1、开通接口
天气预报接口服务使用的聚合数据提供的免费接口，每天可以100次免费调用。可以通过https://www.juhe.cn/docs/api/id/73注册及开通。
2、通过Java发起城市天气查询
package cn.juhe;
import net.sf.json.JSONObject;
import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;
public class SimpleWeather {
// 天气情况查询接口地址
public static String API_URL = "http://apis.juhe.cn/simpleWeather/query";
// 接口请求Key
public static String API_KEY = "xxxxxxxxxxxxxx";
public static void main(String[] args) {
String cityName = "北京";
queryWeather(cityName);
}
/**
* 根据城市名查询天气情况
*
* @param cityName
*/
public static void queryWeather(String cityName) {
Map<String, Object> params = new HashMap<>();//组合参数
params.put("city", cityName);
params.put("key", API_KEY);
String queryParams = urlencode(params);
String response = doGet(API_URL, queryParams);
try {
JSONObject jsonObject = JSONObject.fromObject(response);
int error_code = jsonObject.getInt("error_code");
if (error_code == 0) {
System.out.println("调用接口成功");
JSONObject result = jsonObject.getJSONObject("result");
JSONObject realtime = result.getJSONObject("realtime");
System.out.printf("城市：%s%n", result.getString("city"));
System.out.printf("天气：%s%n", realtime.getString("info"));
System.out.printf("温度：%s%n", realtime.getString("temperature"));
System.out.printf("湿度：%s%n", realtime.getString("humidity"));
System.out.printf("风向：%s%n", realtime.getString("direct"));
System.out.printf("风力：%s%n", realtime.getString("power"));
System.out.printf("空气质量：%s%n", realtime.getString("aqi"));
} else {
System.out.println("调用接口失败：" + jsonObject.getString("reason"));
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* get方式的http请求
*
* @param httpUrl 请求地址
* @return 返回结果
*/
public static String doGet(String httpUrl, String queryParams) {
HttpURLConnection connection = null;
InputStream inputStream = null;
BufferedReader bufferedReader = null;
String result = null;// 返回结果字符串
try {
// 创建远程url连接对象
URL url = new URL(new StringBuffer(httpUrl).append("?").append(queryParams).toString());
// 通过远程url连接对象打开一个连接，强转成httpURLConnection类
connection = (HttpURLConnection) url.openConnection();
// 设置连接方式：get
connection.setRequestMethod("GET");
// 设置连接主机服务器的超时时间：15000毫秒
connection.setConnectTimeout(5000);
// 设置读取远程返回的数据时间：60000毫秒
connection.setReadTimeout(6000);
// 发送请求
connection.connect();
// 通过connection连接，获取输入流
if (connection.getResponseCode() == 200) {
inputStream = connection.getInputStream();
// 封装输入流，并指定字符集
bufferedReader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
// 存放数据
StringBuilder sbf = new StringBuilder();
String temp;
while ((temp = bufferedReader.readLine()) != null) {
sbf.append(temp);
sbf.append(System.getProperty("line.separator"));
}
result = sbf.toString();
}
} catch (IOException e) {
e.printStackTrace();
} finally {
// 关闭资源
if (null != bufferedReader) {
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != inputStream) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection != null) {
connection.disconnect();// 关闭远程连接
}
}
return result;
}
/**
* 将map型转为请求参数型
*
* @param data
* @return
*/
public static String urlencode(Map<String, ?> data) {
StringBuilder sb = new StringBuilder();
for (Map.Entry<String, ?> i : data.entrySet()) {
try {
sb.append(i.getKey()).append("=").append(URLEncoder.encode(i.getValue() + "", "UTF-8")).append("&");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
String result = sb.toString();
result = result.substring(0, result.lastIndexOf("&"));
return result;
}
}
