android开发学习

android实现简单的登录注册（未连接后台数据库）：
效果演示：

代码：
activity_register.xml：

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:background="@color/white">

    <!-- 用户名输入框 -->
    <EditText
        android:id="@+id/etUsername"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="用户名"
        android:inputType="text"
        android:layout_marginBottom="16dp"
        android:padding="12dp"
        android:background="@drawable/edittext_background"/>

    <!-- 密码输入框 -->
    <EditText
        android:id="@+id/etPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="textPassword"
        android:layout_below="@id/etUsername"
        android:layout_marginBottom="24dp"
        android:padding="12dp"
        android:background="@drawable/edittext_background"/>

    <!-- 注册按钮 -->
    <Button
        android:id="@+id/register"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="注册"
        android:layout_below="@id/etPassword"
        android:background="@color/colorPrimary"
        android:textColor="@color/white"
        android:padding="12dp"/>

    <Button
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/etPassword"
        android:layout_marginTop="89dp"
        android:background="@color/colorPrimary"
        android:padding="12dp"
        android:text="返回"
        android:textColor="@color/white" />

</RelativeLayout>

activity_login.xml：

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<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="16dp"
    android:background="@color/white">

    <!-- 用户名输入框 -->
    <EditText
        android:id="@+id/etUsername"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="用户名"
        android:inputType="text"
        android:layout_marginBottom="16dp"
        android:padding="12dp"
        android:background="@drawable/edittext_background"/>

    <!-- 密码输入框 -->
    <EditText
        android:id="@+id/etPassword"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="密码"
        android:inputType="textPassword"
        android:layout_below="@id/etUsername"
        android:layout_marginBottom="24dp"
        android:padding="12dp"
        android:background="@drawable/edittext_background"/>

    <!-- 登录按钮 -->
    <Button
        android:id="@+id/login"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="登录"
        android:layout_below="@id/etPassword"
        android:background="@color/colorPrimary"
        android:textColor="@color/white"
        android:padding="12dp"/>

    <TextView
        android:id="@+id/register"
        android:layout_width="100dp"
        android:layout_height="30dp"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="200dp"
        android:layout_marginEnd="0dp"
        android:text="还未注册？"
        android:textColor="@color/colorPrimary" />

</RelativeLayout>

activity_main.xml：

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<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

RegisterActivity：

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package com.app.login;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;


public class LoginActivity extends AppCompatActivity {

    private EditText etUsername;
    private EditText etPassword;
    private SharedPreferences sharedPreferences;

    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_login);

        //初始化控件
        etUsername = findViewById(R.id.etUsername);
        etPassword = findViewById(R.id.etPassword);
        sharedPreferences = getSharedPreferences("user",MODE_PRIVATE);

        //点击注册
        findViewById(R.id.register).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转到注册页
                Intent intent = new Intent(LoginActivity.this,RegisterActivity.class);
                startActivity(intent);
            }
        });

        findViewById(R.id.login).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = etUsername.getText().toString();
                String password = etPassword.getText().toString();

                if(TextUtils.isEmpty(username)||TextUtils.isEmpty(password)){
                    //Toast
                    Toast.makeText(LoginActivity.this, "请输入用户名或密码", Toast.LENGTH_SHORT).show();
                }else {
                    String name = sharedPreferences.getString("username", null);
                    String pwd = sharedPreferences.getString("password", null);

                    if (username.equals(name)&&password.equals(pwd)){

                        Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                        startActivity(intent);
                    }else {
                        Toast.makeText(LoginActivity.this, "用户名或密码错误", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });
    }
}

LoginActivity：

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package com.app.login;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;


public class LoginActivity extends AppCompatActivity {

    private EditText etUsername;
    private EditText etPassword;
    private SharedPreferences sharedPreferences;

    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_login);

        //初始化控件
        etUsername = findViewById(R.id.etUsername);
        etPassword = findViewById(R.id.etPassword);
        sharedPreferences = getSharedPreferences("user",MODE_PRIVATE);

        //点击注册
        findViewById(R.id.register).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //跳转到注册页
                Intent intent = new Intent(LoginActivity.this,RegisterActivity.class);
                startActivity(intent);
            }
        });

        findViewById(R.id.login).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = etUsername.getText().toString();
                String password = etPassword.getText().toString();

                if(TextUtils.isEmpty(username)||TextUtils.isEmpty(password)){
                    //Toast
                    Toast.makeText(LoginActivity.this, "请输入用户名或密码", Toast.LENGTH_SHORT).show();
                }else {
                    String name = sharedPreferences.getString("username", null);
                    String pwd = sharedPreferences.getString("password", null);

                    if (username.equals(name)&&password.equals(pwd)){

                        Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                        startActivity(intent);
                    }else {
                        Toast.makeText(LoginActivity.this, "用户名或密码错误", Toast.LENGTH_SHORT).show();
                    }
                }
            }
        });
    }
}

MainActivity：

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package com.app.login;

import android.os.Bundle;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        EdgeToEdge.enable(this);
        setContentView(R.layout.activity_main);
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main), (v, insets) -> {
            Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
            return insets;
        });
    }
}