Question

我需要将csv文件作为表格导入sqlite数据库。该csv文件中有很多数据。我想知道是否有一种方法可以通过Kotlin方式以编程方式导入大量数据。任何答复和评论，我将不胜感激。

{编辑} 我试图打开一个csv文件，但显示“打开失败”，但是logcat中没有显示错误。我不知道我在哪里犯了错误。这是我尝试的代码。

DatabaseHelper类

[{'N': 0, 'LT': 50, 'DATE': 2001}, {'N': 2, 'LT': 0, 'DATE': 2018}, {'N': 1, 'LT': 40, 'DATE': 2019}]

MainActivity类

class DataBaseHelper(val context: Context) : SQLiteOpenHelper(context, DATABASE_NAME, null, DATABASE_VERSION) {

companion object{

    private val DATABASE_NAME = "CSV2SQL"
    private val DATABASE_VERSION = 1

    private val TABLE_NAME = "table1"
    private val COL_ID = "Id"
    private val COL_COMPANY = "Company"
    private val COL_PRODUCT = "Product"
    private val COL_PRICE = "Price"
}
    override fun onCreate(db: SQLiteDatabase) {
        val CREATE_PRODUCTS_TABLE = ("CREATE TABLE " +
                TABLE_NAME + "("
                + COL_ID + " INTEGER PRIMARY KEY," +
                COL_COMPANY + " TEXT" +
                COL_PRODUCT + "TEXT" +
                COL_PRICE + "TEXT" +")")
        db.execSQL(CREATE_PRODUCTS_TABLE)
    }

    override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME)
        onCreate(db)
    }

    fun getAllProducts(): java.util.ArrayList<HashMap<String, String>> {
        val proList: java.util.ArrayList<HashMap<String, String>>
        proList = java.util.ArrayList()
        val selectQuery = "SELECT  * FROM $TABLE_NAME"
        val db = this.writableDatabase
        val cursor = db.rawQuery(selectQuery, null)
        if (cursor.moveToFirst()) {
            do {
                //Id, Company,Name,Price
                val map = HashMap<String, String>()
                map["Id"] = cursor.getString(0)
                map["Company"] = cursor.getString(1)
                map["Name"] = cursor.getString(2)
                map["Price"] = cursor.getString(3)
                proList.add(map)
            } while (cursor.moveToNext())
        }

        return proList
    }



  }

这是错误消息， Open Failed

Answer 1

将“读取文本类”的使用从“ FileReader”更改为“ InputStreamReader”。

class MainActivity : ListActivity() {

internal lateinit var lbl: TextView
internal lateinit var db: DataBaseHelper
internal lateinit var btnimport: Button
internal lateinit var lv: ListView
internal lateinit var myList: ArrayList<HashMap<String, String>>
val requestcode = 1

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    db = DataBaseHelper(this)
    lbl = TextView(this)
    lbl = findViewById<TextView>(R.id.txtresulttext)
    val mas = findViewById<Button>(R.id.btnupload)
    lv = getListView()



    mas.setOnClickListener  {
        val fileintent = Intent(Intent.ACTION_GET_CONTENT)
        fileintent.type = "text/csv"
        try {
            startActivityForResult(fileintent, requestcode)
        } catch (e: ActivityNotFoundException) {
            lbl.text = "No activity can handle picking a file. Showing alternatives."
        }
    }
    myList = db.getAllProducts()
    if (myList.size != 0) {
        val lv = getListView()
        var array = arrayOf("Company", "Product", "Price")
        val adapter = SimpleAdapter(this,myList,
            R.layout.v, array,intArrayOf(R.id.txtproductcompany, R.id.txtproductname, R.id.txtproductprice))
        setListAdapter(adapter)
        lbl.text = ""
    }

}

override fun  onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    if (data == null)
        return
        if (requestCode <= requestcode){
        val filepath = data.data!!.path
            println(filepath)
            val inputStream = FileInputStream(filepath)//String? to InputString
            println(inputStream)
            val db = db.getWritableDatabase()
        val tableName = "table1"
        db.execSQL("delete from $tableName")
        try {
            println("gg")
            if (resultCode == Activity.RESULT_OK) {
                try {
                    val file = InputStreamReader(inputStream)//use InputStreamReader

                    val buffer = BufferedReader(file)
                    val contentValues = ContentValues()
                    db.beginTransaction()
                    while (true){
                        val line = buffer.readLine()
                        if(line==null) break
                        val str = line.split(",".toRegex(), 3)
                            .toTypedArray()  

                        val Company = str[0].toString()
                        val Product = str[1].toString()
                        val Price = str[2].toString()

                        contentValues.put("Company", Company)
                        contentValues.put("Product", Product)
                        contentValues.put("Price", Price)
                        db.insert(tableName, null, contentValues)

                        lbl.text = "Successfully Updated Database."
                    }

                    db.setTransactionSuccessful()
                    db.endTransaction()
                } catch (e: IOException) {
                    if (db.inTransaction())
                        db.endTransaction()
                    val d = Dialog(this)
                    d.setTitle(e.message.toString() + "first")
                    d.show()
                }

            } else {
                if (db.inTransaction())
                    db.endTransaction()
                val d = Dialog(this)
                d.setTitle("Only CSV files allowed")
                d.show()
            }
        } catch (ex: Exception) {
            if (db.inTransaction())
                db.endTransaction()

            val d = Dialog(this)
            d.setTitle(ex.message.toString() + "second")
            d.show()
        }

    }
    myList = db.getAllProducts()
    if (myList.size != 0) {
        val lv = getListView()
        var array = arrayOf("Company", "Product", "Price")
        val adapter = SimpleAdapter(this,myList,
            R.layout.v, array,intArrayOf(R.id.txtproductcompany, R.id.txtproductname, R.id.txtproductprice))
        setListAdapter(adapter)
        lbl.text = "Data Imported"
    }
}
}

有没有办法使用Kotlin将CSV文件导入SQLite数据库？

1 个答案: