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SQLite
설명
- 안드로이드는 SQLite 데이터베이스를 사용하여 데이터를 관리할 수 있다.
코드
UserDBHelper// 마지막 파라미터가 버전
// 버전값이 변경되면 onUpgrade 메소드가 호출되어 테이블을 변경하는 작업을 수행
class UserDBHelper(context: Context) : SQLiteOpenHelper(context, "Test.db", null, 1) {
override fun onCreate(db: SQLiteDatabase?) {
Log.d("DBHelper", "onCreate")
val sql = """
CREATE TABLE user (
key INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT NOT NULL,
age INTEGER NOT NULL,
weight REAL NOT NULL,
date DATE NOT NULL
)
""".trimIndent()
db?.execSQL(sql)
}
override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
Log.d("DBHelper", "onUpgrade - $oldVersion -> $newVersion")
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/writeButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="write" />
<Button
android:id="@+id/readButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="read" />
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val writeButton = findViewById<Button>(R.id.writeButton)
val readButton = findViewById<Button>(R.id.readButton)
val textView = findViewById<TextView>(R.id.textView)
writeButton.setOnClickListener {
val helper = UserDBHelper(this)
val db = helper.writableDatabase
val sql = "INSERT INTO user (name, age, weight, date) VALUES (?, ?, ?, ?)"
val date = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()).format(Date())
/*
val values = ContentValues()
values.put("name", "john")
values.put("age", 23)
values.put("weight", 56.6)
values.put("date", date)
db.insert("user", null, values)
*/
db.execSQL(sql, arrayOf("john", 23, 56.6, date))
db.execSQL(sql, arrayOf("tom", 32, 57.6, date))
db.close()
Toast.makeText(baseContext, "저장 완료", Toast.LENGTH_SHORT).show()
}
readButton.setOnClickListener {
val helper = UserDBHelper(this)
val db = helper.writableDatabase
val sql = "SELECT * FROM user"
val c = db.rawQuery(sql, null)
textView.text = ""
while (c.moveToNext()) {
val key = c.getInt(c.getColumnIndex("key"))
val name = c.getString(c.getColumnIndex("name"))
val age = c.getInt(c.getColumnIndex("age"))
val weight = c.getDouble(c.getColumnIndex("weight"))
val date = c.getString(c.getColumnIndex("date"))
textView.append("key : $key\n")
textView.append("name : $name\n")
textView.append("age : $age\n")
textView.append("weight : $weight\n")
textView.append("date : $date\n")
}
db.close()
}
}
}
참고
ContentProvider
설명
- 애플리케이션이 저장한 데이터를 다른 애플리케이션이 사용할 수 있도록 제공하는 개념
SQLite 데이터 제공 앱 코드
- 위 SQLite 예제에 이어 아래 코드 작성
class UserDBProvider : ContentProvider() {
override fun onCreate(): Boolean {
return false
}
override fun getType(uri: Uri): String? {
TODO("Not yet implemented")
}
override fun query(
uri: Uri,
projection: Array<out String>?,
selection: String?,
selectionArgs: Array<out String>?,
sortOrder: String?
): Cursor? {
val helper = UserDBHelper(context!!)
val db = helper.writableDatabase
return db.query("user", projection, selection, selectionArgs, null, null, sortOrder)
}
override fun insert(uri: Uri, values: ContentValues?): Uri? {
val helper = UserDBHelper(context!!)
val db = helper.writableDatabase
db.insert("user", null, values)
return uri
}
override fun update(
uri: Uri,
values: ContentValues?,
selection: String?,
selectionArgs: Array<out String>?
): Int {
val helper = UserDBHelper(context!!)
val db = helper.writableDatabase
return db.update("user", values, selection, selectionArgs)
}
override fun delete(uri: Uri, selection: String?, selectionArgs: Array<out String>?): Int {
val helper = UserDBHelper(context!!)
val db = helper.writableDatabase
return db.delete("user", selection, selectionArgs)
}
}
- provider 등록 필요
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android_example">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.Androidexample">
<provider
android:name=".UserDBProvider"
android:authorities="com.example.android_example.UserDBProvider"
android:enabled="true"
android:exported="true" />
<activity android:name=".MainActivity">
<intent-filter>
<!-- Entry Point -->
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
SQLite 데이터 사용 앱 코드
res/layout/activity_main.xml<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/updateButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="update" />
<Button
android:id="@+id/writeButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="write" />
<Button
android:id="@+id/readButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="read" />
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val updateButton = findViewById<Button>(R.id.updateButton)
val writeButton = findViewById<Button>(R.id.writeButton)
val readButton = findViewById<Button>(R.id.readButton)
val textView = findViewById<TextView>(R.id.textView)
updateButton.setOnClickListener {
val uri = Uri.parse("content://com.example.android_example.UserDBProvider")
val date = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()).format(Date())
val values = ContentValues()
values.put("name", "john2")
values.put("age", 26)
values.put("weight", 56.6)
values.put("date", date)
contentResolver.update(uri, values, "key = ?", arrayOf("1"))
}
writeButton.setOnClickListener {
val uri = Uri.parse("content://com.example.android_example.UserDBProvider")
val date = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault()).format(Date())
val values = ContentValues()
values.put("name", "john")
values.put("age", 23)
values.put("weight", 56.6)
values.put("date", date)
contentResolver.insert(uri, values)
}
readButton.setOnClickListener {
val uri = Uri.parse("content://com.example.android_example.UserDBProvider")
val c = contentResolver.query(uri, null, null, null, null)
if (c != null) {
textView.text = ""
while (c.moveToNext()) {
val key = c.getInt(c.getColumnIndex("key"))
val name = c.getString(c.getColumnIndex("name"))
val age = c.getInt(c.getColumnIndex("age"))
val weight = c.getDouble(c.getColumnIndex("weight"))
val date = c.getString(c.getColumnIndex("date"))
textView.append("key : $key\n")
textView.append("name : $name\n")
textView.append("age : $age\n")
textView.append("weight : $weight\n")
textView.append("date : $date\n")
}
}
}
}
}
참고
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