安卓的AsyncTask [英] Android AsyncTask

问题描述

我是充分利用我的AsyncTask？有人可以纠正我的codeS，如果它是错误的。我只是想确保我的AsyncTask全面工作，所以我不会在未来获得任何麻烦。我想使用的AsyncTask我所有的课程。它是一个好的做法呢？

 公共类SingleMenuItemActivity延伸活动{

    // XML节点键
静态最后弦乐KEY_TITLE =称号;
静态最后弦乐KEY_ARTIST =艺术家;
静态最后弦乐KEY_THUMB_URL =thumb_url;
私人ProgressDialog pDialog;
字符串称号;
字符串的艺术家;
字符串IMAGE_URL;
ImageView的观点;

    @覆盖
    公共无效的onCreate（包savedInstanceState）{
        super.onCreate（savedInstanceState）;
        的setContentView（R.layout.single_list_item）;
        新loadSingleView（）执行（）。


        鉴于=（ImageView的）findViewById（R.id.single_image）;



    }



公共类loadSingleView扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; {

        @覆盖
        在preExecute保护无效（）{
            super.on preExecute（）;
            pDialog =新ProgressDialog（
                    SingleMenuItemActivity.this）;
            pDialog.setMessage（连接到服务器...）;
            pDialog.setIndeterminate（假）;
            pDialog.setCancelable（假）;
            pDialog.show（）;
        }
        @覆盖
        保护字符串doInBackground（字符串参数... args）{
            //从后台线程更新UI


            意图= getIntent（）;

            IMAGE_URL = in.getStringExtra（KEY_THUMB_URL）;
                        标题= in.getStringExtra（KEY_TITLE）;
            艺术家= in.getStringExtra（KEY_ARTIST）;






            返回null;

                    }
        @覆盖
        保护无效onPostExecute（字符串参数）{
            让所有的产品之后//关闭该对话框

            ImageLoader的imgLoader =新ImageLoader的（getApplicationContext（））;

            imgLoader.DisplayImage（图片网址，查看）;

            TextView的lblName =（TextView中）findViewById（R.id.name_title）;
            TextView的lblCost =（TextView中）findViewById（R.id.name_artist）;

            lblName.setText（职称）;
            lblCost.setText（艺术家）;
            pDialog.dismiss（）;

        }


}
 

解决方案

您需要更新的方法，在UI onPostExecute（）。我喜欢将我的任务分解成他们自己的文件。这样，我们的关注点分离，这使得它更容易理解的code。我们可以用一个接口来定义一个回调方法做到这一点

 公共类LoadSingleView扩展的AsyncTask＆LT;字符串，字符串，字符串＆GT; {

    公共接口LoadSingleViewHandler {
        无效onSingleViewLoad（字符串结果）;
    }

    私人LoadSingleViewHandler处理程序;

    公共LoadSingleView（LoadSingleViewHandler处理）{
        this.handler =处理程序;
    }

    @覆盖
    保护字符串doInBackground（字符串参数... args）{
        //做手术这里并返回结果
        //操作通常是一些网络请求
        //或者一些需要大量的时间
    }

    @覆盖
    保护无效onPostExecute（字符串结果）{
        handler.onSingleViewLoad（结果）;
    }
}
 

现在刚刚开始从活动的任务，并将活动的实施 LoadSingleViewHandler 接口。

Am i fully utilising my AsyncTask? Can someone correct my codes if it is wrong. I just want to make sure my AsyncTask fully works so i wont get any trouble in the future. I wish to use AsyncTask for all my classes. Is it a good practice?

    public class SingleMenuItemActivity  extends Activity {

    // XML node keys
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";  
static final String KEY_THUMB_URL = "thumb_url";
private ProgressDialog pDialog;
String title;
String artist;
String image_url;
ImageView view;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.single_list_item);
        new loadSingleView().execute(); 


        view = (ImageView) findViewById(R.id.single_image);



    }



public class loadSingleView extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(
                    SingleMenuItemActivity.this);
            pDialog.setMessage("Connecting to Server ...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }
        @Override
        protected String doInBackground(String... args) {
            // updating UI from Background Thread


            Intent in = getIntent();

            image_url = in.getStringExtra(KEY_THUMB_URL);
                        title = in.getStringExtra(KEY_TITLE);
            artist = in.getStringExtra(KEY_ARTIST);






            return null;

                    }
        @Override       
        protected void onPostExecute(String args) {
            // dismiss the dialog after getting all products

            ImageLoader imgLoader = new ImageLoader(getApplicationContext());

            imgLoader.DisplayImage(image_url, view);

            TextView lblName = (TextView) findViewById(R.id.name_title);
            TextView lblCost = (TextView) findViewById(R.id.name_artist);

            lblName.setText(title);
            lblCost.setText(artist);
            pDialog.dismiss();

        }


}

解决方案

You have to update the UI from the method onPostExecute(). I like to move my task into their own files. This way we have a separation of concerns which makes it more easier to understand the code. We can do this by using a interface to define a callback method

public class LoadSingleView extends AsyncTask<String, String, String> {

    public interface LoadSingleViewHandler {
        void onSingleViewLoad(String result);
    }

    private LoadSingleViewHandler handler;

    public LoadSingleView(LoadSingleViewHandler handler) {
        this.handler = handler;
    }

    @Override
    protected String doInBackground(String... args) {
        // Do operation here and return the result
        // Operation is usually some network request
        // or something that will take alot of time
    }

    @Override       
    protected void onPostExecute(String result) {
        handler.onSingleViewLoad(result);
    }
}

Now just start the task from the activity and have the activity implement LoadSingleViewHandler interface.

这篇关于安卓的AsyncTask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！