简易的天气预报APP
项目链接（https://github.com/lubeiling/getWeather-Information-based-Android）
效果图如下，需要输入汉字，AVD可修改输入配置。
1、系统配置：安装好Android Studio，配置好SDK和AVD；
2、开始创建项目
（1）新建Audroid项目
（2）访问互联网， 首先需要设置好相应权限
在app文件夹->mainifests文件夹->AndroidManifest.xml文件中添加：
(3)在MainActivity.java中获取网络数据用到HttpURLConnection的GET方法，并在子线程中访问网络（因为访问网络比较耗时，所以放在子线程中执行；通过消息返回的数据传回页面（更新UI界面）），这里用到的是Handler线程机制：
页面代码（activity_main.xml）如下:
xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> android:id="@+id/cityName" android:layout_width="match_parent" android:layout_height="wrap_content" android:hint="请输入城市名称" /> android:id="@+id/button2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="查询天气" android:onClick="button_click_2" app:layout_constraintTop_toBottomOf="@+id/cityName"/> android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/resultText" app:layout_constraintTop_toBottomOf="@+id/button2" /> MainActivity.java代码如下： package com.example.a2017.homenwork_first; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.support.v7.app.AppCompatActivity; import android.util.Log; import android.view.View; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; import org.json.JSONException; import org.json.JSONObject; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; public class MainActivityextends AppCompatActivity { //更新UI private Handlerhandler =new Handler() { @Override public void handleMessage(Message msg) { // 处理消息时需要知道是成功的消息还是失败的消息 TextView resultText = (TextView) findViewById(R.id.resultText); switch (msg.what){ case 0: resultText.setText(msg.obj.toString()); break; } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } //按钮触发事件 public void button_click_2(View view){ //子线程 Thread t =new Thread(){ @Override public void run() { HttpURLConnection connection =null; try { EditText ed = (EditText)findViewById(R.id.cityName); //在测试时，编辑框中需要填写汉字 String city = java.net.URLEncoder.encode(ed.getText().toString(),"utf-8"); //如果AVD模拟器不能输入汉字时，需要用下面这行代码替换上一行 //String city = java.net.URLEncoder.encode("广州", "utf-8"); URL url =new URL("http://wthrcdn.etouch.cn/weather_mini?city="+city); connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(5000); connection.setReadTimeout(5000); InputStream in = connection.getInputStream(); BufferedReader reader =new BufferedReader(new InputStreamReader(in)); StringBuilder response =new StringBuilder(); String line; while ((line = reader.readLine()) !=null) { response.append(line); } //在日志中输出网络返回的数据 Log.i("TAG", response.toString()); //将获得到的数据进行处理，得到我们需要的格式 String res =new String(response); try { JSONObject jsonObject =new JSONObject(res); JSONObject root = jsonObject.getJSONObject("data"); String log =""; log = log+"城市："+root.getString("city")+"\n"+"PM2.5："+root.getString("aqi")+"\n"+"\n"; JSONObject yes = (JSONObject)root.getJSONObject("yesterday"); log = log + yes.getString("date") +"\t"+yes.getString("high")+"~"+ yes.getString("low")+"\t"+ yes.getString("type")+"\t"+ yes.getString("fx")+"\n"+"\n"+"\n"; for (int i =0;i<4;i++){ JSONObject arr = (JSONObject) root.getJSONArray("forecast").get(i); log = log + arr.getString("date")+"\t"+ arr.getString("high")+"~"+ arr.getString("low")+"\t"+ arr.getString("type")+"\t"+ arr.getString("fengxiang")+"\n"+"\n"+"\n"; } //将消息传回主线程 Message message =new Message(); message.what =0; message.obj = log; handler.sendMessage(message); } catch (JSONException e) { e.printStackTrace(); } }catch (MalformedURLException e) { e.printStackTrace(); }catch (IOException e) { e.printStackTrace(); } } }; t.start();//开始线程 } }