    public void invoke(int time,IModel iModel){
        try {
            Thread.sleep(time);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        iModel.onSuccess();
    }

View層：

public class ThreeActivity extends BaseAcvitiy {

    private ActivityThreeBinding activityThreeBinding;
    private ThreeViewModel threeModel;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        activityThreeBinding = DataBindingUtil
                .setContentView(this,R.layout.activity_three);

        threeModel = new ThreeViewModel(activityThreeBinding);

        activityThreeBinding.setModel(threeModel.getData());
        activityThreeBinding.setMain(ThreeActivity.this);

    }
    public void onClickTv(View view){
       threeModel.invoke();
    }
}

xml文件：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <data>

        <variable
            name="model"
            type="com.wtt.testac.mvvm.model.ThreeModel" />
        <variable
            name="main"
            type="com.wtt.testac.mvvm.view.ThreeActivity" />
    </data>

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/tv"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@{model.data}"
            android:onClick="@{main.onClickTv}"/>

    </android.support.constraint.ConstraintLayout>
</layout>

ViewModel層：

public class ThreeViewModel {


    private ThreeModel threeModel;

    public ThreeViewModel(ActivityThreeBinding activityThreeBinding) {
        threeModel = new ThreeModel();
    }

    public ThreeModel getData() {
        threeModel.data.set("請求數(shù)據(jù)");
        return threeModel;
    }

    public void invoke() {
        threeModel.invoke(1000, iModel);
    }

    IModel iModel = new IModel() {
        @Override
        public void onSuccess() {
            threeModel.data.set("請求成功");
        }

        @Override
        public void onFial(String errorMessage) {

        }
    };
}

在MVVM中，View和Model使用DataBinding來進行雙向綁定攒至，一方的改變都會影響另一方厚者，開發(fā)者不用再去手動修改UI的數(shù)據(jù)。項目結(jié)構(gòu)更加的低耦合迫吐。

總結(jié)：這篇文章主要介紹了三種不同模式的區(qū)別和簡單的例子實現(xiàn)库菲，具體項目用什么模式可以自己針對具體情況去選擇合適的模式。文章中有任何問題志膀，和不對的地方熙宇，歡迎指出，后續(xù)會繼續(xù)完善溉浙。

Android 之設(shè)計模式Mvc、Mvp和Mvvm

Android 之設(shè)計模式Mvc勿璃、Mvp和Mvvm