java - 从服务器读取 JSON (Java)

Question

首先，很抱歉提出这个愚蠢的问题。

任何人都可以帮我提供有关如何从服务器读取此 JSON 文件的代码吗？看了几个教程后，我搞砸了我的 Java 代码。

[
  {
    "name": "Coleen Sanford",
    "location": {
      "latitude": -60.489023,
      "longitude": -32.311668
    }
  },
  {
    "name": "Bethany Church",
    "location": {
      "latitude": -1.304805,
      "longitude": -80.670287
    }
  },
  {
    "name": "Kristy Ware",
    "location": {
      "latitude": -46.443562,
      "longitude": -46.426997
    }
  },
  {
    "name": "Avery Navarro",
    "location": {
      "latitude": 35.719469,
      "longitude": -172.783006
    }
  },
  {
    "name": "Robyn Cruz",
    "location": null
  },
  {
    "name": "Vinson Hays",
    "location": null
  }
]

这是我的代码:

/**
 * Async task class to get json by making HTTP call
 */
private class GetContacts extends AsyncTask<Void, Void, Void> {

    @Override
    protected void onPreExecute() {
        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) {
        HttpHandler sh = new HttpHandler();

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

        Log.e(TAG, "Response from url: " + jsonStr);

        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);

                // Getting JSON Array node
                JSONArray  contacts = new JSONArray (jsonStr);

                // looping through All Contacts
                for (int i = 0; i < contacts.length(); i++) {
                    JSONObject c = contacts.getJSONObject(i);

                    String name = c.getString("name");

                    // Phone node is JSON Object
                    JSONObject phone = c.getJSONObject("location");
                    String latitude = phone.getString("latitude");
                    String longitude = phone.getString("longitude");

                    // tmp hash map for single contact
                    HashMap<String, String> contact = new HashMap<>();

                    // adding each child node to HashMap key => value
                    contact.put("name", name);
                    contact.put("latitude", latitude);
                    contact.put("longitude", longitude);

                    // adding contact to contact list
                    contactList.add(contact);
                }
            } catch (final JSONException e) {
                Log.e(TAG, "Json parsing error: " + e.getMessage());
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Json parsing error: " + e.getMessage(),
                                Toast.LENGTH_LONG)
                                .show();
                    }
                });

            }
        } else {
            Log.e(TAG, "Couldn't get json from server.");
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Toast.makeText(getApplicationContext(),
                            "Couldn't get json from server. Check LogCat for possible errors!",
                            Toast.LENGTH_LONG)
                            .show();
                }
            });

        }

        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[]{"name", "latitude",
                "longitude"}, new int[]{R.id.name,
                R.id.latitude, R.id.longitude});

        lv.setAdapter(adapter);
    }

}}

Answer 1

首先你可以使用Gson这是一个用于序列化和反序列化 Json 的 google powerd 工具

然后在你的代码中添加gson依赖，

    compile 'com.google.code.gson:gson:2.7'

接下来你要做的是创建一些示例模型类来序列化你的 json 数据，使用这个 link并粘贴您的 json 数据并创建相应的类

然后是 java 代码，(假设您的基础模型类名称是 UserLocation

Userlocation

    public class UserLocation{
        private Location location;

        private String name;

        public Location getLocation ()
        {
            return location;
        }

        public void setLocation (Location location)
        {
            this.location = location;
        }

        public String getName ()
        {
            return name;
        }

        public void setName (String name)
        {
            this.name = name;
        }
  }

Location

    public class Location {
    private double longitude;

    private double latitude;

    public double getLongitude ()
    {
        return longitude;
    }

    public void setLongitude (double longitude)
    {
        this.longitude = longitude;
    }

    public double getLatitude ()
    {
        return latitude;
    }

    public void setLatitude (double latitude)
    {
        this.latitude = latitude;
    }
}

在代码中

List<UserLocation> userLocationList = Arrays.asList(new Gson().fromJson(yourResponseString, UserLocation[].class));

就是这样，所有内容都在这个 userLocationList

下

快乐的编码.. :)