如何訪問json中的節點

Question

我想在包含URL的節點中訪問我的json結構如下

{
    "product": {
        "name": "myApp",
        "config": [
            {
                "grade": "first",
                "courses": [
                    {
                        "name": "Math",
                        "url": "example.com"
                    }
                ]
            }
        ]
    }
}

最近，我可以訪問很多節點，例如年級：第一，第二，第三等，並且我使用適配器生成了一個列表視圖，然后例如我首先觸摸了一個項目，然后將其發送到包含課程的另一個活動中，我創建了使用相同的結構訪問課程，但是當我想訪問每個年級的URL時，它會將我發送到最后一個URL，如何訪問特定的URL？ 對不起我的英語不好

Answer 1

使用此代碼發出HTTP請求（用於url中的url傳遞）

HttpParams params = new BasicHttpParams();
HttpConnectionParams.setConnectionTimeout(params, 500);

Client = new DefaultHttpClient(params);
httpget = new HttpGet(url);
ResponseHandler<String> responseHandler = new BasicResponseHandler();
mContent = Client.execute(httpget, responseHandler);

然后使用它來獲取數據：

   JSONObject jsonObject = new JSONObject(mContent);
   String url =json.getJSONObject("product").getJSONObject("config").getJSONObject("courses").getString("url");

---

OUTPUT :: String url包含您要搜索的數據！

---

注意 ::

• 對於url您必須傳遞您嘗試從其獲取JSON響應的URL
• 還要將上述代碼放在Asynchronous task否則由於您正在發出網絡請求而導致崩潰

希望這可以幫助！ 如果有任何錯誤，請還原。

Answer 2

您的json就像這個object-object-array-array-object-string。 因此，您必須像MainActivity一樣解析它，並且在解析之前，您必須從jsonparser.java中的url獲取它。

這是JsonParser.java

package com.skymaster.jsonparser;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JsonParser {

final String TAG = "JsonParser.java";

static InputStream is = null;
static JSONObject jObj = null;
static String json = "";

public JSONObject getJSONFromUrl(String url) {

    // make HTTP request
    try {

        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpPost httpPost = new HttpPost(url);

        HttpResponse httpResponse = httpClient.execute(httpPost);
        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();

    } catch (Exception e) {
        Log.e(TAG, "Error converting result " + e.toString());
    }

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

    // return JSON String
    return jObj;
}
}

這是用於json的MainActivity.java。

package com.skymaster.jsonparser;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;

public class MainActivity extends Activity {

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

    // we will using AsyncTask during parsing 
    new AsyncTaskParseJson().execute();
}

// you can make this class as another java file so it will be separated from your main activity.
public class AsyncTaskParseJson extends AsyncTask<String, String, String> {

    final String TAG = "AsyncTaskParseJson.java";

    // set your json string url here
    String yourJsonStringUrl = "yourjsonurlhere";


    @Override
    protected void onPreExecute() {}

    @Override
    protected String doInBackground(String... arg0) {

        try {

            // instantiate our json parser
            JsonParser jParser = new JsonParser();


            JSONObject json = jParser.getJSONFromUrl(yourJsonStringUrl);


            String url=json.getJSONObject("product").getJSONArray("config").getJSONArray("courses").getJSONObject(0).getString("url");


            }

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

        return null;
    }

    @Override
    protected void onPostExecute(String strFromDoInBg) {}
}
}