如何使用 Async Task 执行数据库操作 [英] How to perform database operations using Async Task
问题描述
在谷歌搜索解决方案后,我的应用程序在执行数据库操作时卡住了,建议我使用 AsyncTask 以便主线程不会被阻塞.
My application is getting stuck while performing database operation after googling for solutions it was suggested that I use AsyncTask so that main thread doesn't get blocked.
我创建了单独的类并扩展了 SQLiteOpenHelper 并实现了OnCreate"和OnUpgrade"方法.但是要实现 AsyncTask,我需要扩展AsyncTask".现在我的问题是我已经扩展了一个类,我不能为同一个类扩展另一个类.
I have created seperate class and extended SQLiteOpenHelper and implemented "OnCreate" and "OnUpgrade" method. But to implement AsyncTask I need to extend "AsyncTask". Now my issue here is that I have already extended one class and I can't extend another class for the same class.
我的代码是这样的.
import android.content.Context;
import android.database.Cursor;
import android.database.DatabaseErrorHandler;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.Toast;
import com.example.project.R;
public class Database extends SQLiteOpenHelper{
static final String dbname="Project";
static final int dbversion=1;
TableA r=new TableA();
SQLiteDatabase db;
private Context Context;
public Database(Context context) {
super(context, dbname, null, dbversion);
try{
db=getWritableDatabase();
// TODO Auto-generated constructor stub
if (db.isOpen()){
System.out.println("Database is opened");
}
else{
System.out.println("Database is not opened");
}
}
catch(Exception e){
Log.e(dbname, e.getMessage());
}
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
try{
db.beginTransaction();
db.execSQL(r.r_Table);
db.insert(r.Tablename, null, r.insertdata());
db.setTransactionSuccessful();
retrivedata();
}
catch(Exception e){
android.util.Log.e(r.Tablename, e.getMessage());
}
finally{
db.endTransaction();
}
}//
谁能建议我如何在 AsyncTask 中使用 SQLiteOpenHelper 执行数据库操作.
Can anyone suggest how I can perform database operations with SQLiteOpenHelper within an AsyncTask.
谢谢湿婆
推荐答案
在你的Actvity
中添加以下代码,做需要的修改,
In your Actvity
add the following code, do the required changes,
private class GetContacts extends AsyncTask<Object, Object, Cursor> {
DatabaseConnector dbConnector = new DatabaseConnector(
getApplicationContext());
@Override
protected Cursor doInBackground(Object... params) {
dbConnector.open();
if (dbConnector.getAllValues() != null) {
return dbConnector.getAllValues();
} else
return null;
}
@Override
protected void onPostExecute(Cursor result) {
if (result != null) {
conAdapter.changeCursor(result); // set the adapter's Cursor
dbConnector.close();
}
}
}
通过new GetContacts().execute((Object[]) null);
这篇关于如何使用 Async Task 执行数据库操作的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!