使用volly进行网络连接和解析JSON

Question

我使用VollyLibrary解析JSON并将数据记录到Logconsole

我正在使用URL :：http://www.androidbegin.com/tutorial/jsonparsetutorial.txt

JSON-Response::

{ 
"worldpopulation": 
    [
         {
         "rank":1,"country":"China",
         "population":"1,354,040,000",
         "flag":"http://www.androidbegin.com/tutorial/flag/china.png"
         }, 

         {
         "rank":2,"country":"India",
         "population":"1,210,193,422",
         "flag":"http://www.androidbegin.com/tutorial/flag/india.png"
         }, 

         {
         "rank":3,"country":"United States",
         "population":"315,761,000",
         "flag":"http://www.androidbegin.com/tutorial/flag/unitedstates.png"
         }, 

         {
         "rank":4,"country":"Indonesia",
         "population":"237,641,326",
         "flag":"http://www.androidbegin.com/tutorial/flag/indonesia.png"
         }, 

         {
         "rank":5,"country":"Brazil",
         "population":"193,946,886",
         "flag":"http://www.androidbegin.com/tutorial/flag/brazil.png"
         }, 

         {
         "rank":6,"country":"Pakistan",
         "population":"182,912,000",
         "flag":"http://www.androidbegin.com/tutorial/flag/pakistan.png"
         }, 

         {
         "rank":7,"country":"Nigeria",
         "population":"170,901,000",
         "flag":"http://www.androidbegin.com/tutorial/flag/nigeria.png"
         }, 

         {
         "rank":8,"country":"Bangladesh",
         "population":"152,518,015",
         "flag":"http://www.androidbegin.com/tutorial/flag/bangladesh.png"
         }, 

         {
         "rank":9,"country":"Russia",
         "population":"143,369,806",
         "flag":"http://www.androidbegin.com/tutorial/flag/russia.png"
         }, 

         {
         "rank":10,"country":"Japan",
         "population":"127,360,000",
         "flag":"http://www.androidbegin.com/tutorial/flag/japan.png"
         } 
    ] 
}

问题我所面临的：：

1. 我能够获得JSON响应，但是我无法记录我在代码中发布的日志语句的数据

用于以下日志的ex :：

 - Log.d(" - - value - - ", value.toString());
 - Log.d(" - - items - - ", items.toString());
 - Log.d(" - - item - - ", item.toString());
 - Log.d(" - - value.optString(rank) - - ",
       value.optString("rank").toString());

MainActivity.java

public class MainActivity extends Activity {

    //Declaring the variables
    private String TAG = this.getClass().getSimpleName();
    private ListView lstView;
    private RequestQueue mRequestQueue;
    private ArrayList<ModelClass> arrNews;
    private LayoutInflater li;
    private VollyAdapter va;
    private ProgressDialog pd;
    String url = "http://www.androidbegin.com/tutorial/jsonparsetutorial.txt";

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

        li=LayoutInflater.from(this);
        arrNews=new ArrayList<ModelClass>();
        va=new VollyAdapter();
        lstView=(ListView) findViewById(R.id.listView);

        lstView.setAdapter(va);

        mRequestQueue =  Volley.newRequestQueue(this);
        pd = ProgressDialog.show(this,"Please Wait...","Please Wait...");
        try{
            Thread.sleep(2000);
        }catch(Exception e){

        }

        JsonObjectRequest jr = new JsonObjectRequest(Request.Method.GET,url,null,new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                Log.i(TAG,response.toString());
                parseJSON(response);
                va.notifyDataSetChanged();
                pd.dismiss();
                ;            }
        },new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.i(TAG,error.getMessage());
            }
        });
        mRequestQueue.add(jr);


    }

    private void parseJSON(JSONObject response) {
        try{
            JSONObject value = response.getJSONObject("response");
            Log.d(" - - value - - ", value.toString());
            JSONArray items = value.getJSONArray("worldpopulation");
            Log.d(" - - items - - ", items.toString());
            for(int i=0;i<items.length();i++){

                JSONObject item = items.getJSONObject(i);
                Log.d(" - - item - - ", item.toString());
                ModelClass nm = new ModelClass();
                nm.setRank(value.optString("rank"));
                Log.d(" - - value.optString(rank) - - ", value.optString("rank").toString());
                nm.setCountry(value.optString("country"));
                nm.setPopulation(value.optString("population"));
                arrNews.add(nm);
            }
        }
        catch(Exception e){
            e.printStackTrace();
        }



    }

    class VollyAdapter extends BaseAdapter{

        @Override
        public int getCount() {
            return arrNews.size();
        }

        @Override
        public Object getItem(int position) {
            // TODO Auto-generated method stub
            return arrNews.get(position);
        }

        @Override
        public long getItemId(int position) {
            // TODO Auto-generated method stub
            return 0;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder vh;
            if(convertView==null){
                vh=new ViewHolder();
                convertView=li.inflate(R.layout.row_listview, null);
                vh.rank=(TextView) convertView.findViewById(R.id.txtRank);
                vh.country=(TextView) convertView.findViewById(R.id.txtCountry);
                vh.population=(TextView) convertView.findViewById(R.id.txtPopulation);
                convertView.setTag(vh);
            }else{
                vh=(ViewHolder) convertView.getTag();
            }

            ModelClass mc=arrNews.get(position);
            vh.rank.setText(mc.getRank());
            vh.country.setText(mc.getCountry());
            vh.population.setText(mc.getPopulation());

            return convertView;
        }

        class ViewHolder{
            TextView rank;
            TextView country;
            TextView population;
        }

    }

}

Logcat输出：：

04-13 11:57:24.825: I/ActivityManager(79): Displayed com.example.vollytestdev/.MainActivity: +5s99ms
04-13 11:57:25.996: I/qtaguid(1251): Tagging socket 42 with tag 3ecd14a400000000(1053627556) for uid -1 failed errno=-2
04-13 11:57:25.996: I/NetworkManagementSocketTagger(1251): tagSocketFd(42, 1053627556, -1) failed with errno-2
04-13 11:57:27.915: D/Volley(1251): [109] BasicNetwork.logSlowRequests: HTTP response for request=<[ ] http://www.androidbegin.com/tutorial/jsonparsetutorial.txt 0x3ecd14a4 NORMAL 1> [lifetime=3108], [size=1497], [rc=200], [retryCount=0]
04-13 11:57:28.755: I/MainActivity(1251): {"worldpopulation":[{"rank":1,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/china.png","population":"1,354,040,000","country":"China"},{"rank":2,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/india.png","population":"1,210,193,422","country":"India"},{"rank":3,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/unitedstates.png","population":"315,761,000","country":"United States"},{"rank":4,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/indonesia.png","population":"237,641,326","country":"Indonesia"},{"rank":5,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/brazil.png","population":"193,946,886","country":"Brazil"},{"rank":6,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/pakistan.png","population":"182,912,000","country":"Pakistan"},{"rank":7,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/nigeria.png","population":"170,901,000","country":"Nigeria"},{"rank":8,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/bangladesh.png","population":"152,518,015","country":"Bangladesh"},{"rank":9,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/russia.png","population":"143,369,806","country":"Russia"},{"rank":10,"flag":"http:\/\/www.androidbegin.com\/tutorial\/flag\/japan.png","population":"127,360,000","country":"Japan"}]}
04-13 11:57:28.765: W/System.err(1251): org.json.JSONException: No value for response
04-13 11:57:28.775: W/System.err(1251):     at org.json.JSONObject.get(JSONObject.java:354)
04-13 11:57:28.775: W/System.err(1251):     at org.json.JSONObject.getJSONObject(JSONObject.java:569)
04-13 11:57:28.775: W/System.err(1251):     at com.example.vollytestdev.MainActivity.parseJSON(MainActivity.java:79)
04-13 11:57:28.775: W/System.err(1251):     at com.example.vollytestdev.MainActivity.access$3(MainActivity.java:77)
04-13 11:57:28.786: W/System.err(1251):     at com.example.vollytestdev.MainActivity$1.onResponse(MainActivity.java:62)
04-13 11:57:28.786: W/System.err(1251):     at com.example.vollytestdev.MainActivity$1.onResponse(MainActivity.java:1)
04-13 11:57:28.786: W/System.err(1251):     at com.android.volley.toolbox.JsonRequest.deliverResponse(JsonRequest.java:65)
04-13 11:57:28.786: W/System.err(1251):     at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
04-13 11:57:28.795: W/System.err(1251):     at android.os.Handler.handleCallback(Handler.java:605)
04-13 11:57:28.795: W/System.err(1251):     at android.os.Handler.dispatchMessage(Handler.java:92)
04-13 11:57:28.805: W/System.err(1251):     at android.os.Looper.loop(Looper.java:137)
04-13 11:57:28.815: W/System.err(1251):     at android.app.ActivityThread.main(ActivityThread.java:4340)
04-13 11:57:28.825: W/System.err(1251):     at java.lang.reflect.Method.invokeNative(Native Method)
04-13 11:57:28.825: W/System.err(1251):     at java.lang.reflect.Method.invoke(Method.java:511)
04-13 11:57:28.825: W/System.err(1251):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-13 11:57:28.835: W/System.err(1251):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-13 11:57:28.845: W/System.err(1251):     at dalvik.system.NativeStart.main(Native Method)
04-13 11:57:28.865: D/Volley(1251): [1] Request.finish: 4658 ms: [ ] http://www.androidbegin.com/tutorial/jsonparsetutorial.txt 0x3ecd14a4 NORMAL 1
04-13 11:59:45.394: D/dalvikvm(296): GC_CONCURRENT freed 383K, 6% free 10316K/10951K, paused 13ms+8ms
04-13 12:03:02.685: W/ThrottleService(79): unable to find stats for iface rmnet0

Answer 1

试试这个..。

像parseJSON(response.toString());那样的呼叫

private void parseJSON(String response) {
   try{
       JSONObject value = new JSONObject(response);
       Log.d(" - - value - - ", value.toString());
       JSONArray items = value.getJSONArray("worldpopulation");
       Log.d(" - - items - - ", items.toString());
       for(int i=0;i<items.length();i++){

            JSONObject item = items.getJSONObject(i);
            Log.d(" - - item - - ", item.toString());
            ModelClass nm = new ModelClass();
            nm.setRank(item.optString("rank"));
            Log.d(" - - item.optString(rank) - - ", item.optString("rank").toString());
            nm.setCountry(item.optString("country"));
            nm.setPopulation(item.optString("population"));
            arrNews.add(nm);
        }
       }
       catch(Exception e){
           e.printStackTrace();
       }
}