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：
<uses-permission android:name="android.permission.INTERNET" />
(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:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstrainLayout xmlns:android="http://schemas.android.com/apk/res/android"
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">
<EditText
android:id="@+id/cityName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入城市名称" />
<Button
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"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/resultText"
app:layout_constraintTop_toBottomOf="@+id/button2" />
</android.support.constraint.ConstrainLayout>
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
}
}
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