學習安卓有一段時間了，應該提高自己的實戰能力，做一些簡單的Demo。下面我們介紹一下如何利用網路API實現天氣預報功能，主要涉及到如何利用API獲得網路資料，網路資料返回一般是JSON格式，這裡又涉及到JSON的解析問題，這些都是比較基礎的問題，應該予以掌握。

介面地址：http://apistore.baidu.com/microservice/weather

請求方法：GET

http://apistore.baidu.com/microservice/weather?citypinyin=beijing

{
errNum: 0,
errMsg: "success",
retData: {
   city: "北京", //城市
   pinyin: "beijing", //城市拼音
   citycode: "101010100",  //城市編碼	
   date: "15-02-11", //日期
   time: "11:00", //釋出時間
   postCode: "100000", //郵編
   longitude: 116.391, //經度
   latitude: 39.904, //維度
   altitude: "33", //海拔	
   weather: "晴",  //天氣情況
   temp: "10", //氣溫
   l_tmp: "-4", //最低氣溫
   h_tmp: "10", //最高氣溫
   WD: "無持續風向",	 //風向
   WS: "微風(<10m/h)", //風力
   sunrise: "07:12", //日出時間
   sunset: "17:44" //日落時間
  }    
}

下面搞一下佈局檔案：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:text="天氣預報"
        android:textSize="26dp" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <EditText
            android:id="@+id/myedit"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1111" />

        <Button
            android:id="@+id/searchweather"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="查詢天氣 " />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="城市：" />

        <TextView
            android:id="@+id/city"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="天氣：" />

        <TextView
            android:id="@+id/weather"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="實時氣溫：" />

        <TextView
            android:id="@+id/temp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="最低氣溫：" />

        <TextView
            android:id="@+id/h_temp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:minHeight="30dp"
        android:orientation="horizontal" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="最高氣溫：" />

        <TextView
            android:id="@+id/l_temp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>
 

下面連線工具類：

package org.lxh.demo;

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

public class HttpDownloader {

	private URL url = null;

	/**
	 * 根據URL下載檔案,前提是這個檔案當中的內容是文字,函式的返回值就是文本當中的內容 1.建立一個URL物件
	 * 2.通過URL物件,建立一個HttpURLConnection物件 3.得到InputStream 4.從InputStream當中讀取資料
	 * 
	 * @param urlStr
	 * @return
	 */
	public String download(String urlStr) {
		StringBuffer sb = new StringBuffer();
		String line = null;
		BufferedReader buffer = null;
		try {
			url = new URL(urlStr);
			HttpURLConnection urlConn = (HttpURLConnection) url
					.openConnection();
			urlConn.setRequestMethod("GET");
			urlConn.setConnectTimeout(8000);
			urlConn.setReadTimeout(8000);
			buffer = new BufferedReader(new InputStreamReader(
					urlConn.getInputStream()));
			while ((line = buffer.readLine()) != null) {
				sb.append(line);
			}

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				buffer.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return sb.toString();
	}
}

獲取返回字串之後要對此JSON資料進行解析：

package org.lxh.demo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.json.JSONObject;

public class Util {

	public List<Map<String, Object>> getInformation(String jonString)
			throws Exception {

		JSONObject jsonObject = new JSONObject(jonString);
		JSONObject retData = jsonObject.getJSONObject("retData");
		List<Map<String, Object>> all = new ArrayList<Map<String, Object>>();
		Map<String, Object> map = new HashMap<String, Object>();
		map.put("cityName", retData.optString("city"));
		map.put("weather", retData.optString("weather"));
		map.put("temp", retData.optString("temp"));
		map.put("l_temp", retData.optString("l_tmp"));
		map.put("h_temp", retData.optString("h_tmp"));
		all.add(map);

		return all;

	}

}

下面Activity程式：

package org.lxh.demo;

import java.util.Iterator;
import java.util.List;
import java.util.Map;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class Main extends Activity {
	private EditText citynameEditText;
	private Button searchWeatherButton;
	private TextView citynametTextView;
	private TextView weahterTextView;
	private TextView tempTextView;
	private TextView h_tempTextView;
	private TextView l_tempTextView;
	String jonString;
	ProgressDialog progressDialog;
	private static final int SET = 1;
	@SuppressLint("HandlerLeak")
	private Handler handler = new Handler() {

		@Override
		public void handleMessage(Message msg) {
			switch (msg.what) {
			case SET:
				Util util = new Util();
				try {
					List<Map<String, Object>> all = util
							.getInformation(msg.obj.toString());
					Iterator<Map<String, Object>> iterator = all.iterator();
					while (iterator.hasNext()) {
						Map<String, Object> map = iterator.next();
						Log.d("天氣", map.get("weather").toString());
						citynametTextView.setText(map.get("cityName")
								.toString());
						weahterTextView.setText(map.get("weather").toString());
						tempTextView.setText(map.get("temp").toString());
						h_tempTextView.setText(map.get("l_temp").toString());
						l_tempTextView.setText(map.get("h_temp").toString());

					}
					

				} catch (Exception e) {
					e.printStackTrace();
				} finally {

				}
				break;

			}

		}

	};

	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState); // 生命週期方法
		super.setContentView(R.layout.main); // 設定要使用的佈局管理器
		citynameEditText = (EditText) findViewById(R.id.myedit);
		searchWeatherButton = (Button) findViewById(R.id.searchweather);
		citynametTextView = (TextView) findViewById(R.id.city);
		weahterTextView = (TextView) findViewById(R.id.weather);
		tempTextView = (TextView) findViewById(R.id.temp);
		h_tempTextView = (TextView) findViewById(R.id.h_temp);
		l_tempTextView = (TextView) findViewById(R.id.l_temp);
		
		
		
		searchWeatherButton.setOnClickListener(new OnClickListener() {
			
			public void onClick(View v) {
				new Thread(new NewThread()).start();
				Log.d("按鍵", "Success");
				
				
			}
		});
	}

	private class NewThread implements Runnable {

		public void run() {
			
			String address = "http://apistore.baidu.com/microservice/weather?citypinyin="
					+ citynameEditText.getText().toString();

			HttpDownloader httpDownloader = new HttpDownloader();
			String jonString = httpDownloader.download(address);
			Message msg = Main.this.handler
					.obtainMessage(Main.SET, jonString);
			Main.this.handler.sendMessage(msg);

		}

	}

	

}

執行例項效果：

本例子只解析了幾個資料作為例子，如有需要其他資料，可以自行新增，原理相同。發揮你的想象吧！

最後：

歡迎下載，有問題多交流！