Android sqlite 数据库实现登录注册功能

一个小小的demo，希望能帮到大家

1.首先创建数据库

DatabaseHelper.java

package com.example.login;

import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

import androidx.annotation.Nullable;

public class DatebaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "login.db";
    private static final int DATABASE_VERSION = 1;
    、、创建数据库
    public DatebaseHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, DATABASE_NAME, factory, DATABASE_VERSION);
    }
    //创建数据库表
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table username( id varchar(10) primary key AUTOINCREMENT, name varchar(30), password varchar(30))");
    }
    //添加数据
    public void addData(SQLiteDatabase sqLiteDatabase, String name, String password) {
        ContentValues values = new ContentValues();
        values.put("name", name);
        values.put("password", password);
        sqLiteDatabase.insert("user", null, values);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

MainActivity.java

package com.example.login;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private static final String DATABASE_NAME = "login.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "username";
    private SQLiteDatabase db;
    private Button btn_l, btn_r;
    private EditText nameText, passText;
    private Intent intent;

    public MainActivity() {
    }

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

        DatebaseHelper databaseHelper = new DatebaseHelper(MainActivity.this, DATABASE_NAME, null, DATABASE_VERSION);
        db = databaseHelper.getWritableDatabase();

        nameText = findViewById(R.id.username);
        passText = findViewById(R.id.password);

        btn_l = findViewById(R.id.login);
        btn_r = findViewById(R.id.register);

        btn_r.setOnClickListener(v -> {
            intent = new Intent(MainActivity.this, RegisterActivaty.class);
            startActivity(intent);
        });
        btn_l.setOnClickListener(new LoginListener());
    }

    private class LoginListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            String nameString = nameText.getText().toString();
            String passString = passText.getText().toString();
            if ("".equals(nameString) || "".equals(passString)) {
                Toast.makeText(MainActivity.this, "用户名或密码不能为空", Toast.LENGTH_SHORT).show();
            } else {
                isUserinfo(nameString, passString);
            }
        }
    }

    private void isUserinfo(String name, String pass) {
        String passString = pass;
        try {
            @SuppressLint("Recycle") Cursor cursor = db.query(TABLE_NAME, new String[]{"name", "password"}, "name=?", new String[]{name}, null, null, "password");
            while (cursor.moveToNext()) {
                @SuppressLint("Range") String password = cursor.getString(cursor.getColumnIndex("password"));
                cursor.close();
                if (passString.equals(password)) {
                    new AlertDialog.Builder(MainActivity.this).setTitle("正确")
                            .setMessage("成功登录").setPositiveButton("确定", (dialog, which) -> {
                                // TODO Auto-generated method stub
                                Intent a = new Intent(MainActivity.this, MainActivity.class);
                                startActivity(a);
                            }).show();
                    break;
                } else {
                    Toast.makeText(this, "用户名密码不正确", Toast.LENGTH_LONG).show();
                    break;
                }
            }
        } catch (SQLiteException e) {
            CreatTable();
        }
    }

    private void CreatTable() {
        String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_NAME
                + " (name varchar(30) primary key,password varchar(30));";
        try {
            db.execSQL(sql);
        } catch (SQLException ignored) {
        }
    }
}

注册实现 RegisterActivity.java

package com.example.login;

import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;



public class RegisterActivaty extends Activity {
    private EditText edittext1, edittext2, edittext3;
    private DatebaseHelper databaseHelper;
    private static final String DATABASE_NAME = "login.db";
    private static final int DATABASE_VERSION = 1;
    private SQLiteDatabase db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_register);
        databaseHelper = new DatebaseHelper(RegisterActivaty.this, DATABASE_NAME, null, DATABASE_VERSION);
        db = databaseHelper.getReadableDatabase();

        edittext1 = findViewById(R.id.username);
        edittext2 = findViewById(R.id.editview2);
        edittext3 = findViewById(R.id.password);

        Button button = findViewById(R.id.tijiao);
        button.setOnClickListener(v -> {
            String namestring = edittext1.getText().toString();
            String passstring = edittext2.getText().toString();
            String repassstring = edittext3.getText().toString();

            submit(namestring, passstring, repassstring);

        });
    }
    //判空
    private void submit(String namestring, String passstring, String repassstring) {
        if (TextUtils.isEmpty(namestring)) {
            Toast.makeText(this, "用户名不能为空", Toast.LENGTH_SHORT).show();
            return;
        }

        if (TextUtils.isEmpty(passstring)) {
            Toast.makeText(this, "密码不能为空", Toast.LENGTH_SHORT).show();
            return;
        }

        if (TextUtils.isEmpty(repassstring)) {
            Toast.makeText(this, "确认密码不能为空", Toast.LENGTH_SHORT).show();
            return;
        }

        if (!notexistSameName(namestring)) {
            Toast.makeText(this, "用户名已存在", Toast.LENGTH_SHORT).show();
        } else if (passstring.equals(repassstring)) {
            db.execSQL("insert into username (name,password) values(?,?)", new String[]{namestring, passstring});
            Toast.makeText(RegisterActivaty.this, "注册成功！", Toast.LENGTH_LONG).show();
            Intent b = new Intent(RegisterActivaty.this, MainActivity.class);
            startActivity(b);
        } else {
            Toast.makeText(RegisterActivaty.this, "两次密码不一致", Toast.LENGTH_LONG).show();
        }
    }
    //通过查询数据库判断用户名是否存在
    private boolean notexistSameName(String name) {
        Cursor cursor = db.query("username", new String[]{"name"}, "name = ?", new String[]{name}, null, null, null);
        if (cursor.getCount() == 0) {
            cursor.close();
            return true;
        } else {
            cursor.close();
            return false;
        }
    }

}

效果图