网络载入数据和解析JSON格式数据案例之空气质量监測应用

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();
}
}