实例天气预报

步骤：

添加网络权限

<uses-permission android:name="android.permission.INTERNET" />

设置布局视图，activity文件中绑定ID，设置按钮的点击事件，将API网址传值过来，设置输入框输入城市

创建MyTask类继承AsyncTask，设置三个参数在doInbackground方法中，（找水源）创建URL，请求返回，（开水闸）设置openConnection，（建管道）InputStream，判断网页返回码是否为200正确，如果网络正常且返回数据正常，我们才能创建，否则返回“network_failed”（建蓄水池蓄水）InputStreamReader，（水桶盛水）BufferReader设置temp，判断当读取temp是否能读取，当他不为空的时候，提取值，否则直接退出返回stringBuffer.toString（），返回到JSON数据在onPostExcute方法中，判断如果网络返回码错误，提示网络连接失败，否则就正常返回，做JSON解析判断，区分是{}还是【】来定义是object还是array，获得各种风力温度

赋值

视图代码展示：

<EditText android:id="@+id/city_et" android:layout_width="match_parent" android:layout_height="wrap_content" /> <Button android:id="@+id/search_btn" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="查询"/> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="天气："/> <TextView android:id="@+id/wind_tv" android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="温度："/> <TextView android:id="@+id/temp_tv" android:layout_width="match_parent" android:layout_height="wrap_content" /> </LinearLayout> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="风力："/> <TextView android:id="@+id/weather_tv" android:layout_width="match_parent" android:layout_height="wrap_content"/> </LinearLayout>

activity代码演示：

public class Weather2Activity extends AppCompatActivity { private EditText cityET; private TextView weatherTV; private TextView windTV; private TextView tempTV; private Button searchBtn; private String API="https://free-api.heweather.com/s6/weather/now?key=73faf20c8cdc4935943a9703a9068b4f&location="; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_wea); bindID(); searchBtn.setOnClickListener( new View.OnClickListener() { @Override public void onClick(View v) { new MyTask().execute(API+cityET.getText().toString()); } }); } class MyTask extends AsyncTask<String,String,String>{ @Override protected String doInBackground(String... strings) { StringBuffer stringBuffer=new StringBuffer(); try { URL url=new URL(strings[0]);//请求返回 HttpURLConnection connection= (HttpURLConnection) url.openConnection(); InputStream inputStream=null; if (connection.getResponseCode()==200) { inputStream=connection.getInputStream();//还有网络正常且返回数据正常，我们才能创建 }else { return "network_failed"; } InputStreamReader reader=new InputStreamReader(inputStream); BufferedReader bufferedReader=new BufferedReader(reader); String temp=null; while ((temp=bufferedReader.readLine())!=null){ stringBuffer.append(temp); } } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } return stringBuffer.toString(); } @Override protected void onPostExecute(String s) { super.onPostExecute(s); if(s.equals("network_failed")){ Toast.makeText(Weather2Activity.this,"连接失败",Toast.LENGTH_SHORT).show(); }else { //JSON解析 try { JSONObject object=new JSONObject(s); JSONArray array=object.getJSONArray("HeWeather6"); JSONObject object1=array.getJSONObject(0); JSONObject newobject=object1.getJSONObject("now"); String wind=newobject.getString("cond_txt"); String weather=newobject.getString("wind_dir")+newobject.getString("wind_sc")+"级"; String tmp=newobject.getString("tmp"); //赋值 weatherTV.setText(weather); windTV.setText( wind); tempTV.setText(tmp); } catch (JSONException e) { e.printStackTrace(); } } } } private void bindID() { cityET=findViewById(R.id.city_et); windTV=findViewById(R.id.wind_tv); tempTV=findViewById(R.id.temp_tv); weatherTV=findViewById(R.id.weather_tv); searchBtn=findViewById(R.id.search_btn); } }