安卓Http请求（三）

1.以天气预报为实例

这次HTTP请求是与json联合使用，这里先介绍一下json，json是一个轻量级数据交换格式。

下面将系统的讲一下json

2.json

json数据又三种，单条、数组、嵌套这三种。其中比较重要的是json数据解析。

其中要利用工具解析json数据比较好用但是json.com

使用json效果如下



单条json数据解析

//json数据
private String jsonStr = "{\"name\":\"张三\",\"age\":21}";
//单条Json解析
JSONObject jsonObject=new JSONObject(jsonStr);
String name=jsonObject.getString("name");
int age=jsonObject.getInt("age");
Log.e("main",name+age);//打印日志

嵌套json数据解析

//json数据
private String jsonStr2 = "{\"name\":\"张三\",\"age\":21,\"info\":{\"class \":\"软件164\",\"id\":1617133101}}";
//嵌套的单条Json解析
JSONObject jsonObject = new JSONObject(jsonStr2);
String name = jsonObject.getString("name");
int age = jsonObject.getInt("age");
JSONObject info = jsonObject.getJSONObject("info");
String classname = info.getString("class");
int id = info.getInt("id");
Log.e("Json", name + age + classname + id);

3.天气预报实例

首先设计ui界面

<?xml version="1.0" encoding="utf-8"?>
<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.ll.skt.WeatherActivity">
<EditText
android:id="@+id/edic"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入城市名"/>
<Button
android:text="查询"
android:id="@+id/btnic"
android:layout_width="match_parent"
android:layout_height="50dp" />
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:textSize="20dp"
android:id="@+id/tianqi"
android:text="天气："
android:layout_width="match_parent"
android:layout_height="50dp" />
<TextView
android:textSize="20dp"
android:id="@+id/wendu"
android:text="温度："
android:layout_width="match_parent"
android:layout_height="50dp" />
<TextView
android:textSize="20dp"
android:id="@+id/fengli"
android:text="风向："
android:layout_width="match_parent"
android:layout_height="50dp" />
</LinearLayout>

</LinearLayout>

然后绑定Id

private void BindId() {
editText = findViewById(R.id.edic);
btn = findViewById(R.id.btnic);
tv1 = findViewById(R.id.tianqi);
tv2 = findViewById(R.id.wendu);
tv3 = findViewById(R.id.fengli);
}

接着获取json数据

private String weatherApI = "https://free-api.heweather.com/s6/weather/now?key=1153ea9909df4ec0b9145e88f9de4632&location=";

创建内部类继承AsyncTask方法

protected String doInBackground(String... strings) {
StringBuffer stringBuffer = new StringBuffer();
try {
URL url = new URL(strings[0]);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
InputStream inputStream = null;
if (httpURLConnection.getResponseCode() == 200) {
//只有网络正常时返回数组正常，才能创建输入流
inputStream = httpURLConnection.getInputStream();                } else {
return "Network_failed";//网络连接失败
}
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

String temp = "";
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();
}

解析json数据

protected void onPostExecute(String s) {
super.onPostExecute(s);
if (s.equals("Network_failed")) {
Toast.makeText(WeatherActivity.this, "网络连接失败", 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 now = object1.getJSONObject("now");
String wether = now.getString("cond_txt");
String wind = now.getString("wind_dir") + now.getString("wind_sc") + "级";
String wendu = now.getString("tmp");
//赋值
tv1.setText(wether);
tv2.setText(wendu);
tv3.setText(wind);

} catch (JSONException e) {
e.printStackTrace();
}
}
}

完成效果如下