Http请求和Json解析结合实例 （简易的天气预报系统）

1、效果展现

2、首先创建一个activity，修改里面的布局文件，添加控件，设置id

<LinearLayout 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:orientation="vertical"
    android:layout_height="match_parent"
    tools:context="com.example.myapplication2.WeatherTestActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="50dp">

        <Button
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:text="请输入城市名:"/>

        <EditText
            android:id="@+id/weather_test_et"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </LinearLayout>
    <Button
        android:id="@+id/weather_test_btn"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="查询"
        android:gravity="center"/>

    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="50dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:textSize="30sp"
            android:text="天气:"/>

        <TextView
            android:layout_marginLeft="10dp"
            android:id="@+id/weather_test_weather"
            android:layout_width="wrap_content"
            android:gravity="center"
            android:textSize="30sp"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="50dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:textSize="30sp"
            android:text="温度:"/>

        <TextView
            android:layout_marginLeft="10dp"
            android:id="@+id/weather_test_temp"
            android:layout_width="wrap_content"
            android:gravity="center"
            android:textSize="30sp"
            android:layout_height="wrap_content" />


    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:orientation="horizontal"
        android:layout_height="50dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:gravity="center"
            android:textSize="30sp"
            android:text="风力:"/>

        <TextView
            android:layout_marginLeft="10dp"
            android:id="@+id/weather_test_windpower"
            android:layout_width="wrap_content"
            android:gravity="center"
            android:textSize="30sp"
            android:layout_height="wrap_content" />


    </LinearLayout>

</LinearLayout>

3、在activity中进行绑定控件，设置监听，调用自定义类，启动线程

public class WeatherTestActivity extends AppCompatActivity {

    private Button searchBtn;
    private EditText editText;
    private TextView weatherTv;
    private  TextView tempTv;
    private  TextView windTv;
    //在这里使用的是和风天气的api，登录和风天气的官网，获得普通用户挨批，添加key，地址则由输入的地址决定
    private String weatherAPI = "https://free-api.heweather.com/s6/weather/now?key=14134781d3024bf3945b32caeebf29ae&location=";

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

        bangID();
        searchBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //读取输入的地址，获得完整的天气预报api，传给子线程读取输入流
                String api_str = weatherAPI+editText.getText().toString();
                //在自定义类中添加构造方法，传值，启动线程时传入api
                new WeatherTest(WeatherTestActivity.this,editText,weatherTv,tempTv,windTv).execute(api_str);
            }
        });
    }

    private void bangID() {
        searchBtn = findViewById(R.id.weather_test_btn);
        editText = findViewById(R.id.weather_test_et);
        weatherTv = findViewById(R.id.weather_test_weather);
        tempTv = findViewById(R.id.weather_test_temp);
        windTv = findViewById(R.id.weather_test_windpower);
    }
}

4、在自定义类中完成Http请求和Json数据的解析（获得的json数据放到www.json.cn中，这样结构就清晰明了了），这样项目就完成了，运行一下吧。

//在自定义类中完成Http请求和Json数据的解析
public class WeatherTest extends AsyncTask<String,Integer,String> {

    private EditText editText;
    private TextView weatherTv;
    private  TextView tempTv;
    private  TextView windTv;
    private Context context;
    //通过构造方法传值
    public WeatherTest (Context context,EditText editText,TextView weatherTv,TextView tempTv,TextView windTv){
        this.context = context;
        this.editText = editText;
        this.weatherTv = weatherTv;
        this.tempTv = tempTv;
        this.windTv = windTv;

    }





    @Override
    protected String doInBackground(String... strings) {
        InputStream inputStream = null;
        StringBuffer stringBuffer = null;

        try {
            //创建URL对象，接收api
            URL url = new URL(strings[0]);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            //判断是否联网
            if(httpURLConnection.getResponseCode()==200){
                inputStream = httpURLConnection.getInputStream();
            }
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            stringBuffer = new StringBuffer();
            String temp = null;
            while((temp=bufferedReader.readLine())!=null){
                stringBuffer.append(temp);
            }
            bufferedReader.close();
            inputStreamReader.close();
            inputStream.close();

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


        return stringBuffer.toString();
    }

    @Override
    protected void onPostExecute(String s) {
        super.onPostExecute(s);
        try {
            //创建jsonobject对象，接收字符串
            JSONObject jsonObject  = new JSONObject(s);
            //创建jsonarray对象，接收数组
            JSONArray jsonArray = jsonObject.getJSONArray("HeWeather6");
            //创建jsonobject对象，接收数组的第一个对象
            JSONObject jsonObjectindex = jsonArray.getJSONObject(0);
            //创建jsonobject对象，接收对象
            JSONObject jsonObjectnow = jsonObjectindex.getJSONObject("now");
            //读取数据
            String cond_txt = jsonObjectnow.getString("cond_txt");
            String tmp = jsonObjectnow.getString("tmp");
            String wind_dir = jsonObjectnow.getString("wind_dir");
            String wind_sc  = jsonObjectnow.getString("wind_sc");
            //设置值
            weatherTv.setText(cond_txt);
            tempTv.setText(tmp+"℃");
            windTv.setText(wind_dir+wind_sc+"级");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}