<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:orientation="vertical"
        android:padding="30dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:drawableLeft="@mipmap/ic_launcher"
            android:text="QQ"
            android:textSize="50sp"/>

        <EditText
            android:id="@+id/et_account"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="30dp"
            android:hint="QQ号/手机号/邮箱"/>

        <EditText
            android:id="@+id/et_password"
            android:layout_width="match_parent"
            android:layout_height="66dp"
            android:hint="密码" />

        <Button
            android:id="@+id/bt_login"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="登录"
            android:textSize="20sp"/>

        <RelativeLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="10dp">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="忘记密码？"
                android:textColor="#00aaff"
                android:textSize="18sp"/>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="新用户注册"
                android:textColor="#00aaff"
                android:layout_alignParentRight="true"/>

        </RelativeLayout>

    </LinearLayout>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="登录即代表阅读并同意阅读条款"
        android:textSize="20sp"
        android:textColor="#F44336"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="100dp"/>

</RelativeLayout>

package com.xrj.qqlogindemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

import java.io.File;
import java.io.FileOutputStream;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private EditText mAccount;
    private EditText mPassword;
    private Button mLogin;

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

        //找到控件
        initView();
        //设置点击事件
        initListener();
    }

    private void initView() {
         mAccount = (EditText)this.findViewById(R.id.et_account);
         mPassword = (EditText)this.findViewById(R.id.et_password);
         mLogin = (Button)this.findViewById(R.id.bt_login);
    }

    private void initListener() {
        mLogin.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Log.d(TAG,"点击了登录按钮...");
                //拿到界面上的内容
                handleLoginEvent(v);
            }
        });
    }

    private void handleLoginEvent(View v) {
        String accountText = mAccount.getText().toString();
        String passwordText = mPassword.getText().toString();
        //把账号密码保存起来
        saveUserInfo(accountText,passwordText);
    }

    private void saveUserInfo(String accountTet,String passwordText) {
        Log.d(TAG,"保存用户信息");
        try {
        File file = new File("info.text");
        if(!file.exists()) {
            file.createNewFile();
        }
            FileOutputStream fos = new FileOutputStream(file);
            fos.write((accountTet + "***" + passwordText).getBytes());
            fos.close();
        }catch (Exception e) {
            e.printStackTrace();
        }
    }
}