Android 如何访问json中的节点

我想在包含url的节点中访问我的json结构如下

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

---

最近，我可以访问很多节点，例如grade:first、second、third等，我使用适配器生成一个listview，然后我首先触摸一个项目，它会将我发送到另一个包含课程的活动，我创建了在课程中访问的相同结构，但是，当我想访问每个年级的url时，它会将我发送到最后一个url，我如何访问特定的url？对不起，我的英语是

使用此代码进行HTTP请求（对于

url

传入您的url）

---

输出：

字符串url

包含您正在搜索的数据

---

注意：

• 对于

  url

  ，您必须传递您试图从中删除的url 获取JSON响应
• 同时将上述代码放在

  异步任务中

  否则 崩溃，因为您正在发出网络请求

---

希望这有帮助！如果有任何错误，请还原。

您的json类似于此对象字符串。 所以你必须像MainActivity一样解析它 在解析之前，您必须从jsonparser.java中的url获取它

这是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;
}
}

这是您的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) {}
}
}

package com.skymaster.jsonparser；
导入org.json.JSONArray；
导入org.json.JSONException；
导入org.json.JSONObject；
导入android.os.AsyncTask；
导入android.os.Bundle；
导入android.app.Activity；
导入android.util.Log；
公共类MainActivity扩展了活动{
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
//我们将在解析期间使用AsyncTask
新建AsyncTaskParseJson（）.execute（）；
}
//您可以将这个类作为另一个java文件，这样它将与您的主要活动分离。
公共类AsyncTaskParseJson扩展AsyncTask{
final String TAG=“AsyncTaskParseJson.java”；
//在此处设置json字符串url
字符串yourJSonString=“yourjsonurlhere”；
@凌驾
受保护的void onPreExecute（）{}
@凌驾
受保护的字符串doInBackground（字符串…arg0）{
试一试{
//实例化我们的json解析器
JsonParser jParser=新的JsonParser（）；
JSONObject json=jParser.getJSONFromUrl（yourJsonStringUrl）；
字符串url=json.getJSONObject（“产品”）.getJSONArray（“配置”）.getJSONArray（“课程”）.getJSONObject（0.getString（“url”）；
}
}捕获（JSONException e）{
e、 printStackTrace（）；
}
返回null；
}
@凌驾
受保护的void onPostExecute（字符串strFromDoInBg）{}
}
}

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;
}
}

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) {}
}
}