解析 Json 字符串以检索所有字段

Question

我一直在尝试用 volley 解析 json，不知何故我设法提取了一些数据，但我无法解析其他字段。 我正在尝试做的是检查哪个用户角色是医生并将该用户仅存储到 a1 数组列表

{"user1":{"password":"******","presence":{"lastSeen":1484695229773,"status":"online"},"role":"Patient"},"user2":{"password":"******","presence":{"lastSeen":1484695229773,"status":"offline"},"role":"Doctor"}}

这是我的代码：

   public class Users extends AppCompatActivity {
    ListView usersList;
    TextView noUsersText;
    ArrayList<String> al = new ArrayList<>();
    int totalUsers = 0;
    ProgressDialog pd;
    private Firebase mRef;

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

        usersList = (ListView)findViewById(R.id.usersList);
        noUsersText = (TextView)findViewById(R.id.noUsersText);


        pd = new ProgressDialog(Users.this);
        pd.setMessage("Loading...");
        pd.show();

        String url = "https://**********.firebaseio.com/users.json";

        StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String>(){
            @Override
            public void onResponse(String s) {
                doOnSuccess(s);
            }
        },new Response.ErrorListener(){
            @Override
            public void onErrorResponse(VolleyError volleyError) {
                System.out.println("" + volleyError);
            }
        });

        RequestQueue rQueue = Volley.newRequestQueue(Users.this);
        rQueue.add(request);

        usersList.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                UserDetails.chatWith = al.get(position);
                startActivity(new Intent(Users.this, Chat.class));
            }
        });






    }//oncreate ends here




    public void doOnSuccess(String s){
        try {
            JSONObject obj = new JSONObject(s);

            Iterator i = obj.keys();
            String key = "";

            while(i.hasNext()){
                key = i.next().toString();

                if(!key.equals(UserDetails.username)) {
                    al.add(key); /// here want to store only user with doctor role
//currently all users are displaying
                }

                totalUsers++;
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }

        if(totalUsers <=1){
            noUsersText.setVisibility(View.VISIBLE);
            usersList.setVisibility(View.GONE);
        }
        else{
            noUsersText.setVisibility(View.GONE);
            usersList.setVisibility(View.VISIBLE);
            usersList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, al));
        }

        pd.dismiss();
    }
}

我成功获得了根对象“user1”和“user2”，但我也想提取所有其他字段

请告诉我如何更改所有字段的代码。

EDITED

 public void doOnSuccess(String s){
        try {
            JSONObject obj = new JSONObject(s);




            Iterator i = obj.keys();
            String key = "";

            while(i.hasNext()){
                key = i.next().toString();
                JSONObject singleUser = (JSONObject) obj.get(key);
                String role = singleUser.get("role").toString();

                if(!key.equals(UserDetails.username)) {
                    if (role.equals("Doctor")) {
                       // doctors.add(keys);
                        al.add(key);
                    }

                }

                totalUsers++;
            }

        } catch (JSONException e) {
            e.printStackTrace();
        }

        if(totalUsers <=1){
            noUsersText.setVisibility(View.VISIBLE);
            usersList.setVisibility(View.GONE);
        }
        else{
            noUsersText.setVisibility(View.GONE);
            usersList.setVisibility(View.VISIBLE);
            usersList.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, al));
        }

        pd.dismiss();
    }
}

Answer 1

您从用户对象中获取值如下

JSONObject user = obj.getJSONObject("user1");
String role = user.getString("role");
JSONObject presence = user.getJSONObject("presence");
String status = presence.getString("status");

Answer 2

这应该为所有用户提供医生角色。

        JSONParser parser = new JSONParser();

        Object obj = parser.parse(new FileReader(
                "sample.json"));

        JSONObject jsonObject = (JSONObject) obj;

        Set<String> keySet = jsonObject.keySet();
        List<String> doctors = new ArrayList<>();

        for (String keys : keySet) {
            JSONObject singleUser = (JSONObject) jsonObject.get(keys);
            String role = singleUser.get("role").toString();
            if (role.equals("Doctor")) {
                doctors.add(keys);
            }
        }
        System.out.println("Doctor users are --" + doctors);

输出 -

医生用户是--[user2]

Answer 3

您已经嵌入了可以通过 JSON 对象方法轻松访问的 JSON 对象：（假设“userList”是您的根 JSONObject）；

JSONObject user2 = userList.getJSONObject("user2");

然后可以通过以下方式访问这些对象的属性：

String user2Password = user2.getString("password");

请注意，属性“存在”也是一个嵌入的 JSONObject，因此必须使用 JSONObject.getJSONObject() 方法进行访问。

因此，如果要将这些值存储在 ArrayList 中，只需创建：

ArrayList<JSONObject> userArrayList = new ArrayList<JSONObject>();

...然后继续存储值（可能是迭代）：

userArrayList.add(user2);