android studio 做用户登录页面，退出登录页面，注册页面。所有代码

这里提供一个简单的例子，包含了用户登录、退出登录和注册页面的代码。请注意，这只是一个示例，实际应用中可能需要更多的代码和逻辑。

1. 用户登录页面（activity_login.xml 和 LoginActivity.java）

activity_login.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/usernameEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Username" />

    <EditText
        android:id="@+id/passwordEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Password"
        android:inputType="textPassword" />

    <Button
        android:id="@+id/loginButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Login" />

</LinearLayout>

LoginActivity.java:

public class LoginActivity extends AppCompatActivity {
    private EditText usernameEditText;
    private EditText passwordEditText;
    private Button loginButton;

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

        usernameEditText = findViewById(R.id.usernameEditText);
        passwordEditText = findViewById(R.id.passwordEditText);
        loginButton = findViewById(R.id.loginButton);

        loginButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = usernameEditText.getText().toString();
                String password = passwordEditText.getText().toString();

                // TODO: 进行登录验证
            }
        });
    }
}

2. 退出登录页面（activity_logout.xml 和 LogoutActivity.java）

activity_logout.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical"
    android:padding="16dp">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Are you sure you want to log out?" />

    <Button
        android:id="@+id/yesButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Yes" />

    <Button
        android:id="@+id/noButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="No" />

</LinearLayout>

LogoutActivity.java:

public class LogoutActivity extends AppCompatActivity {
    private Button yesButton;
    private Button noButton;

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

        yesButton = findViewById(R.id.yesButton);
        noButton = findViewById(R.id.noButton);

        yesButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO: 进行退出登录操作
                finish();
            }
        });

        noButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });
    }
}

3. 注册页面（activity_register.xml 和 RegisterActivity.java）

activity_register.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="16dp">

    <EditText
        android:id="@+id/usernameEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Username" />

    <EditText
        android:id="@+id/passwordEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Password"
        android:inputType="textPassword" />

    <EditText
        android:id="@+id/confirmPasswordEditText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Confirm Password"
        android:inputType="textPassword" />

    <Button
        android:id="@+id/registerButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Register" />

</LinearLayout>

RegisterActivity.java:

public class RegisterActivity extends AppCompatActivity {
    private EditText usernameEditText;
    private EditText passwordEditText;
    private EditText confirmPasswordEditText;
    private Button registerButton;

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

        usernameEditText = findViewById(R.id.usernameEditText);
        passwordEditText = findViewById(R.id.passwordEditText);
        confirmPasswordEditText = findViewById(R.id.confirmPasswordEditText);
        registerButton = findViewById(R.id.registerButton);

        registerButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = usernameEditText.getText().toString();
                String password = passwordEditText.getText().toString();
                String confirmPassword = confirmPasswordEditText.getText().toString();

                // TODO: 进行注册操作
            }
        });
    }
}