[maro/#33] feat :: SongDao, SongDatabase 추가

UMC_6th/app/src/main/java/com/example/umc_6th/SongDatabase.kt

@@ -0,0 +1,30 @@
+package com.example.umc_6th
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+
+@Database(entities = [Song::class], version = 1)
+abstract class SongDatabase: RoomDatabase() {
+    abstract fun songDao(): SongDao
+
+    companion object {
+        private var instance: SongDatabase? = null
+
+        @Synchronized
+        fun getInstance(context: Context): SongDatabase? {
+            if (instance == null) {
+                synchronized(SongDatabase::class){
+                    instance = Room.databaseBuilder(
+                        context.applicationContext,
+                        SongDatabase::class.java,
+                        "song-database" // 다른 데이터 베이스랑 이름이 겹치지 않도록 주의
+                    ).allowMainThreadQueries().build() // 편의상 메인 쓰레드에서 처리하게 한다.
+                }
+            }
+
+            return instance
+        }
+    }
+}