我一直在测试dot42,到目前为止很棒,但我发现没有任何SQLite示例。我不确定我是否应该实现ContentProvider(如某些Android文章建议的那样),或者我是否可以使用dot42的异步/等待实现来异步执行查询并在ListView上显示结果。
有什么建议吗?
提前致谢
Roygar
答案 0 :(得分:2)
这是一个代码示例,它使用dot42的async / await实现异步检索SQLite数据库中的联系人。我省略了SQLite代码。 ContactsDatabase
继承自SQLiteOpenHelper
并实现常用方法。
using System;
using System.Threading;
using System.Threading.Tasks;
using System.Collections.Generic;
using Android.App;
using Android.Os;
using Android.Widget;
using Dot42;
using Dot42.Manifest;
[assembly: Application("SQLiteAsyncSample")]
namespace SQLiteAsyncSample
{
[Activity]
public class MainActivity : Activity
{
private ArrayAdapter<string> adapter;
ContactsDatabase database;
int i = 0;
protected override void OnCreate(Bundle savedInstance)
{
base.OnCreate(savedInstance);
SetContentView(R.Layouts.MainLayout);
ListView list = FindViewById<ListView>(R.Ids.list);
adapter = new ArrayAdapter<string>(this, Android.R.Layout.Simple_list_item_1);
list.SetAdapter(adapter);
database = new ContactsDatabase(this);
database.AddContact(new Contact("Frank", "012"));
database.AddContact(new Contact("Marco", "345"));
database.AddContact(new Contact("Hans", "678"));
database.AddContact(new Contact("Sergey", "901"));
Button addAllButton = FindViewById<Button>(R.Ids.showall);
addAllButton.Click += showAllButton_Click;
// Set the static synchronization context to the current/latest 'this'.
// This allows the code after the wait to resume on the 'current' this
// even if the Activity was recycled, e.g. due to a device rotation.
SynchronizationContext.SetSynchronizationContext(this);
}
private async void showAllButton_Click(object sender, EventArgs e)
{
List<Contact> contacts = null;
await Task.Factory.StartNew( () => {
// lengthy job
contacts = database.GetAllContacts();
}).ConfigureAwait(this);
// make sure to access the adapter from the UI thread
// so not in the anonymous delegate above
foreach (Contact contact in contacts) {
adapter.Add(contact.Name);
}
}
}
}