C# 如何创建背景线程
我目前正在开发一款移动android应用程序。此应用程序在加载时间上遇到的主要问题是Webservice json字符串,在当前阶段加载该字符串花费的时间太长,有时会导致应用程序强制关闭(暂停时间太长) Splash->MainActivity->HomeActivity这就是应用程序的启动方式 首先,我们显示一个Splash,然后运行MainActivity,它由以下代码组成:C# 如何创建背景线程,c#,android,json,multithreading,C#,Android,Json,Multithreading,我目前正在开发一款移动android应用程序。此应用程序在加载时间上遇到的主要问题是Webservice json字符串,在当前阶段加载该字符串花费的时间太长,有时会导致应用程序强制关闭(暂停时间太长) Splash->MainActivity->HomeActivity这就是应用程序的启动方式 首先,我们显示一个Splash,然后运行MainActivity,它由以下代码组成: public class HomeActivity : Activity { NewsObject[] n
public class HomeActivity : Activity
{
NewsObject[] news;
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
SetContentView (Resource.Layout.Main);
var request = HttpWebRequest.Create(string.Format(@"http://rapstation.com/webservice.php"));
request.ContentType = "application/json";
request.Method = "GET";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
if (response.StatusCode != HttpStatusCode.OK)
Console.Out.WriteLine("Error fetching data. Server returned status code: {0}", response.StatusCode);
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
var content = reader.ReadToEnd();
if(string.IsNullOrWhiteSpace(content)) {
Console.Out.WriteLine("Response contained empty body...");
Toast toast = Toast.MakeText (this, "No Connection to server, Application will now close", ToastLength.Short);
toast.Show ();
}
else {
news = JsonConvert.DeserializeObject<NewsObject[]>(content);
}
}
Console.Out.WriteLine ("Now: \r\n {0}", news[0].title);
}
var list = FindViewById<ListView> (Resource.Id.list);
list.Adapter = new HomeScreenAdapter (this, news);
list.ItemClick += OnListItemClick;
var Listen = FindViewById<Button> (Resource.Id.btnListen);
var Shows = FindViewById<Button> (Resource.Id.btnShows);
Listen.Click += (sender, e) => {
var second = new Intent (this, typeof(RadioActivity));
StartActivity (second);
};
Shows.Click += (sender, e) => {
var second = new Intent (this, typeof(ShowsActivity));
StartActivity (second);
};
}
protected void OnListItemClick(object sender, AdapterView.ItemClickEventArgs e)
{
var listView = sender as ListView;
var t = news[e.Position];
var second = new Intent (this, typeof(NewsActivity));
second.PutExtra ("newsTitle", t.title);
second.PutExtra ("newsBody", t.body);
second.PutExtra ("newsImage", t.image);
second.PutExtra ("newsCaption", t.caption);
StartActivity (second);
Console.WriteLine("Clicked on " + t.title);
}
}
公共类家庭活动:活动
{
新闻对象[]新闻;
创建时受保护的覆盖无效(捆绑包)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.Main);
var request=HttpWebRequest.Create(string.Format)(@)http://rapstation.com/webservice.php"));
request.ContentType=“application/json”;
request.Method=“GET”;
使用(HttpWebResponse=request.GetResponse()作为HttpWebResponse)
{
if(response.StatusCode!=HttpStatusCode.OK)
Console.Out.WriteLine(“获取数据时出错。服务器返回状态代码:{0}”,response.StatusCode);
使用(StreamReader=newstreamreader(response.GetResponseStream())
{
var content=reader.ReadToEnd();
if(string.IsNullOrWhiteSpace(content)){
Console.Out.WriteLine(“响应包含空体…”);
Toast Toast=Toast.MakeText(这是“没有连接到服务器,应用程序现在将关闭”,ToastLength.Short);
toast.Show();
}
否则{
news=JsonConvert.DeserializeObject(内容);
}
}
Console.Out.WriteLine(“现在:\r\n{0}”,新闻[0]。标题);
}
var list=findviewbyd(Resource.Id.list);
list.Adapter=newhomescreenadapter(这是新闻);
list.ItemClick+=OnListItemClick;
var Listen=findviewbyd(Resource.Id.btnListen);
var Shows=findviewbyd(Resource.Id.btnShows);
听。点击+=(发送者,e)=>{
var second=新意图(此,放射性类型);
星触觉(秒);
};
显示。单击+=(发件人,e)=>{
var second=新意图(此,类型(ShowsActivity));
星触觉(秒);
};
}
受保护的void OnListItemClick(对象发送者,AdapterView.ItemClickEventArgs e)
{
var listView=发送方作为listView;
var t=新闻[e.位置];
var second=新意图(此,类型为(NewsActivity));
第二个标题(“新闻标题”,t.title);
第二,PutExtra(“新闻正文”,t.body);
第二,PutExtra(“newsImage”,t.image);
第二,PutExtra(“新闻标题”,t.caption);
星触觉(秒);
Console.WriteLine(“单击”+t.title);
}
}
我遇到的问题是,应用程序会粘在启动页面上,应用程序输出会告诉我,我在主线程上运行了太多
什么是分离下载请求以在后台工作的方法?是的,有,您需要使用,也应该有帮助。如果您使用的.Net/Mono版本支持,那么您可以简单地执行
private class myTask extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
}
@Override
protected Void doInBackground(Void... params) {
// Runs on the background thread
return null;
}
@Override
protected void onPostExecute(Void res) {
}
}
async void DisplayNews()
{
string url = "http://rapstation.com/webservice.php";
HttpClient client = new HttpClient();
string content = await client.GetStringAsync(url);
NewsObject[] news = JsonConvert.DeserializeObject<NewsObject[]>(content);
//!! Your code to add news to some control
}
async void DisplayNews()
{
字符串url=”http://rapstation.com/webservice.php";
HttpClient=新的HttpClient();
string content=wait client.GetStringAsync(url);
NewsObject[]news=JsonConvert.DeserializeObject(内容);
//!!将新闻添加到某些控件的代码
}
如果没有,那么您可以使用的
void DisplayNews2()
{
字符串url=”http://rapstation.com/webservice.php";
Task.Factory.StartNew(()=>
{
使用(var client=new WebClient())
{
字符串内容=client.DownloadString(url);
返回JsonConvert.DeserializeObject(内容);
}
})
.ContinueWith((任务,y)=>
{
NewsObject[]news=task.Result;
//!!将新闻添加到某些控件的代码
},null,TaskScheduler.FromCurrentSynchronizationContext());
}
我已经研究过asynctask,但每次我尝试以您链接的指南所示的方式实现它时,都会发现错误,缺少指令和当前上下文中不存在的内容。您能更具体一点吗?我可能可以帮助您啊,所以我对子类化不是很确定,但这似乎对asynctask相当重要。去解决这个问题吧,谢谢你的帮助!啊哈!当我试图创建这个类时,它给了我一个错误,在顶部说意外的符号“extends”。我该如何解决这个问题?我在标记中特别指出,这是在C#中,因此如果您上面提供的代码是在Java中,我不会是更明智的。为什么您要在Java android线程中发布,而不提及您需要它在C#中编译的事实?选择只使用标记?
async void DisplayNews()
{
string url = "http://rapstation.com/webservice.php";
HttpClient client = new HttpClient();
string content = await client.GetStringAsync(url);
NewsObject[] news = JsonConvert.DeserializeObject<NewsObject[]>(content);
//!! Your code to add news to some control
}
void DisplayNews2()
{
string url = "http://rapstation.com/webservice.php";
Task.Factory.StartNew(() =>
{
using (var client = new WebClient())
{
string content = client.DownloadString(url);
return JsonConvert.DeserializeObject<NewsObject[]>(content);
}
})
.ContinueWith((task,y) =>
{
NewsObject[] news = task.Result;
//!! Your code to add news to some control
},null,TaskScheduler.FromCurrentSynchronizationContext());
}