3.08今日总结

今天学习了连接数据库查询功能实现登录功能

package com.example.helloworld;

import static android.widget.Toast.LENGTH_SHORT;
import static com.example.helloworld.R.*;

import androidx.activity.result.contract.ActivityResultContracts;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    Button denglu = null;
    Button zhuce = null;
    String uuser, ppwd;
    EditText user, pwd;
    SQLiteDatabase db;
    int x;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(layout.activity_main);
        user = findViewById(id.user);
        pwd = findViewById(id.pwd);
        denglu=findViewById(id.denglu);
        zhuce=findViewById(id.zhuce);
    }

    public void Denglu(View view) {
        x=0;
        uuser=user.getText().toString();
        ppwd=pwd.getText().toString();
        MyDbhelper myDbhelper = new MyDbhelper(MainActivity.this, "Data.db", null, 666);
        db = myDbhelper.getWritableDatabase();
        Cursor cursor=db.query("user",new String[]{"Id","pwd"},null,null,null,null,null,null);
        cursor.moveToFirst();
        if(uuser.equals(cursor.getString(0))==true&&ppwd.equals(cursor.getString(1))==true){
            db.close();
            Toast.makeText(MainActivity.this, "登录成功",LENGTH_SHORT ).show();
            Intent intent = new Intent(MainActivity.this, ZhuyemianActivity.class);
            this.startActivity(intent);
            x=1;
        }
        while(cursor.moveToNext()){
            if(uuser.equals(cursor.getString(0))==true&&ppwd.equals(cursor.getString(1))==true){
                db.close();
                Toast.makeText(MainActivity.this, "登录成功",LENGTH_SHORT ).show();
                Intent intent = new Intent(MainActivity.this, ZhuyemianActivity.class);
                this.startActivity(intent);
                x=1;
            }
        }
        if(x==0) {

            AlertDialog alertDialog1 = new AlertDialog.Builder(this)
                    .setTitle("提示")//标题
                    .setMessage("密码错误")//内容
                    .create();
            alertDialog1.show();
            db.close();
        }

    }
    public void Zhuce(View view) {
        Intent intent = new Intent(MainActivity.this, SecondActivity.class);
        this.startActivity(intent);
    }
     class MyDbhelper extends SQLiteOpenHelper {

        public MyDbhelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
            super(context, name, factory, version);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("create table user(user_id integer primary key autoincrement,Id varchar(20),pwd varchar(20),name varchar(20),banji varchar(20),phone varchar(20))");
        }

        @Override
        public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

        }
    }
}