基于JAVA的免费天气预报接口查询

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 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 data) {
    StringBuilder sb = new StringBuilder();
    for (Map.Entry 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;
}
}