android - 在android中使用HttpUrlConnection查询字符串返回Null

Question

Android在解析JSON时，只解析了JSON数组的10项。在调试时，我发现 connection.openConnection() 之后的查询字符串； 返回空查询字符串，例如 http://www.example.com/recent_summary/?count=20如果我将计数减少到 5 并不重要，它仍然会返回 10 个项目。但是，当我浏览 browner 中的 URL 时。它返回所有 20 个项目..我认为我的代码有问题..服务器端工作正常还有一件事，当我在 android Studio 中检查 openConnection() 声明(URL.java)时，我发现很多红线..新手不知道它是否有帮助，但请帮助我。

public class MainListActivity extends ActionBarActivity {

protected  String TAG =  MainListActivity.class.getSimpleName(); 

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_list);

    if(isNetworkAvailable()) {
        GetPostsTask getPostsTask = new GetPostsTask();
        getPostsTask.execute();

  }else
  {
      Toast.makeText(this,"No Network", Toast.LENGTH_SHORT).show();
  }

 }

private boolean isNetworkAvailable(){
ConnectivityManager manager =(ConnectivityManager)             getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo networkInfo = manager.getActiveNetworkInfo();
    boolean isAvailable = false ;
    if (networkInfo != null && networkInfo.isConnected()){
    isAvailable = true ;
    }
   return isAvailable;
}


private class GetPostsTask extends AsyncTask<Object, Void, String>{


protected  String doInBackground(Object...arg){
        JSONObject jsonResponse ;
    try{
        URL url = new URL(http://www.example.com/recent_summary/?count=20 );
        HttpURLConnection connection = (HttpURLConnection)url.openConnection();
        connection.connect();

        int responseCode = connection.getResponseCode();
        Log.i("Response Code", ""+responseCode);

        InputStream inputStream = connection.getInputStream();
        Reader reader = new InputStreamReader(inputStream);
        BufferedReader r = new BufferedReader(reader);
        StringBuffer buffer = new StringBuffer();
        String line ;
        while((line=r.readLine()) != null){
            buffer.append(line + "\n");

        }

       Log.i("ResponseData" , ""+buffer);

        jsonResponse = new JSONObject(buffer.toString());
        JSONArray jsonPosts = jsonResponse.getJSONArray("posts") ;

        for(int i =0 ; i<jsonPosts.length() ; i++){
            JSONObject jsonPost = jsonPosts.getJSONObject(i);
            String title = jsonPost.getString("title");
            Log.i("Post"+i, title);

        }



    }catch (MalformedURLException ex){
        Log.i(TAG , "Error Found ", ex);
    }catch(IOException ex){
        Log.i(TAG , "Error Found ", ex);
    }catch (Exception ex){
        Log.i(TAG , "Error Found ", ex);
    }

    return null ;
}



  }
}

Answer 1

您的 url 似乎没有将所需的项目数正确地传送到服务器。如果您没有提供项目计数，10 应该是服务器配置为返回的默认项目计数。再次检查您的网址以查看其格式是否正确。

您提供的网址

http://www.example.com/recent_summary/?count=20

在“?”之前有一个“/”特点。可能是导致问题的原因。所以尝试像这样没有'/'字符的url

http://www.example.com/recent_summary?count=20