Android的异步后块UI线程 [英] Android asynchronous post blocks UI thread

问题描述

我开发一个Android应用程序。我要发布使用AsyncTask的一个服务器。不过，我仍然有这表明该UI线程被阻塞错误。

我要解析XML响应，并在列表视图中显示，但我无法继续，因为UI线程仍然受阻。

 公共类AsynchronousPost扩展ListActivity实现OnClickListener {的EditText SearchValue;
按钮SearchBtn;
字符串URL =;@覆盖
公共无效的onCreate（捆绑savedInstanceState）{
    super.onCreate（savedInstanceState）;
    的setContentView（R.layout.search_interface）;
    SearchBtn =（按钮）findViewById（R.id.searchbtn）;
    SearchBtn.setOnClickListener（本）;
}公共无效的onClick（视图查看）{ 新MyAsyncTask（）执行（）;
}私有类MyAsyncTask扩展的AsyncTask＆LT;字符串，整数，文档＆GT; {    私人最终字符串URL =URL;    私人最终字符串username =用户名;
    私人最终字符串密码=密码;
    私人的EditText SearchValue;
    @覆盖
    受保护的文档doInBackground（字符串...为arg0）{
        // TODO自动生成方法存根        getXmlFromUrl（URL）; //获取XML
        返回null;
    }            @覆盖
    保护无效onPostExecute（）{            //要解析XML响应
             //显示列表视图
            }
    公共字符串getXmlFromUrl（字符串URL）{
        字符串XML = NULL;        尝试{
            // defaultHttpClient
            DefaultHttpClient的HttpClient =新DefaultHttpClient（）;
            HttpPost httpPost =新HttpPost（URL）;
            SearchValue =（EditText上）findViewById（R.id.search_item）;
            字符串Schvalue = SearchValue.getText（）的toString（）。            //添加数据
            清单＆LT;＆的NameValuePair GT; namevaluepairs中=新的ArrayList＆LT;＆的NameValuePair GT;（
                    5）;
            namevaluepairs中
                    。新增（新BasicNameValuePair（用户名的用户名））;
            namevaluepairs中
                    。新增（新BasicNameValuePair（密码，密码））;
            nameValuePairs.add（新BasicNameValuePair（searchItem
                    Schvalue））;            //响应存储在响应VAR
            HTT presponse HTT presponse = httpClient.execute（httpPost）;
            HttpEntity httpEntity = HTT presponse.getEntity（）;
            XML = EntityUtils.toString（httpEntity）;        }赶上（UnsupportedEncodingException五）{
            e.printStackTrace（）;
            返回null;
        }赶上（ClientProtocolException E）{
            e.printStackTrace（）;
            返回null;
        }赶上（IOException异常五）{
            e.printStackTrace（）;
            返回null;
        }
        //返回XML
        返回XML;
    }
}}
 

解决方案

 受保护对象doInBackground（字符串... PARAMS）{
    // AsyncTask的这种方法是不是在UI线程中运行 - 在这里只做非UI TAKS
    返回结果;
}@覆盖
保护无效onPostExecute（对象结果）{
   //我不知道，但我认为这种方法是在UI线程运行
   //如果你有很长的操作这里你会阻塞UI线程
   //放在doInBackground的任务...
   //填写UI元素使用元素
   //
   runOnUiThread（新的Runnable（）{
      @覆盖
      公共无效的run（）{
        //在这里填写您的UI元素  }}）;
}
 

I'm developing an Android app. I want to post to a server using asynctask. However, I still have an error which indicates that the UI thread is blocked.

I want to parse the XML response and display it in a list view, but I cannot proceed because the UI thread is still blocked.

public class AsynchronousPost extends ListActivity implements OnClickListener {

EditText SearchValue;
Button SearchBtn;
String URL = "";



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.search_interface);


    SearchBtn = (Button) findViewById(R.id.searchbtn);


    SearchBtn.setOnClickListener(this);
}

public void onClick(View views) {

 new MyAsyncTask().execute();


}

private class MyAsyncTask extends AsyncTask<String, Integer, Document> {

    private final String URL = "url";

    private final String username = "username";
    private final String password = "password";
    private EditText SearchValue;


    @Override
    protected Document doInBackground(String... arg0) {
        // TODO Auto-generated method stub

        getXmlFromUrl(URL); // getting XML
        return null;


    }

            @Override
    protected void onPostExecute() {

            //want to parse xml response
             //display on listview
            }


    public String getXmlFromUrl(String url) {
        String xml = null;

        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);
            SearchValue = (EditText) findViewById(R.id.search_item);
            String Schvalue = SearchValue.getText().toString();

            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(
                    5);
            nameValuePairs
                    .add(new BasicNameValuePair("username", username));
            nameValuePairs
                    .add(new BasicNameValuePair("password", password));
            nameValuePairs.add(new BasicNameValuePair("searchItem",
                    Schvalue));

            // response stored in response var
            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            xml = EntityUtils.toString(httpEntity);

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return null;
        } catch (ClientProtocolException e) {
            e.printStackTrace();
            return null;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        // return XML
        return xml;
    }




}

}

解决方案

protected Object doInBackground(String... params) {
    //this method of AsyncTask is not running on the UI Thread -- here do just non UI         taks
    return result;   
}

@Override
protected void onPostExecute(Object result) {
   //I'm not sure but I think this method is running on the UI Thread
   //If you have long operations here to do you will block UI Thread
   //put the tasks in the doInBackground...
   //to fill the elements in the UI elements use
   // 
   runOnUiThread (new Runnable() {
      @Override
      public void run() {
        //here fill your UI elements 

  }});
}

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