안드로이드 데이터베이스 실습

안드로이드 데이터베이스 실습

1. 레이아웃

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.progdv.chap09_sqlite.MainActivity">


    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <TextView
            android:id="@+id/TextView01"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="이름: " />
        
        <EditText
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="이름 입력" />


        <TextView
            android:id="@+id/TextView02"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="주소: " />

        <EditText
            android:id="@+id/addr"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="주소 입력" />
    </LinearLayout>


<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
    <Button
        android:id="@+id/add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="저장"/>
    <Button
        android:id="@+id/search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="검색"/>

</LinearLayout>

</LinearLayout>

</RelativeLayout>

2. DBHelper 클래스 생성

package com.progdv.chap09_sqlite;

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

public class DBHelper extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "mydb.db"; // 사용할 DB명
    private static final int DATABASE_VERSION = 1; // DB 버전

    public DBHelper(Context context){
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override // 테이블 생성코드
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE myTable (name TEXT, addr TEXT);");
    }

    @Override // 테이블 삭제코드
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
     db.execSQL("DROP TABLE IF EXISTS myTable;");
        onCreate(db);
    }
}

3. MainActivity 클래스

package com.progdv.chap09_sqlite;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends AppCompatActivity {
    DBHelper helper;
    SQLiteDatabase db;
    EditText edit_name, edit_addr;
    Button add, search;

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

        helper= new DBHelper(this);
        db= helper.getWritableDatabase();

        edit_name= (EditText)findViewById(R.id.name);
        edit_addr= (EditText)findViewById(R.id.addr);

        add= (Button)findViewById(R.id.add);
        search= (Button)findViewById(R.id.search);

        add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name= edit_name.getText().toString();
                String addr= edit_addr.getText().toString();

                db.execSQL("INSERT INTO myTable VALUES ('"+name+"', '"+addr+"')");

                edit_name.setText("");
                edit_addr.setText("");
            }
        });

        search = (Button)findViewById(R.id.search);
        search.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String name = edit_name.getText().toString();
                Cursor cursor = db.rawQuery("SELECT name, addr FROM myTable WHERE name='"+name+"';", null);
                edit_addr.setText("");
                while(cursor.moveToNext()){
                    String addr = cursor.getString(1);
                    edit_addr.setText(addr);
                }
            }
        });

    }
}

이름과 주소를 입력 후 저장, 이후 이름을 입력 후 검색을 누르면 주소도 자동으로 나온다.

만든 DB파일은 device monitor 창을 띄워 file explorer에서 찾을 수 있다.