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Google 开发Android MVP架构Demo深入解析

作者:itbird01

这篇文章主要为大家介绍了Google 开发Android MVP架构Demo深入解析,有需要的朋友可以借鉴参考下,希望能够有所帮助,祝大家多多进步,早日升职加薪

1.什么是MVP?

Google在2016年推出了官方的Android MVP架构Demo,本文主要分析一下官方的MVP Demo,并且借由自己的一些经验,提出一些学习过程中,遇到的问题和自己的改进、封装措施。

MVP架构已经推出很多年了,现在已经非常普及了,我在这里就不过多介绍,简单的说,它分为以下三个层次:

在刚刚接触android的时候,或者说,现在依然有很大一部分的APP开发者,在开发过程中,总是习惯在一个Activity、Fragment中几乎完成了所有的功能。例如网络请求、数据加载、业务逻辑处理、界面加载、界面动画。 后来渐渐的我们接触到了MVC、MVP各种官方的框架,懂得了模块的分离、解耦(MVC),懂得了通过依赖于抽象去分离各个模块彻底解耦(MVP)。 但是官方的MVP框架的确已经帮我们做了很多,但是依然不够,接下来,我们基于官方给的MVP框架,结合六大基本原则,去封装更加适宜于项目的MVP框架。 整体设计模式Demo代码

2.Google官方的MVP

官方Demo怎么去做的?

我们为了方便去分析,我这里简化代码,我们逐步分析,BaseView 和 BasePresenter,BaseView谷歌是这么写的(其实就是view的接口,展示view),以下样例为了理解,我简化处理了部分代码 BaseView.java

package com.itbird.design.principle.mvp.google;
/**
 * Google Demo
 * Created by itbird on 2022/2/25
 */
public interface BaseView<T> {
    //View中,设置presenter对象,使View可以持有Presenter对象引用
    void setPresenter(T presenter);
}

BasePresenter

package com.itbird.design.principle.mvp.google;
/**
 * Google Demo
 * Created by itbird on 2022/2/25
 */
public interface BasePresenter {
}

TaskDetailContract

package com.itbird.design.principle.mvp.google;
/**
 * Google Demo
 * Created by itbird on 2022/2/25
 */
public interface TaskDetailContract {
    interface View extends BaseView<Presenter> {
        //界面UI刷新方法
        void updateTextView(String s);
    }
    interface Presenter extends BasePresenter {
        void loadDataFromModel();
    }
}

TaskGoogleActivity

package com.itbird.design.principle.mvp.google;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import com.itbird.design.R;
public class TaskGoogleActivity extends AppCompatActivity implements TaskDetailContract.View {
    private static final String TAG = TaskGoogleActivity.class.getSimpleName();
    private TaskDetailContract.Presenter mPresenter;
    private TextView mTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.textview);
        Log.e(TAG, TAG + " onCreate");
        new TaskGooglePresenter(this);
    }
    @Override
    public void setPresenter(TaskDetailContract.Presenter presenter) {
        mPresenter = presenter;
    }
    @Override
    public void updateTextView(String s) {
        mTextView.setText(s);
    }
}

TaskGooglePresenter

package com.itbird.design.principle.mvp.google;
public class TaskGooglePresenter implements TaskDetailContract.Presenter {
    private static final String TAG = TaskGooglePresenter.class.getSimpleName();
    TaskDetailContract.View mView;
    public TaskGooglePresenter(TaskDetailContract.View view) {
        mView = view;
        mView.setPresenter(this);
    }
    @Override
    public void loadDataFromModel() {
        //TODO :loaddata,此处可以用model、或者进行业务操作
        //调用界面方法,进行数据刷新
        mView.updateTextView("loaddata success!!!");
    }
}

小结 我们单从设计来说, Google MVP Demo的确向我们展示了MVP的优点:

但是,但是对于我们实际开发使用来说,依然有以下几点问题:

3.V1.1 My MVP V1

基于上面提出的三点,我们去优化Google的MVP框架。 我们首先将第一点和第二点通过抽象来解决一下。 IPresenter

package com.itbird.design.principle.mvp.v1;
/**
 * 自定义MVP框架,BasePresenter
 * Created by itbird on 2022/2/25
 */
public interface IPresenter {
    /**
     * 与view班定
     *
     * @param view
     */
    void onAttach(IView view);
    /**
     * 与view解绑
     */
    void onDetach();
    /**
     * 是否与view已经班定成功
     *
     * @return
     */
    boolean isViewAttached();
    /**
     * 获取view
     * @return
     */
    IView getView();
}

IView

package com.itbird.design.principle.mvp.v1;
/**
 * 自定义MVP框架,BaseView
 * Created by itbird on 2022/2/25
 */
public interface IView {
}

接下来是借助activity生命周期,对presenter的初始化进行封装 BaseActivity

package com.itbird.design.principle.mvp.v1;
import android.app.Activity;
import android.os.Bundle;
import androidx.annotation.Nullable;
/**
 * Created by itbird on 2022/3/29
 */
public abstract class BaseActivity extends Activity implements IView {
    IPresenter mPresenter;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPresenter = createPresenter();
        if (mPresenter != null) {
            mPresenter.onAttach(this);
        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mPresenter != null) {
            mPresenter.onDetach();
            mPresenter = null;
        }
    }
    abstract IPresenter createPresenter();
}

BasePresenter

package com.itbird.design.principle.mvp.v1;
import java.lang.ref.WeakReference;
/**
 * Created by itbird on 2022/3/29
 */
public class BasePresenter<V extends IView> implements IPresenter {
    WeakReference<V> mIView;
    @Override
    public void onAttach(IView iView) {
        mIView = new WeakReference<>((V) iView);
    }
    @Override
    public void onDetach() {
        mIView = null;
    }
    @Override
    public V getView() {
        if (mIView != null) {
            mIView.get();
        }
        return null;
    }
    @Override
    public boolean isViewAttached() {
        return mIView != null && mIView.get() != null;
    }
}

4.V1.2 My MVP V2

看上图类图,我们依然发现有一些不满足的点:

1)activity中,依然需要初始化mPresenter

 @Override
    IPresenter createPresenter() {
        mTaskPresenter = new TaskMyPresenter();
        return mTaskPresenter;
    }

是否可以做到在activity中,自己像presenter中调用view一样,自己一句话getView就可以搞定

2)观察类图,其实IView、IPresenter没有必要存在,因为毕竟只是baseActivity、basePresenter的行为

所以改造如下: BasePresenter

package com.itbird.design.principle.mvp.v2;
import java.lang.ref.WeakReference;
/**
 * Created by itbird on 2022/3/29
 */
public abstract class BasePresenter<V> {
    WeakReference<V> mIView;
    public void onAttach(V iView) {
        mIView = new WeakReference<>(iView);
    }
    public void onDetach() {
        mIView = null;
    }
    public V getView() {
        if (mIView != null) {
            mIView.get();
        }
        return null;
    }
    public boolean isViewAttached() {
        return mIView != null && mIView.get() != null;
    }
}

BaseActivity

package com.itbird.design.principle.mvp.v2;
import android.app.Activity;
import android.os.Bundle;
import androidx.annotation.Nullable;
/**
 * Created by itbird on 2022/3/29
 */
public abstract class BaseActivity<V, T extends BasePresenter<V>> extends Activity {
    T mPresenter;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPresenter = initPresenter();
        if (mPresenter != null) {
            mPresenter.onAttach((V) this);
        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (mPresenter != null) {
            mPresenter.onDetach();
            mPresenter = null;
        }
    }
    public T getPresenter() {
        return mPresenter;
    }
    abstract T initPresenter();
}

此时,契约类,不再需要依赖BasePresenter/BaseView相关接口,而且View中也可以自己获取到presenter的引用了。

package com.itbird.design.principle.mvp.v2;
/**
 * my Demo
 * Created by itbird on 2022/2/25
 */
public interface TaskMyContract {
    interface View {
        //界面UI刷新方法
        void updateTextView(String s);
    }
    interface Presenter {
        void loadDataFromModel();
    }
}
package com.itbird.design.principle.mvp.v2;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import com.itbird.design.R;
public class TaskMyActivity extends BaseActivity<TaskMyContract.View, TaskMyPresenter> implements TaskMyContract.View {
    private static final String TAG = TaskMyActivity.class.getSimpleName();
    TextView mTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = findViewById(R.id.textview);
        Log.e(TAG, TAG + " onCreate");
        mPresenter.loadDataFromModel();
    }
    @Override
    TaskMyPresenter initPresenter() {
        return new TaskMyPresenter();
    }
    @Override
    public void updateTextView(String s) {
        mTextView.setText(s);
    }
}

此时的类图,是否更加明确,而且上面各个问题都已经得到了解决。

整体设计模式Demo代码

以上就是Google 开发Android MVP架构Demo深入解析的详细内容,更多关于Google Android MVP 架构的资料请关注脚本之家其它相关文章!

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