Android--再探MVP模式

1，上一篇我们已经了解了大致的MVP模式，下面再通过这个登录功能的例子 ，我们能过更加容易的掌握MVP模式，再来补充一些闲外话：MVP 是 MVC 的变种，其实是一种升级。要说 MVP 就要说说 MVC，在 MVC 中 Activity 其实是 View层级，但是通常在使用中 Activity即是View也是Controller，并没有将 View层 和 Controller层 进行分离， 耦合度大大提高，非常不利于项目的管理。MVP 把 Activity 中的 UI逻辑 抽象成 View接口，把 业务逻辑 抽象成 Presenter接口，Model类 还是原来的 Model。

2，先来看一下我们这次的简单的布局文件，两个输入框和两个按钮

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.qianmo.mvpdemo.MainActivity">

    <EditText
        android:id="@+id/editText_user"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:hint="Username"/>

    <EditText
        android:id="@+id/editText_pass"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignEnd="@+id/editText_user"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignRight="@+id/editText_user"
        android:layout_below="@+id/editText_user"
        android:hint="Password"/>

    <Button
        android:id="@+id/button_clean"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/editText_pass"
        android:layout_marginLeft="35dp"
        android:layout_marginStart="35dp"
        android:layout_marginTop="69dp"
        android:text="clean"/>

    <Button
        android:id="@+id/button_login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/button_clean"
        android:layout_alignEnd="@+id/editText_pass"
        android:layout_alignRight="@+id/editText_pass"
        android:layout_marginEnd="42dp"
        android:layout_marginRight="42dp"
        android:text="Login"/>
</RelativeLayout>

　　在创建我们的功能类LoginContract,包含这个登录功能的，view、presenter、model类，这里推荐使用MVPHelper插件，一步搞定

package com.qianmo.mvpdemo.contract;

/**
 * Created by wangjitao on 2016/10/31 0031.
 * 用于实现登录功能的实现类
 */
public class LoginContract {

    public interface View {

        public void doClean();

        public void loginResult(boolean isSuccess, String messing);
    }

    public interface Presenter {
        public void clean();

        public void doLogin(String username, String password);
    }

    public interface Model {

    }

}

　model实现类

package com.qianmo.mvpdemo.model;

import com.qianmo.mvpdemo.contract.LoginContract;

/**
 * Created by MVPHelper on 2016/10/31
 */

public class LoginModelImpl implements LoginContract.Model {

    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

persenter的实现类

package com.qianmo.mvpdemo.presenter;

import com.qianmo.mvpdemo.MainActivity;
import com.qianmo.mvpdemo.contract.LoginContract;

/**
 * Created by MVPHelper on 2016/10/31
 */

public class LoginPresenterImpl implements LoginContract.Presenter {

    private MainActivity mainActivity;

    public LoginPresenterImpl(MainActivity mainActivity) {
        this.mainActivity = mainActivity;
    }

    @Override
    public void clean() {
        mainActivity.doClean();
    }

    @Override
    public void doLogin(String username, String password) {
        if ("wangjitao".equals(username) && "123".equals(password)) {
            mainActivity.loginResult(true, "user:" + username + ",pass:" + password);
        }else {
            mainActivity.loginResult(false, "user:" + username + ",pass:" + password);
        }
    }
}

　最后是我们的UI，也就是我们的Activity

package com.qianmo.mvpdemo;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.qianmo.mvpdemo.contract.LoginContract;
import com.qianmo.mvpdemo.presenter.LoginPresenterImpl;

public class MainActivity extends AppCompatActivity implements LoginContract.View, View.OnClickListener {
    private EditText et_username;
    private EditText et_password;
    private Button btn_clean;
    private Button btn_login;
    private LoginPresenterImpl mLoginPresenter;

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

        et_username = (EditText) findViewById(R.id.editText_user);
        et_password = (EditText) findViewById(R.id.editText_pass);

        btn_clean = (Button) findViewById(R.id.button_clean);
        btn_login = (Button) findViewById(R.id.button_login);
        mLoginPresenter = new LoginPresenterImpl(this);

        btn_login.setOnClickListener(this);
        btn_clean.setOnClickListener(this);
    }

    @Override
    public void doClean() {
        et_username.setText("");
        et_password.setText("");
    }

    @Override
    public void loginResult(boolean isSuccess, String messing) {

        if (isSuccess) {
            Toast.makeText(MainActivity.this, "登陆成功：" + messing, Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(MainActivity.this, "登陆失败", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.button_clean:
                mLoginPresenter.clean();
                break;
            case R.id.button_login:
                mLoginPresenter.doLogin(et_username.getText().toString(), et_password.getText().toString());
                break;
        }
    }
}

　　ok，这样的话  感觉一会儿就写出MVP的小demo了