Android Studio如何通过结合SQLite数据库实现简单的注册，登录功能。

2024-06-04 6414阅读

第一步：创建一个活动DatabaseHelper.java；

package com.example.myapplication;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "user.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_USERS = "users";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_USERNAME = "username";
    private static final String COLUMN_PASSWORD = "password";
    private static final String COLUMN_PHONE_NUMBER = "phone_number";
    private static final String COLUMN_ADDRESS = "address";
    private static final String CREATE_TABLE_USERS =
            "CREATE TABLE " + TABLE_USERS + "(" +
                    COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    COLUMN_USERNAME + " TEXT NOT NULL UNIQUE, " +
                    COLUMN_PASSWORD + " TEXT NOT NULL, " +
                    COLUMN_PHONE_NUMBER + " TEXT, " +
                    COLUMN_ADDRESS + " TEXT" +
                    ")";
    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_USERS);
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);
        onCreate(db);
    }
    /*@SuppressLint("Range")*/
    public long insertUser(String username, String password, String phoneNumber, String address) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_USERNAME, username);
        values.put(COLUMN_PASSWORD, password);
        values.put(COLUMN_PHONE_NUMBER, phoneNumber);
        values.put(COLUMN_ADDRESS, address);
        long result = db.insert(TABLE_USERS, null, values);
        db.close();
        return result;
    }
    public boolean checkUserExist(String username) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(TABLE_USERS, new String[]{COLUMN_ID},
                COLUMN_USERNAME + "=?", new String[]{username},
                null, null, null);
        boolean exists = cursor.getCount() > 0;
        cursor.close();
        db.close();
        return exists;
    }
    public boolean checkUserExist(String username, String password) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.query(TABLE_USERS, new String[]{COLUMN_ID},
                COLUMN_USERNAME + "=? AND " + COLUMN_PASSWORD + "=?",
                new String[]{username, password},
                null, null, null);
        boolean exists = cursor.getCount() > 0;
        cursor.close();
        db.close();
        return exists;
    }
}

第二步：创建一个活动RegisterActivity.java；

package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class RegisterActivity extends AppCompatActivity {
    EditText etUsername, etPassword, etPhoneNumber, etAddress;
    Button btnRegister;
    DatabaseHelper dbHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_register);
        etUsername = findViewById(R.id.etUsername);
        etPassword = findViewById(R.id.etPassword);
        etPhoneNumber = findViewById(R.id.etPhoneNumber);
        etAddress = findViewById(R.id.etAddress);
        btnRegister = findViewById(R.id.btnRegister);
        dbHelper = new DatabaseHelper(this);
        btnRegister.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String username = etUsername.getText().toString();
                String password = etPassword.getText().toString();
                String phoneNumber = etPhoneNumber.getText().toString();
                String address = etAddress.getText().toString();
                if (TextUtils.isEmpty(username) || TextUtils.isEmpty(password)) {
                    Toast.makeText(RegisterActivity.this, "用户名和密码不能为空", Toast.LENGTH_SHORT).show();
                    return;
                }
                if (dbHelper.checkUserExist(username)) {
                    Toast.makeText(RegisterActivity.this, "该用户名已被注册", Toast.LENGTH_SHORT).show();
                    return;
                }
                long result = dbHelper.insertUser(username, password, phoneNumber, address);
                if (result != -1) {
                    Toast.makeText(RegisterActivity.this, "注册成功", Toast.LENGTH_SHORT).show();
                    Intent intent = new Intent(RegisterActivity.this, LoginActivity.class);
                    startActivity(intent);
                } else {
                    Toast.makeText(RegisterActivity.this, "注册失败", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

第三步：创建一个activity_register.xml布局文件；

第四步：创建一个活动LoginActivity.java;

该活动登录成功后，会通过代码中的（意图）Intent跳转到MainActivity.java,读者可根据自己的需求更改代码，从而改变跳转的活动文件java的位置。

import android.content.Intent;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
public class LoginActivity extends AppCompatActivity {
    EditText etUsername, etPassword;
    Button btnLogin;
    DatabaseHelper dbHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        etUsername = findViewById(R.id.etUsername);
        etPassword = findViewById(R.id.etPassword);
        btnLogin = findViewById(R.id.btnLogin);
        dbHelper = new DatabaseHelper(this);
        btnLogin.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.makeText(LoginActivity.this, "用户名和密码不能为空", Toast.LENGTH_SHORT).show();
                    return;
                }
                if (dbHelper.checkUserExist(username, password)) {
                    Toast.makeText(LoginActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                        //创建意图
                        Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                        //启动新的activity
                        startActivity(intent);
                } else {
                    Toast.makeText(LoginActivity.this, "用户名或密码不正确", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }
}

第五步：创建一个activity_login.xml布局文件；

若完成上述内容，则有下面的运行结果展示：

且注册成功后通过Intent会自动跳转到登录页面：