获取网络数据

主要步骤

1.为更新按钮添加单击事件

在UI线程中，为更新按钮(ImageView)增加单击事件，如下图所示。

2.从SharedPreferences中读取城市的id

通过SharedPreferences读取城市id，如果没有定义则缺省为101010100（北京城市ID）。

3.使用**获取网络数据

4.在AndroidManifest.xml文件中增加访问INTERNET的权限

6.程序运行结果

单击右上角更新按钮。

关键程序代码

package cn.edu.pku.zhangqixun.miniweather;

import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;

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

import cn.edu.pku.zhangqixun.util.NetUtil;

/**
 * Created by zhangqixun on 16/7/4.
 */
public class MainActivity extends Activity implements View.OnClickListener {

    private ImageView mUpdateBtn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.weather_info);

        mUpdateBtn = (ImageView) findViewById(R.id.title_update_btn);
        mUpdateBtn.setOnClickListener(this);

        if (NetUtil.getNetworkState(this) != NetUtil.NETWORN_NONE) {
            Log.d("myWeather", "网络OK");
            Toast.makeText(MainActivity.this,"网络OK！", Toast.LENGTH_LONG).show();
        }else
        {
            Log.d("myWeather", "网络挂了");
            Toast.makeText(MainActivity.this,"网络挂了！", Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onClick(View view) {

        if (view.getId() == R.id.title_update_btn){

            SharedPreferences sharedPreferences = getSharedPreferences("config", MODE_PRIVATE);
            String cityCode = sharedPreferences.getString("main_city_code","101010100");
            Log.d("myWeather",cityCode);


            if (NetUtil.getNetworkState(this) != NetUtil.NETWORN_NONE) {
                Log.d("myWeather", "网络OK");
                queryWeatherCode(cityCode);
            }else
            {
                Log.d("myWeather", "网络挂了");
                Toast.makeText(MainActivity.this,"网络挂了！",Toast.LENGTH_LONG).show();
            }
        }
    }

    /**
     *
     * @param cityCode
     */
    private void queryWeatherCode(String cityCode)  {
        final String address = "http://wthrcdn.etouch.cn/WeatherApi?citykey=" + cityCode;
        Log.d("myWeather", address);
        new Thread(new Runnable() {
            @Override
            public void run() {
                HttpURLConnection con=null;
                try{
                    URL url = new URL(address);
                    con = (HttpURLConnection)url.openConnection();
                    con.setRequestMethod("GET");
                    con.setConnectTimeout(8000);
                    con.setReadTimeout(8000);
                    InputStream in = con.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder response = new StringBuilder();
                    String str;
                    while((str=reader.readLine()) != null){
                        response.append(str);
                        Log.d("myWeather", str);
                    }
                    String responseStr=response.toString();
                    Log.d("myWeather", responseStr);
                }catch (Exception e){
                    e.printStackTrace();
                }finally {
                    if(con != null){
                        con.disconnect();
                    }
                }
            }
        }).start();
    }

}