Android平台自带了JSON解析的相关API，可以将文件、输入流中的数据转化为JSON对象，然后从对象中获取JSON保存的数据内容。
<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"
tools:context=".MainActivity" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:gravity="center"
android:text="城市："
android:textSize="23sp" />
<EditText
android:id="@+id/city"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="3"
android:inputType="text" />"
</LinearLayout>
<Button
android:id="@+id/query"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="查询"
android:textSize="23sp" />
<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
package com.rainsong.jsondemo;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
EditText et_city;
Button btn_query;
TextView tv_result;
QueryTask task;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_city = (EditText)findViewById(R.id.city);
tv_result = (TextView)findViewById(R.id.result);
btn_query = (Button)findViewById(R.id.query);
btn_query.setOnClickListener(new OnClickListener() {
public void onClick(View view) {
String city = et_city.getText().toString();
if (city.length() < 1) {
Toast.makeText(MainActivity.this, "请输入城市名",
Toast.LENGTH_LONG).show();
return;
}
task = new QueryTask(MainActivity.this, tv_result);
task.execute(city);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
package com.rainsong.jsondemo;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.ArrayList;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.util.EntityUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.TextView;
import android.widget.Toast;
public class QueryTask extends AsyncTask<String, Void, String> {
Context context;
TextView tv_result;
private static final String JUHE_URL_ENVIRONMENT_AIR_PM =
"http://web.juhe.cn:8080/environment/air/pm";
private static final String JUHE_APPKEY = "你申请的APPKEY值";
public QueryTask(Context context, TextView tv_result) {
// TODO Auto-generated constructor stub
super();
this.context = context;
this.tv_result = tv_result;
}
@Override
protected String doInBackground(String... params) {
String city = params[0];
ArrayList<NameValuePair> headerList = new ArrayList<NameValuePair>();
headerList.add(new BasicNameValuePair("Content-Type", "text/html; charset=utf-8"));
String targetUrl = JUHE_URL_ENVIRONMENT_AIR_PM;
ArrayList<NameValuePair> paramList = new ArrayList<NameValuePair>();
paramList.add(new BasicNameValuePair("key", JUHE_APPKEY));
paramList.add(new BasicNameValuePair("dtype", "json"));
paramList.add(new BasicNameValuePair("city", city));
for (int i = 0; i < paramList.size(); i++) {
NameValuePair nowPair = paramList.get(i);
String value = nowPair.getValue();
try {
value = URLEncoder.encode(value, "UTF-8");
} catch (Exception e) {
}
if (i == 0) {
targetUrl += ("?" + nowPair.getName() + "=" + value);
} else {
targetUrl += ("&" + nowPair.getName() + "=" + value);
}
}
HttpGet httpRequest = new HttpGet(targetUrl);
try {
for (int i = 0; i < headerList.size(); i++) {
httpRequest.addHeader(headerList.get(i).getName(),
headerList.get(i).getValue());
}
HttpClient httpClient = new DefaultHttpClient();
HttpResponse httpResponse = httpClient.execute(httpRequest);
if (httpResponse.getStatusLine().getStatusCode() == 200) {
String strResult = EntityUtils.toString(httpResponse.getEntity());
return strResult;
} else {
return null;
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String result) {
if (result != null) {
try {
JSONObject jsonObject = new JSONObject(result);
int resultCode = jsonObject.getInt("resultcode");
if (resultCode == 200) {
JSONArray resultJsonArray = jsonObject.getJSONArray("result");
JSONObject resultJsonObject = resultJsonArray.getJSONObject(0);
String output = context.getString(R.string.city) + ": " + resultJsonObject.getString("city") + "\n"
+ context.getString(R.string.PM25) + ": " + resultJsonObject.getString("PM2.5") + "\n"
+ context.getString(R.string.AQI) + ": " + resultJsonObject.getString("AQI") + "\n"
+ context.getString(R.string.quality) + ": " + resultJsonObject.getString("quality") + "\n"
+ context.getString(R.string.PM10) + ": " + resultJsonObject.getString("PM10") + "\n"
+ context.getString(R.string.CO) + ": " + resultJsonObject.getString("CO") + "\n"
+ context.getString(R.string.NO2) + ": " + resultJsonObject.getString("NO2") + "\n"
+ context.getString(R.string.O3) + ": " + resultJsonObject.getString("O3") + "\n"
+ context.getString(R.string.SO2) + ": " + resultJsonObject.getString("SO2") + "\n"
+ context.getString(R.string.time) + ": " + resultJsonObject.getString("time") + "\n";
tv_result.setText(output);
} else if (resultCode == 202) {
String reason = jsonObject.getString("reason");
tv_result.setText(reason);
} else {
Toast.makeText(context, "查询失败",
Toast.LENGTH_LONG).show();
tv_result.setText("");
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else {
Toast.makeText(context, "查询失败",
Toast.LENGTH_LONG).show();
tv_result.setText("");
}
}
}
字符串资源：string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">JSONDemo</string>
<string name="action_settings">Settings</string>
<string name="hello_world">Hello world!</string>
<string name="city">城市</string>
<string name="PM25">PM2.5指数</string>
<string name="AQI">空气质量指数</string>
<string name="quality">空气质量</string>
<string name="PM10">PM10</string>
<string name="CO">一氧化碳</string>
<string name="NO2">二氧化氮</string>
<string name="O3">臭氧</string>
<string name="SO2">二氧化硫</string>
<string name="time">更新时间</string>
</resources>
Returns the value at index if it exists and is a JSONObject.
原文地址：http://blog.csdn.net/hantangsongming/article/details/42234293
