一、创建一个新的项目

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:orientation="vertical" >

    <Button

        android:id="@+id/reload"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_gravity="center"

        android:text="Reload" />

    <TextView

        android:id="@+id/tvPmData"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:layout_weight="0.40"

        android:text="TextView" />

</LinearLayout>

二、MainActivity.java

package com.xuliugen.airpm;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.UnsupportedEncodingException;

import java.net.MalformedURLException;

import java.net.URL;

import org.json.JSONArray;

import org.json.JSONException;

import org.json.JSONObject;

import android.app.Activity;

import android.os.AsyncTask;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.TextView;

public class MainActivity extends Activity {

    private TextView tvPmData;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        tvPmData = (TextView) this.findViewById(R.id.tvPmData);

        findViewById(R.id.reload).setOnClickListener(new OnClickListener() {

            @Override

            public void onClick(View v) {

                reloadData();

            }

        });

    }

    private void reloadData() {

        tvPmData.setText("Loading...");

        new AsyncTask<Void, Void, String>() {

            @Override

            protected String doInBackground(Void... params) {

                try {

                    BufferedReader reader = new BufferedReader(

                            new InputStreamReader(new URL(

                                    "http://aqicn.org/publishingdata/json")

                                    .openStream(), "utf-8"));

                    String line = null;

                    StringBuffer contentBuffer = new StringBuffer();

                    while ((line = reader.readLine()) != null) {

                        contentBuffer.append(line);

                    }

                    reader.close();

                } catch (UnsupportedEncodingException e) {

                    e.printStackTrace();

                } catch (MalformedURLException e) {

                    e.printStackTrace();

                } catch (IOException e) {

                    e.printStackTrace();

                }

                return null;

            }

            @Override

            protected void onPostExecute(String result) {

                if (result != null) {

                    try {

                        JSONArray jsonArray = new JSONArray(result);

                        JSONObject firstJsonObject = jsonArray.getJSONObject(0);

                        JSONArray pollutantsArray = firstJsonObject.getJSONArray("pollutants");

                        JSONObject firstpollutants = pollutantsArray.getJSONObject(0);

                        tvPmData.setText(String.format("%s %s:%f",

                                firstJsonObject.getString("cityName"),

                                firstJsonObject.getString("localName"),

                                firstpollutants.getDouble("value")));

                    } catch (JSONException e) {

                        e.printStackTrace();

                    }

                }

            };

        }.execute();

    }

}

三、还有一个JSON的案例代码

protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        String jsonStr = "{\"name\":\"jikexueyuan\",\"age\":2,\"arr\":{1,2,3,4,5,6,\"jike\"}}";

        try {

            JSONObject jsonObject = new JSONObject(jsonStr);

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

            System.out.println(name);

            JSONArray array = jsonObject.getJSONArray("arr");

            int firstValue = array.getInt(0);

            System.out.println(firstValue);

        } catch (JSONException e) {

            e.printStackTrace();

        }

    }