如何使用 json 解析在 android 中列出来自 google api 的数据？

Question

我的代码在解析数据时返回一个null 值。

还有谁能告诉我我们检索到的数据可以显示在列表中吗？

这是我的代码

主 Activity.java

public class MainActivity extends ListActivity {
private ProgressDialog pDialog;

// URL to get contacts JSON
private static String url = "https://maps.googleapis.com/maps/api/place/details/json?reference= CnRsAAAA9ErLnmGfgp5Z67O5YXj3cDefnl7_-aVpk8Gy-bA0jJ3T1b8MZbnNTfCr93U5ylAIlU_6T-1paayMmG48-Sk0UWjMea_oC_qecuPKiL2A_cwoVs-K9EuGfOqhmOKO31g0PQdLDEScBl9cDXEU_txF2BIQjmaqLKCitDU8c1Rg-8aIGBoUSTdyLb9MCOmv0Vh9nGNxQVSgg94&sensor=false&key=AIzaSyC7x-9sdw_fYwS-e4WLoXB1QaC8OpES9pA";

// JSON Node names

// contacts JSONArray
JSONArray contacts = null;

// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    contactList = new ArrayList<HashMap<String, String>>();

    ListView lv = getListView();
    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            // TODO Auto-generated method stub

        }

    });
    // Calling async task to get json
            new GetContacts().execute();
}

private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        super.onPreExecute();
        // Showing progress dialog
        pDialog = new ProgressDialog(MainActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setCancelable(false);
        pDialog.show();
    }
    @Override
    protected Void doInBackground(Void... arg0) {
        // Creating service handler class instance
        ServiceHandler sh = new ServiceHandler();

        // Making a request to url and getting response
        String jsonStr = sh.makeServiceCall(url, ServiceHandler.POST);

        Log.d("Response: ", "> " + jsonStr);


        return null;
    }


@Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);
    // Dismiss the progress dialog
    if (pDialog.isShowing())
        pDialog.dismiss();
    /**
     * Updating parsed JSON data into ListView
     * */
/*  ListAdapter adapter = new SimpleAdapter(
            MainActivity.this, contactList,
            R.layout.list_item, new String[] { TAG_LONGNAME, TAG_SHORTNAME,
                    TAG_TYPES }, new int[] { R.id.name,
                    R.id.email, R.id.mobile });

    setListAdapter(adapter);
*/
}
}

和ServiceHandler .java

 public class ServiceHandler {

static String response = null;
public final static int GET = 1;
public final static int POST = 2;

public ServiceHandler() {

}

/*
 * Making service call
 * @url - url to make request
 * @method - http request method
 * */
public String makeServiceCall(String url, int method) {
    return this.makeServiceCall(url, method, null);
}

/*
 * Making service call
 * @url - url to make request
 * @method - http request method
 * @params - http request params
 * */
public String makeServiceCall(String url, int method,
        List<NameValuePair> params) {
    try {
        // http client
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpEntity httpEntity = null;
        HttpResponse httpResponse = null;

        // Checking http request method type
        if (method == POST) {
            HttpPost httpPost = new HttpPost(url);
            // adding post params
            if (params != null) {
                httpPost.setEntity(new UrlEncodedFormEntity(params));
            }

            httpResponse = httpClient.execute(httpPost);

        } else if (method == GET) {
            // appending params to url
            if (params != null) {
                String paramString = URLEncodedUtils
                        .format(params, "utf-8");
                url += "?" + paramString;
            }
            HttpGet httpGet = new HttpGet(url);

            httpResponse = httpClient.execute(httpGet);

        }
        httpEntity = httpResponse.getEntity();
        response = EntityUtils.toString(httpEntity);

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

    return response;
}
 }

Answer 1

尝试下面的代码来调用 url 并以字符串形式获取响应。

public static String callRequestWebservice(String p_url) {
        String m_response = null;
        HttpClient client = new DefaultHttpClient();
        HttpGet httpget = new HttpGet(p_url);
        HttpResponse response;
        System.err.println("Request URL---------->" +  p_url);
        try {
            response = client.execute(httpget);
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                InputStream in = response.getEntity().getContent();
                StringBuilder sb = new StringBuilder();
                String line = "";
                BufferedReader bf = new BufferedReader(
                        new InputStreamReader(in));
                while ((line = bf.readLine()) != null) {
                    sb.append(line);
                }
                m_response = sb.toString();
                System.err.println("JSON Response--->" + m_response);
            }
        } catch (ClientProtocolException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        return m_response;
    }

EIDTED：

如下解析响应：

try {
                    JSONObject m_obj = new JSONObject(response);
                    JSONObject result_obj = m_obj.getJSONObject("result");
                    JSONArray m_arr = result_obj
                            .getJSONArray("address_components");
                    Log.e("Formate", result_obj.getString("formatted_address"));
                    Log.e("geometry", result_obj.getString("geometry"));

                    for (int i = 0; i < m_arr.length(); i++) {
                        JSONObject m_sJobj = m_arr.getJSONObject(i);

                        Log.e("ICon", m_sJobj.getString("long_name"));
                        Log.e("Name", m_sJobj.getString("short_name")
                                + "City---" + m_sJobj.getString("types"));
                    }
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

如下修改你的代码：

private class GetContacts extends AsyncTask<Void, Void, Void> {

@Override
protected void onPreExecute() {
    // TODO Auto-generated method stub
    super.onPreExecute();
    // Showing progress dialog
    pDialog = new ProgressDialog(MainActivity.this);
    pDialog.setMessage("Please wait...");
    pDialog.setCancelable(false);
    pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {

    // Making a request to url and getting response
    String jsonStr = callRequestWebservice(url);
    Log.d("Response: ", "> " + jsonStr);
    return jsonStr;
}

@Override
protected void onPostExecute(Void result) {
    super.onPostExecute(result);
    // Dismiss the progress dialog
    if (pDialog.isShowing())
        pDialog.dismiss();
      if(result !=null)
      {
                  try {
                JSONObject m_obj = new JSONObject(result);
                JSONObject result_obj = m_obj.getJSONObject("result");
                JSONArray m_arr = result_obj
                        .getJSONArray("address_components");
                Log.e("Formate", result_obj.getString("formatted_address"));
                Log.e("geometry", result_obj.getString("geometry"));

                for (int i = 0; i < m_arr.length(); i++) {
                    JSONObject m_sJobj = m_arr.getJSONObject(i);
                       Log.e("ICon", m_sJobj.getString("long_name"));
                      Log.e("Name", m_sJobj.getString("short_name")
                        + "City---" + m_sJobj.getString("types"));
                    }
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
   }
/**
 * Updating parsed JSON data into ListView
 * */
 /*  ListAdapter adapter = new SimpleAdapter(
        MainActivity.this, contactList,
        R.layout.list_item, new String[] { TAG_LONGNAME, TAG_SHORTNAME,
                TAG_TYPES }, new int[] { R.id.name,
                R.id.email, R.id.mobile });

setListAdapter(adapter);
 */
}