MVP框架（登录例子实现）

1.首先开启权限

<uses-permission android:name="android.permission.INTERNET"/>

2.xml代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".activity.MainActivity"
    android:orientation="vertical">
    <EditText
        android:id="@+id/editText1"
        android:hint="账号"
        android:textSize="18sp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <EditText
        android:id="@+id/editText2"
        android:hint="密码"
        android:textSize="18sp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <CheckBox
            android:id="@+id/checkBox1"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:textSize="18sp"
            android:text="记住密码" />
        <CheckBox
            android:id="@+id/checkBox2"
            android:layout_width="0dp"
            android:layout_weight="1"
            android:layout_height="wrap_content"
            android:textSize="18sp"
            android:text="自动登录" />
    </LinearLayout>
    <Button
        android:id="@+id/button1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="登录"
        android:textSize="18sp"/>



</LinearLayout>

3.V层（MainActivity）

package com.example.zhoukao.activity;

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

import com.example.zhoukao.R;
import com.example.zhoukao.bean.User;
import com.example.zhoukao.core.IBaseView;
import com.example.zhoukao.presenter.MyPresenter;


public class MainActivity extends AppCompatActivity implements IBaseView {

    private CheckBox checkBox1;
    private CheckBox checkBox2;
    private Button button1;
    private EditText editText1;
    private EditText editText2;
    private MyPresenter myPresenter;
    private SharedPreferences sp;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        checkBox1 = findViewById(R.id.checkBox1);
        checkBox2 = findViewById(R.id.checkBox2);
        button1 = findViewById(R.id.button1);
        editText1 = findViewById(R.id.editText1);
        editText2 = findViewById(R.id.editText2);
        myPresenter = new MyPresenter(this);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = editText1.getText().toString();
                String pwd = editText2.getText().toString();
                myPresenter.login(name,pwd);
            }
        });
        sp = getSharedPreferences("login",MODE_PRIVATE);
        if(sp.getBoolean("c1",false)){
            editText1.setText(sp.getString("name",""));
            editText2.setText(sp.getString("pwd",""));
            checkBox1.setChecked(true);
        }
        if(sp.getBoolean("c2",false)){
            startActivity(new Intent(MainActivity.this,TwoActivity.class));
            finish();
        }

    }

    @Override
    public void success(User user) {
        Toast.makeText(this, ""+user.getMsg(), Toast.LENGTH_SHORT).show();
        startActivity(new Intent(MainActivity.this,TwoActivity.class));
        SharedPreferences.Editor editor = sp.edit();
        String name = editText1.getText().toString();
        String pwd = editText2.getText().toString();
        editor.putString("name",name);
        editor.putString("pwd",pwd);
        editor.putBoolean("c1",checkBox1.isChecked());
        editor.putBoolean("c2",checkBox2.isChecked());
        editor.commit();

    }

    @Override
    public void fail(String info) {
        Toast.makeText(this, ""+info, Toast.LENGTH_SHORT).show();
    }

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

P层

package com.example.zhoukao.presenter;

import android.os.Handler;
import android.os.Message;

import com.example.zhoukao.bean.User;
import com.example.zhoukao.core.IBaseView;
import com.example.zhoukao.model.MyModel;

public class MyPresenter {
    IBaseView iBaseView;

    public MyPresenter(IBaseView iBaseView) {
        this.iBaseView = iBaseView;
    }
    public MyPresenter(){
        this.iBaseView = null;
    }

    Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            User user = (User) msg.obj;
            if(user.getCode().equals("0")){
                iBaseView.success(user);
            }else{
                iBaseView.fail(user.getMsg());
            }
        }
    };
    public void login(final String name, final String pwd) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                User user = MyModel.getString(name,pwd);
                Message message = handler.obtainMessage();
                message.obj = user;
                handler.sendMessage(message);
            }
        }).start();
    }
}

M层

package com.example.zhoukao.model;

import com.example.zhoukao.bean.User;
import com.google.gson.Gson;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MyModel {
    public static User getString(String name, String pwd) {
        String urlString = "http://www.zhaoapi.cn/user/login?mobile=" + name + "&password=" + pwd;
        try {
            URL url = new URL(urlString);
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            InputStream inputStream = urlConnection.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            String str1 = "";
            String str2 = "";
            while ((str1 = reader.readLine())!= null){
                str2 += str1;
            }
            Gson gson = new Gson();
            User user = gson.fromJson(str2, User.class);
            return  user;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

自定义接口

package com.example.zhoukao.core;

import com.example.zhoukao.bean.User;

public interface IBaseView {
    void success(User user);
    void fail(String info);
}