android的MVP模式以及接口的理解

最近看了一下Android开发的MVP模式以及接口，深有体会。 
 
如图是MVP的一种简单结构，源码来自网上的例子 
（http://blog.csdn.net/knxw0001/article/details/39637273） 
1.

package com.mvp.bean;

//用户数据
public class UserBean {
    private String mFirstName;
    private String mLastName;

    public UserBean(String firstName, String lastName) {
        // TODO Auto-generated constructor stub
        this.mFirstName = firstName;
        this.mLastName = lastName;
    }

    public String getFirstName() {
        return mFirstName;
    }

    public String getLastName() {
        return mLastName;
    }

}

2.

package com.mvp.model;

import com.mvp.bean.UserBean;

public interface IUserModel {
    void setID(int id);

    void setFirstName(String firstName);

    void setLastName(String lastName);

    UserBean load(int id);//接口中的方法没有具体实现，只是声明
}

3.

package com.mvp.model;

import android.util.SparseArray;

import com.mvp.bean.UserBean;
//用户modol继承了接口
public class UserModel implements IUserModel {

    private String mFristName;
    private String mLastName;
    private int mID;
    private SparseArray<UserBean> mUsererArray = new SparseArray<UserBean>();
//下面都是重写的接口中的方法
    @Override
    public void setID(int id) {
        // TODO Auto-generated method stub
        mID = id;
    }

    @Override
    public void setFirstName(String firstName) {
        // TODO Auto-generated method stub
        mFristName = firstName;
    }

    @Override
    public void setLastName(String lastName) {
        // TODO Auto-generated method stub
        mLastName = lastName;
        UserBean UserBean = new UserBean(mFristName, mLastName);
        mUsererArray.append(mID, UserBean);
    }

    @Override//接口方法的具体实现
    public UserBean load(int id) {
        // TODO Auto-generated method stub
        mID = id;
        UserBean userBean = mUsererArray.get(mID, new UserBean("not found",
                "not found"));
        return userBean;

    }

}

4.

package com.mvp.presenter;

import com.mvp.bean.UserBean;
import com.mvp.model.IUserModel;
import com.mvp.model.UserModel;
import com.mvp.view.IUserView;

public class UserPresenter {
    private IUserView mUserView;//这两个都是接口，通过实例化接口对象实现了“引用”，调用继承了该接口的类的方法
    private IUserModel mUserModel;

    public UserPresenter(IUserView view) {
        mUserView = view;//muserview是一个接口，不需要新建对象
        mUserModel = new UserModel();
    }

    public void saveUser(int id, String firstName, String lastName) {
        mUserModel.setID(id);
        mUserModel.setFirstName(firstName);
        mUserModel.setLastName(lastName);
    }

    public void loadUser(int id) {
        UserBean user = mUserModel.load(id);
        mUserView.setFirstName(user.getFirstName());
        mUserView.setLastName(user.getLastName());
    }
}

5.

package com.mvp.view;

public interface IUserView {
    int getID();

    String getFristName();

    String getLastName();

    void setFirstName(String firstName);

    void setLastName(String lastName);

}

6.

package com.mvp.view;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import com.mvp.R;
import com.mvp.presenter.UserPresenter;


public class UserActivity extends Activity implements OnClickListener,
        IUserView {

    private EditText mFirstNameEditText, mLastNameEditText, mIdEditText;
    private Button mSaveButton, mLoadButton;
    private UserPresenter mUserPresenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findWidgets();
        mUserPresenter = new UserPresenter(this);
        mSaveButton.setOnClickListener(this);
        mLoadButton.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        switch (v.getId()) {
        case R.id.saveButton:
            mUserPresenter.saveUser(getID(), getFristName(),
                    getLastName());
            break;
        case R.id.loadButton:
            mUserPresenter.loadUser(getID());
            break;
        default:
            break;
        }
    }

    @Override
    public void setFirstName(String firstName) {
        // TODO Auto-generated method stub
        mFirstNameEditText.setText(firstName);
    }

    @Override
    public void setLastName(String lastName) {
        // TODO Auto-generated method stub
        mLastNameEditText.setText(lastName);
    }

    @Override
    public int getID() {
        // TODO Auto-generated method stub
        return Integer.parseInt(mIdEditText.getText().toString());
    }

    @Override
    public String getFristName() {
        // TODO Auto-generated method stub
        return mFirstNameEditText.getText().toString();
    }

    @Override
    public String getLastName() {
        // TODO Auto-generated method stub
        return mLastNameEditText.getText().toString();
    }

    void findWidgets() {
        mFirstNameEditText = (EditText) findViewById(R.id.first_name_edt);
        mLastNameEditText = (EditText) findViewById(R.id.last_name_edt);
        mIdEditText = (EditText) findViewById(R.id.id_edt);

        mSaveButton = (Button) findViewById(R.id.saveButton);
        mLoadButton = (Button) findViewById(R.id.loadButton);
    }
}

代码中的注释已经说明了一切。 
需要注意的：实例化的接口对象是为了能调用继承了该接口的类的方法； 
继承接口的类必须实现接口中的所有方法，接口中的方法并不会写具体内容，只是相当于一个“声明”。 
注意到了这些，整体 架构 的逻辑就十分好理解了，希望对 Java 语法理解不深的android初学者可以好好体会一下