如何通过 asyncTask 方法解析来自 2 个不同 URL 的数据

Question

我有一个从 JSON URL 获取数据的应用。它与一个 URL 完美配合，但我需要同时从两个 JSON URL 获取数据。就像来自一个 URL 的一些数据和来自另一个 URL 的一些数据。并在两个 textView 中显示它们。

这是我的应用，它目前不加载任何数据。

MainActivity：

public class MainActivity extends Activity {

//URL to get JSON Array
private static String url1 = "http://api.worldbank.org/countries/de?format=json";
private static String url2 = "http://api.worldbank.org/countries/it?format=json";

//JSON Node Names 
private static final String CountryNAME1 = "name";
private static final String CountryNAME2 = "name";
JSONArray user = null;

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

    new GetJSONTask().execute(url1);
    //new GETJSONTask().execute(url2);
}
class GetJSONTask extends AsyncTask<String, Void, JSONObject> {


    protected JSONObject doInBackground(String... urls) {
        // Creating new JSON Parser
        JSONParser jParser = new JSONParser();

        // Getting JSON from URL
        JSONObject json1 = jParser.getJSONFromUrl(url1);
        JSONObject json2 = jParser.getJSONFromUrl(url2);

        return json1;
    }
    protected void onPostExecute(JSONObject json1, JSONObject json2) {
        //Getting JSON Array
        try {

            //For Country 1
            // Get the array
            JSONArray countryArC1 = json1.getJSONArray("myValues");
            JSONObject countryObC1 = countryArC1.getJSONObject(0);

            JSONArray countryAr2C1 = countryArC1.getJSONArray(1);
            JSONObject countryOb2C1 = countryAr2C1.getJSONObject(0);

            //For Country 2
         // Get the array
            JSONArray countryArC2 = json2.getJSONArray("myValues");
            JSONObject countryObC2 = countryArC2.getJSONObject(0);

            JSONArray countryAr2C2 = countryArC2.getJSONArray(1);
            JSONObject countryOb2C2 = countryAr2C2.getJSONObject(0);




            //Storing JSON item in a Variable
            String name1 = countryOb2C1.getString(CountryNAME1);
            String name2 = countryOb2C2.getString(CountryNAME2);

            //Importing TextView
            final TextView textView1 = (TextView)findViewById(R.id.url1);
            final TextView textView2 = (TextView)findViewById(R.id.url2);

            //Set JSON Data in TextView
            textView1.setText(name1);
            textView2.setText(name2);

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

JSONParser：

public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

// constructor
public JSONParser() {

}

public JSONObject getJSONFromUrl(String url) {

    //System.out.println("url getJSONfromUrl " + url);
    //url = "http://api.worldbank.org/countries/CA/indicators/SP.POP.TOTL?date=1980:1981&format=json";

    // Making HTTP request
    try {
        // defaultHttpClient
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet httpGet = new HttpGet(url);

        HttpResponse httpResponse = httpClient.execute(httpGet);
        HttpEntity httpEntity = httpResponse.getEntity();
        is = httpEntity.getContent();           

    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(
                is, "iso-8859-1"), 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
        is.close();
        json = sb.toString();
        System.out.println("JSONParser string: " + json);
    } catch (Exception e) {
        Log.e("Buffer Error", "Error converting result " + e.toString());
    }

    // try parse the string to a JSON object
    try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }


    if (json.startsWith("[")) {
        // We have a JSONArray
        try {
            jObj = new JSONObject();
            jObj.put("data", new JSONArray(json));
        } catch (JSONException e) {
            Log.d("JSON Parser", "Error parsing JSONArray " + e.toString());
        }
        return jObj;
    }

 // try parse the string to a JSON object
    /*try {
        jObj = new JSONObject(json);
    } catch (JSONException e) {
        Log.e("JSON Parser", "Error parsing data " + e.toString());
    }*/

    // return JSON String
    return jObj;



}
}

XML：

 <TextView
        android:id="@+id/url1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
         />

    <TextView
        android:id="@+id/url2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/url1"
        android:layout_marginTop="104dp"
         />

我认为主要问题是 new GetJSONTask().execute(url1); 和 JSONObject json1 = jParser.getJSONFromUrl(url1); 因为我不能有 2 个 GetJSONTASK，也不能同时返回 json1 和 json2。

有什么想法吗？

Answer 1

我建议你改变你的方法

class GetJSONTask extends AsyncTask<String, Void, JSONObject[]> {

 ...

 protected JSONObject[] doInBackground(String... urls) {
    // Creating new JSON Parser
    JSONParser jParser = new JSONParser();

    // Getting JSON from URL
    JSONObject[] jsons = new JSONObject[2];
    jsons[0] = jParser.getJSONFromUrl(url1);
    jsons[1] = jParser.getJSONFromUrl(url2);

    return jsons;
}
protected void onPostExecute(JSONObject[] jsons) {
    JSONObject json1 = jsons[0];
    JSONObject json2 = jsons[1];
    // do you work after this
}
}

希望对您有所帮助！

Answer 2

变体 A) 您可以像这样执行 GetJSONTask：

new GetJSONTask().execute(url1, url2);

并像这样访问 AsyncTask 中的 URL：

 class GetJSONTask extends AsyncTask<String, Void, JSONObject[]> {
     ...
     JSONObject[] doInBackground(String... urls) {

         // Getting JSON from URL
        JSONObject json1 = jParser.getJSONFromUrl(urls[1]);
        JSONObject json2 = jParser.getJSONFromUrl(url2[2]);

        return new JSONObject[] {json1, json2};
    }

    void onPostExecute(JSONObject[] jsons) { ... }

}

变体 B) 如果您想让进程真正并行运行，您可以添加另一个 AsyncTask，它创建 2 个子任务并等待它们的结果。在大多数设备上，这将是执行该任务所需时间的一半。

class GetTwoJsonsTask extends AsyncTask<String, Void, JSONObject[]> {
    JSONObject[] doInBackground(urls) {

        task1 = new GetJSONTask().execute(urls[1]);
        task2 = new GetJSONTask().execute(urls[2]);

        // block until sub-tasks are finished
        JSONObject json1 = task1.get();
        JSONObject json2 = task2.get();

        return new JSONObject[] {json1, json2};
    }

    void onPostExecute(JSONObject[] jsons) { ... }

}

Answer 3

我就是这样做的，方法很简单

public class GetSetting extends AsyncTask<List<String>,Void,List<String>> {

    String urls[] =  new String[]{"http:// first url",
                              "http:// second url"};


    @Override
    protected ArrayList<String> doInBackground(List<String>... lists) {

        HttpURLConnection urlConnection;
        InputStream inputStream;
        BufferedReader bufferedReader;
        URL urlIfSup;
        ArrayList<String> result = new ArrayList<>();
        try {

            // here to connect and get a different type of data  

            for (int i = 0; i < 2; i++){ // this one for connect the url from url array in every loop 

                urlIfSup = new URL(urls[i]);
                urlConnection = (HttpURLConnection) urlIfSup.openConnection();
                inputStream = urlConnection.getInputStream();
                bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"utf-8"));

                String data = bufferedReader.readLine();

                while(bufferedReader.readLine() != null){

                    data += bufferedReader.readLine();
                }
                if (i==0) {

                    // do something for the first url

                }else if (i==1){

                  // do something for the second url
                   // use jSON if you want 


                  // then do this at the last url       
                    urlConnection.disconnect();
                    inputStream.close();
                    bufferedReader.close();
                }
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


        return result;
    }
}