Android|Android Kotlin使用SQLite案例详解 AndroidKotlin使用SQLite案例详解

Kotlin使用SQLite
首先确定我们的目标，SQLite只是一种工具，我们需要掌握就是增删改查就可以，我们真正需要动脑的还是项目中的业务逻辑。我这篇文章写得比较适合新手，没用过SQLite的同学。
前期准备工作
新建一个类MyDataBaseHelper继承自SQLiteOpenHelper，代码如下：

class MyDatabaseHelper(var context: Context, name: String, version: Int) :SQLiteOpenHelper(context, name, null, version) {public var createBook="create table Book (" +"id integer primary key autoincrement," +"author text," +"price real," +"pages integer," +"name text)"override fun onCreate(db: SQLiteDatabase?) {//下面这个todo 如果不注释掉的话就会报错。//TODO("not implemented") //To change body of created functions use File | Settings | File Templates.db?.execSQL(createBook)Toast.makeText(context,"Create Successed",Toast.LENGTH_LONG).show()}override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {//TODO("not implemented") //To change body of created functions use File | Settings | File Templates.db?.execSQL("drop table if exists Book")onCreate(db)}}

对数据进行操作
操作比较简单，下面直接看代码:
Activity中

class MySQLite : AppCompatActivity() {override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_my_sqlite)val dbHelper=MyDatabaseHelper(this,"BookStore.db",1)/*** 创建表*/btnCreateDataBase.setOnClickListener {dbHelper.writableDatabase}/*** 添加数据*/btnAddData.setOnClickListener {val db=dbHelper.writableDatabaseval Values1=ContentValues().apply {//第一条数据put("name","The Da Vinci Code")put("author","Dan Broen")put("pages",454)put("price",16.96)}db.insert("Book",null,Values1)valvalues2=ContentValues().apply {//第二条数据put("name","The Lost Symbol")put("author","Dan Brown")put("pages",510)put("price",19.95)}db.insert("Book",null,values2)}btnUpdateData.setOnClickListener {val db=dbHelper.writableDatabaseval values=ContentValues()values.put("price",10.99)db.update("Book",values,"name=?", arrayOf("The Da Vinci Code"))}btnDeleteData.setOnClickListener {val db=dbHelper.writableDatabasedb.delete("Book","pages>?", arrayOf("500"))}btnQueryData.setOnClickListener {val db=dbHelper.writableDatabase//查询Book表中所有数据//这里获取到是Cursor对象val cursor=db.query("Book",null,null,null,null,null,null)if (cursor.moveToFirst()){do {val name=cursor.getString(cursor.getColumnIndex("name"))val author=cursor.getString(cursor.getColumnIndex("author"))val pages=cursor.getString(cursor.getColumnIndex("pages"))val price=cursor.getString(cursor.getColumnIndex("price"))Log.d("MainActivity","book name is $name")Log.d("MainActivity","author is $author")Log.d("MainActivity","pages is $pages")Log.d("MainActivity","price is $price")}while (cursor.moveToNext())}cursor.close()}}}

布局文件

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