Android 解析JSON

　　上次讲了XML格式数据的解析方式，这次要说的是如何解析JSON数据格式，相对与XML，JSON解析数据的方式在于它的体积更小，在网络上传输可以更省流量。

　　这次在网上找到一个中国天气json数据的API接口，这就更便于我们直接去解析别人弄好的数据拿来使用，下面这是从网上下载json文件，当然也可以自己简单的编辑：

{"desc":"OK","status":1000,"data":{"wendu":"25","ganmao":"相对于今天将会出现大幅度降温，风力较大，易发生感冒，请注意适当增加衣服。","forecast":[{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 26℃","type":"多云","low":"低温 17℃","date":"2日星期二"},{"fengxiang":"无持续风向","fengli":"5-6级","high":"高温 22℃","type":"大雨","low":"低温 17℃","date":"3日星期三"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 25℃","type":"晴","low":"低温 15℃","date":"4日星期四"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 27℃","type":"晴","low":"低温 16℃","date":"5日星期五"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 23℃","type":"阴","low":"低温 16℃","date":"6日星期六"}],"yesterday":{"fl":"微风","fx":"东风","high":"高温 23℃","type":"中雨","low":"低温 15℃","date":"1日星期一"},"aqi":"79","city":"武汉"}}

　　

 package com.example.weather;

 import java.io.BufferedReader;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.net.URLEncoder;

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

 import android.app.Activity;
 import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.text.TextUtils;
 import android.view.View;
 import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.Toast;

 import com.example.weather.util.ReadStrean;

 public class MainActivity extends Activity {
     protected static final int SUCCESS = 0;
     protected static final int ERROR =1;
     protected static final int FAILL = 2;
     private EditText et_city;
     private TextView tv_one,tv_two,tv_three;
     private String version;
     private Handler handler=new Handler(){
         public void handleMessage(android.os.Message msg) {
             switch (msg.what) {
             case SUCCESS:
                 JSONArray array = (JSONArray)msg.obj;
                 try {
                     tv_one.setText(array.getString(0).toString());
                     tv_two.setText(array.getString(1).toString());
                     tv_three.setText(array.getString(2).toString());
                 } catch (JSONException e) {
                     e.printStackTrace();
                 }
                 break;

             case ERROR:
                 Toast.makeText(MainActivity.this,"请输入正确的城市名称" , 0).show();
                 break;
             case FAILL:
                 Toast.makeText(MainActivity.this,"网络是否连接！" , 0).show();
                 break;
             }
         };
     };

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

 //    private void initDate() {
 //        try {
 //            PackageInfo info = getApplicationContext().getPackageManager().getPackageInfo(getApplicationContext().getPackageName(), 0);
 //            version= info.versionName;
 //
 //            new Thread(){
 //                public void run() {
 //                    try {
 //                        URL url=new URL("http://192.168.1.113:8080/version.json");
 //                        //打开网络连接
 //                        HttpURLConnection conn= (HttpURLConnection) url.openConnection();
 //                        //设置连接方式"GET"
 //                        conn.setRequestMethod("GET");
 //                        //设置http网络连接时间
 //                        conn.setConnectTimeout(5000);
 //                        //请求服务器得到一个返回码
 //                        int code= conn.getResponseCode();
 //                        if(code == 200){
 //                            //getInputStream方法得到输入流其实就是从服务器端发回的数据
 //                            InputStream is=conn.getInputStream();
 //                            StringBuilder builder=new StringBuilder();
 //                            int len;
 //                            String line;
 //                            BufferedReader read=new BufferedReader(new InputStreamReader(is));
 //                            while ((line = read.readLine())!=null) {
 //                                builder.append(line);
 //                            }
 //                            is.close();
 //                            read.close();
 //                            String json = builder.toString();
 //                            System.out.println(json+"123456");
 //                            JSONObject object=new JSONObject(json);
 //                            String appversion = object.getString("version");
 //                            if(version.equals(appversion)){
 //                                runOnUiThread(new  Runnable() {
 //                                    public void run() {
 //                                        Toast.makeText(MainActivity.this, "暂无新版本", 0).show();
 //                                    }
 //                                });
 //                            }else {
 //
 //                            }
 //                        }
 //                        else {
 //                            System.out.println("nononono");
 //                        }
 //                    } catch (Exception e) {
 //                        // TODO Auto-generated catch block
 //                        e.printStackTrace();
 //                    }
 //                };
 //            }.start();
 //        } catch (Exception e) {
 //            // TODO Auto-generated catch block
 //            e.printStackTrace();
 //        }
 //    }

     private void initView() {
         et_city=(EditText) findViewById(R.id.et_city);
         tv_one=(TextView) findViewById(R.id.tv_one);
         tv_two=(TextView) findViewById(R.id.tv_two);
         tv_three=(TextView) findViewById(R.id.tv_three);
     }
     public void onclick (View v){
         final String city = et_city.getText().toString().trim();
         if(TextUtils.isEmpty(city)){
             Toast.makeText(this, "请输入城市名称", 0).show();
             return;
         }
         new Thread(){
             public void run() {
                 try {
                     String path="http://wthrcdn.etouch.cn/weather_mini?city="+URLEncoder.encode(city, "utf-8");
                     URL url = new URL(path);
                     //打开网络连接
                     HttpURLConnection conn = (HttpURLConnection)url.openConnection();
                     //设置连接方式"GET"
                     conn.setRequestMethod("GET");
                     //设置http网络连接时间
                     conn.setConnectTimeout(5000);
                     //请求服务器得到一个返回码
                     int code = conn.getResponseCode();
                     if(code== 200){
                         //getInputStream方法得到输入流其实就是从服务器端发回的数据
                         InputStream is= conn.getInputStream();
                         String json = ReadStrean.readstreanUtil(is);
                         is.close();
                         //创建一个JSONObject对象
                         JSONObject object= new JSONObject(json);
                         //取得json数据格式的第一个键，也是解析json数据的入口
                         String desc = object.getString("desc");
                         if("OK".equals(desc)){
                             //开始解析json
                             JSONObject data = object.getJSONObject("data");
                             JSONArray array= data.getJSONArray("forecast");
                             Message msg=new Message();
                             msg.what=SUCCESS;
                             msg.obj=array;
                             handler.sendMessage(msg);
                         }
                     }else {
                         Message msg=new Message();
                         msg.what=FAILL;
                         handler.sendMessage(msg);
                     }

                 } catch (Exception e) {
                     e.printStackTrace();
                     Message msg=new Message();
                     msg.what=ERROR;
                     handler.sendMessage(msg);
                 }
             };

         }.start();

     }
 }

自定义读取流的工具类：

package com.example.weather.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class ReadStrean {
    public static String readstreanUtil(InputStream is) throws IOException{
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        int len;
        byte [] arr=new byte[1024];
        while((len=is.read(arr))!=-1){
            bos.write(arr, 0, len);
        }
        is.close();
        bos.close();
        return bos.toString("utf-8");

    }
}

xml布局：

 <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="${relativePackage}.${activityClass}" >

     <EditText
         android:id="@+id/et_city"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:hint="请输入城市名称：" />

     <Button
         android:id="@+id/btn_see"
         android:onClick="onclick"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:text="查      看" />

     <TextView
         android:id="@+id/tv_one"
         android:layout_width="match_parent"
         android:layout_height="0dip"
         android:layout_weight="1"
         android:text="今天"
         android:textColor="#FF1493" />

     <TextView
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:background="@android:color/darker_gray" />

     <TextView
         android:id="@+id/tv_two"
         android:layout_width="match_parent"
         android:layout_height="0dip"
         android:layout_weight="1"
         android:text="明天"
         android:textColor="#DC143C" />

     <TextView
         android:layout_width="match_parent"
         android:layout_height="1dp"
         android:background="@android:color/darker_gray" />

     <TextView
         android:id="@+id/tv_three"
         android:layout_width="match_parent"
         android:layout_height="0dip"
         android:layout_weight="1"
         android:text="后天"
         android:textColor="#BC8F8F" />

 </LinearLayout>

最终解析显示图：

添加访问网络权限：<uses-permission android:name="android.permission.INTERNET"/>

源码下载地址：http://pan.baidu.com/s/1qXVGyZU