如何从网页（Android）获取信息？

Question

我使Android应用程序必须从页面http://example.com/get.php?id=1接收数据。为此，我用下面的方法：

private String getData() 
    { 
     HttpClient httpClient = new DefaultHttpClient(); 
     HttpContext localContext = new BasicHttpContext(); // !!! application stops here 
     HttpGet httpGet = new HttpGet("http://example.com/get.php?id=1"); 
     HttpResponse response = null; 
      try { 
       response = httpClient.execute(httpGet, localContext); 
      } catch (ClientProtocolException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     String result = ""; 

     BufferedReader reader = null; 
      try { 
       reader = new BufferedReader(
        new InputStreamReader(
         response.getEntity().getContent() 
        ) 
       ); 
      } catch (IllegalStateException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

     String line = null; 
     try { 
       while ((line = reader.readLine()) != null){ 
        result += line + "\n"; 
       } 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

     // Now you have the whole HTML loaded on the result variable 
     return result; 
    } 

我还添加了权限的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.android.repetitor_ent_free" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-permission android:name="android.permission.INTERNET" /> 

的问题是，当我在设备上运行该应用程序我得到的错误： 的意外停止应用MyApp（进程com.android.myapp）。请再试一次。

Answer 1

你有android.os.NetworkOnMainThreadException，如果你想更好的解决办法尝试使用AsyncTask。有关线索的更多信息，请参阅'processes and threads'（请仔细阅读本指南以避免将来出现此问题）。

例如，你可以尝试以下解决方法之一：

1）使用罗马的答案，并添加如下内容：

final StringBuilder sb = ... ; 
final TextView tv = ... ; 

tv.post(new Runnable() { 
     public void run() { 
      tv.setText(sb.toString()); 
     } 
    }); 

或使用活动方法：

runOnUiThread(new Runnable() { 
    public void run() { 
     final StringBuilder sb = ... ; 
     final TextView tv = ... ; 

     tv.setText(sb.toString()); 
    } 
}); 

2 ）使用AsyncTask：

new AsyncTask<Void, Void, Void>() { 
    protected Void doInBackground(Void... none) { 
     // 
     // your code 
     // 

     return null; 
    } 
    protected void onProgressUpdate(Void... none) {} 
    protected void onPostExecute(Void none) { 
     // use this to set the text 

     final StringBuilder sb = ... ; 
     final TextView tv = ... ; 

     tv.setText(sb.toString());    
    } 
}.execute(); 

Answer 2

尝试使用此：

new Thread(){ 
    @Owerride 
    public void run(){ 
     URL url = new URL(urlString); 
     URLConnection conn = url.openConnection(); 
     InputStreamReader streamReader = new InputStreamReader(conn.getInputStream()); 
     BufferedReader br = new BufferedReader(streamReader); 
     StringBuilder sb = new StringBuilder(); 
     String line = null; 
     while((line = br.readLine()) != null) { 
      sb.append(line);sb.append("\n"); 
     } 
    } 
}.start(); 

Answer 3

你可以试试下面的代码：

HttpURLConnection conn = null; 

try { 

    URL url = new URL("http://example.com/get.php?id=1"); 
    conn = (HttpURLConnection) url.openConnection(); 

    conn.setRequestMethod("GET"); 
    conn.setRequestProperty("Content-length", "0"); 
    conn.setUseCaches(false); 
    conn.setAllowUserInteraction(false); 
    conn.connect(); 

    InputStreamReader streamReader = new InputStreamReader(conn.getInputStream()); 

    //Do what you need with the data here 

    } catch (Exception e) { 
     // Handle your exceptions 
    } finally { 
     if (conn != null) { 
      conn.disconnect(); 
      conn = null; 
     } 
    } 
}