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我开发了一个 Android RSS 阅读器。我创建了一个选项卡布局，并为每种类型的新闻（比如标题、国家、国际等）创建了每个选项卡。

然后我在 tablayout 的第一页的自定义列表视图中列出了 RSS 标题及其图像。见下图。

在此处输入图像描述

现在，当用户单击新闻标题时，会打开另一个带有新闻描述的活动（页面）。

我的问题是当用户单击选项卡并加载时，如果互联网连接不可用，我想显示一个带有两个按钮的对话框，重试和退出。

当用户单击重试时，应重新加载活动。我使用了一种方法（ if(International.Title==null) ）。但我认为它不是正确的方法。我想知道是否有更好的解决方案检查网络是否可用....

这是我的代码，

 public class International extends Activity {
    static final String URL = "http://www.abcd.com/en/taxonomy/term/3/0/feed";
    static final String KEY_HEAD = "item";
    static final String KEY_DATE = "pubDate";
    ListView list;
    InternationalAdapter adapter;

    public static String[] Title;
    public static String[] Description;
    public static String[] image;
    public static String[] Date;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.headlines);

        Bundle mybundle = new Bundle();
        mybundle.putString("number", "0");
        new DoInBackground().execute();
    }
    public void do_update() 
        {
            internationalparser.parse();//this is the function to parse RSS feeds

        }


    public void populate_listview()
     {

        ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML from URL
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_HEAD);
        // looping through all song nodes <song>
        NodeList itemLst = doc.getElementsByTagName("item");


        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);

            //map.put(KEY_DATE, parser.getValue(e, KEY_DATE));

            newsList.add(map);
        }


        list=(ListView)findViewById(R.id.list);

        // Getting adapter by passing xml data ArrayList
        adapter=new InternationalAdapter(this, newsList);        
        list.setAdapter(adapter);


        // Click event for single list row
        list.setOnItemClickListener(new OnItemClickListener() {


            public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
                Intent myintent = new Intent("com.abcd.rssreaderinternationalpodcast.PODCAST");
                Bundle mybundle = new Bundle();
                mybundle.putInt("number", position);
                myintent.putExtras(mybundle);

                startActivity(myintent);

            }

        }); 

    }


     private class DoInBackground extends AsyncTask<Void, Void, Void>
     implements DialogInterface.OnCancelListener
{   
private ProgressDialog dialog;
private Intent intent;
private Intent intent2;

public void onPreExecute() 
{

    dialog = ProgressDialog.show(International.this, "", "Loading", true);

}

protected Void doInBackground(Void... unused) 
{ 


do_update(); 
return null; 
}

public void retry()
{

    internationalparser.parse();
}

protected void onPostExecute(Void unused) 
{ 


    if(International.Title!=null)
    {

        dialog.dismiss();
        populate_listview();

    }
    if(International.Title==null) ///this is what I tried.
    {
        dialog.dismiss();
         AlertDialog.Builder alertbox = new AlertDialog.Builder(International.this);

          alertbox.setMessage("Error in connection!");
          alertbox.setPositiveButton("Retry", new DialogInterface.OnClickListener() {

             public void onClick(DialogInterface arg0, int arg1) {

               retry();             //here i want to reload  activity

             }

         });

         alertbox.setNegativeButton("Exit", new DialogInterface.OnClickListener() {


             public void onClick(DialogInterface arg0, int arg1) {

                 finish();

             }

         });

         alertbox.show();

    }

}

public void onCancel(DialogInterface dialog) 
{ 
cancel(true); 
dialog.dismiss(); 
  }
 }
}
4

2 回答 2

2

这是我的重试/退出互联网连接课程

用法：

URLContent httpContent = new URLContent(this);
String test =  httpContent.getContent("http://www.hotmail.com/");

班级：

import java.io.BufferedReader;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URI;


import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class URLContent {

    MainActivity mMainActivity;
    String returnData;
    String address;

    public URLContent(MainActivity mMainActivity)  
    {
        this.mMainActivity = mMainActivity;
    }


    public String getContent(String address)
    {
        this.address = address;
        processContent(address);
        return returnData;
    }

    private void processContent(String address)
    {

        try {

            if (!isNetworkAvailable(mMainActivity))
            {
                throw new Exception("No internet connectivity.");
            }

            HttpClient client = new DefaultHttpClient();
            HttpGet request = new HttpGet();
            request.setURI(new URI(address));
            HttpResponse response = client.execute(request);

                if (response.getStatusLine().getStatusCode() == 200)
                {
                    InputStream ips  = response.getEntity().getContent();
                    BufferedReader buf = new BufferedReader(new InputStreamReader(ips,"UTF-8"));

                    StringBuilder sb = new StringBuilder();
                    String s;
                    while(true)
                    {
                        s = buf.readLine();
                        if(s==null || s.length()==0)
                            break;
                        sb.append(s);

                    }
                    buf.close();
                    ips.close();

                    returnData = sb.toString();
                }
                else
                {
                    throw new Exception();
                }

        } catch (Exception e) {

             makeAndShowDialogBox(e.getMessage()).show();
        }

    }

    private static boolean isNetworkAvailable(Context context) 
    {
       ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
       if (connectivity == null) 
       {
           return false;
       } else 
       {
          NetworkInfo[] info = connectivity.getAllNetworkInfo();
          if (info != null) 
          {
             for (int i = 0; i < info.length; i++) 
             {
                if (info[i].getState() == NetworkInfo.State.CONNECTED) 
                {
                   return true;
                }
             }
          }
       }
       return false;
    }

    private AlertDialog makeAndShowDialogBox(String msg)
    {
        AlertDialog myQuittingDialogBox =  new AlertDialog.Builder(mMainActivity) 

            .setCancelable(false)
            .setTitle(R.string.connectionerr) 
            .setMessage(msg) 

            .setPositiveButton("Retry", new DialogInterface.OnClickListener() { 
                public void onClick(DialogInterface dialog, int whichButton) { 
                 //whatever should be done when answering "YES" goes here
                    getContent(address);
                }              
            })//setPositiveButton
            .setNegativeButton("Exit", new DialogInterface.OnClickListener() { 
                public void onClick(DialogInterface dialog, int whichButton) { 
                 //whatever should be done when answering "NO" goes here
                    mMainActivity.finish();
             } 
            })//setNegativeButton

            .create();

            return myQuittingDialogBox;
    }

}
于 2012-09-21T22:52:41.757 回答
1 
public static boolean isNetworkAvailable(Context context) {
        isNetworkAvailable = false;
       ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
       if (connectivity == null) {
           return false;
       } else {
          NetworkInfo[] info = connectivity.getAllNetworkInfo();
          if (info != null) {
             for (int i = 0; i < info.length; i++) {
                if (info[i].getState() == NetworkInfo.State.CONNECTED) {
                    isNetworkAvailable = true;
                   return true;
                }
             }
          }
       }
       return false;
    }//isNetworkAvailable()

使用上述方法检查互联网连接，如果没有互联网连接，则引发 AlertDialog。

private AlertDialog makeAndShowDialogBox(){
    AlertDialog myQuittingDialogBox = 

        new AlertDialog.Builder(this) 
        //set message, title, and icon
        .setTitle("Terminator") 
        .setMessage("Are you sure that you want to quit?") 
        .setIcon(R.drawable.ic_menu_end_conversation)

        .setPositiveButton("Retry", new DialogInterface.OnClickListener() { 
            public void onClick(DialogInterface dialog, int whichButton) { 
             //whatever should be done when answering "YES" goes here
            }              
        })//setPositiveButton
        .setNegativeButton("NO", new DialogInterface.OnClickListener() { 
            public void onClick(DialogInterface dialog, int whichButton) { 
             //whatever should be done when answering "NO" goes here
         } 
        })//setNegativeButton

        .create();

        return myQuittingDialogBox;
}

更新：：

new DoInBackground().execute();

如下替换此行并尝试

if(isNetworkAvailable(YourActivity.this))
    new DoInBackground().execute();
else{
    makeAndShowDialogBox();
}
于 2012-04-28T06:37:46.467 回答